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Home , Adobe, Government Palace (Peru), Mudbrick, Rural housing

egional Project on Cultiiral Heritage d Development UNDP/UNESCO INTERN AjouNAL:- .711‘te(),SILMsttaAND l. Ok‘,%, lira TRAINING- wcowsa ON THE COI L V4 N OF ternational Centre for the Study the Preservation and the Final Report and Major Papers storation of Cultural Property - ICCROM - Cusco (Paul x

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BIBLIOTHEQUE

5 0 33 o c Y1K G "Y-1.&.<1 © Regional Project on Cultural Heritage and Development UNDP/UNESCO P.O. Box 4480 Lima 100,

ICCROM 13 Via di S. Michele 00153 Rome, Italy adobe INTERNATIONAL SYMPOSIUM AND TRAINING WORKSHOP ON THE CONSERVATION OF ADOBE

Final Report and Major Papers

Lima - Cusco (Peru) 10-22/September 1983

Organized by: UNDP/UNESCO REGIONAL PROJECT ON CULTURAL HERITAGE AND DEVELOPMENT

PHU

INTERNATIONAL CENTRE FOR THE STUDY OF THE PRESERVATION AND THE RESTORATION OF CULTURAL PROPERTY (ICCROM), ROME ICCROM

In collaboration with: National Institute of Culture (Peru) UNESCO Convention for the Protection of the World Cultural and Natural Heritage National Project on Cultural Heritage Peru UNDP/UNESCO Ford Foundation International Council on Monuments and Sites (ICOMOS) lo-Latin American Institute (IILA)

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Index

Presentation Characterization of Adobe as . Cevat Erder Preservation Techniques 7 Sylvio Mutal 9 Giacomo Chiari • 31

Introduction 13 Notes on the Manufacture of Adobe Blocks for Introduction to the Historic Use of Earthen the Restoration of Earthen Building Materials. Case Study: Alejandro Alva Balderrama Andre Stevens • 19 Jeanne Marie Teutonico • 41

Conservation and Use of Historic Centres and Monuments Adobe Buildings. Some Restoration Examples Franca Helg 27 Sergio Rojo • 55

5 Assessment of Structural Faults and Monitoring Raw Earth Techniques CBancol Used in of Structural Movements in Adobe Nianti Bouare 117 Buildings and Ruins Todd Rutenbeck , 61 The Protection and Conservation of the of Tlaxcala, Mexico A Conservation Survey of Adobe Buildings Gilberto Reyes Zepeda 121 Anthony Crosby • 65 Tumacacori National Monument Earthquakes and Adobe Structures Paul Mc Henry, Jr. .40 123 Julio Vargas Neumann 69 Adapting Adobe Buildings and Monuments to New Use • Investigation of the Long-Term Efectiveness of an Ethyl Silicate-Based Consolidant Roberto Samanez Argumedo 127 on Seymour Z. Lewin Protection and Conservation of Adobe Historic Complexes Paul M. Schwartzbaum • 77 Jacques Verite 133 Conservation of Structures and Adobe Decorative Conclusions and Recommendations Elements in Chan-Chan 139 Ricardo Morales Gamarra • 83 Lecturers 143

A Survey of the Painted `Viharas' Participants 144 of Sri Lanka Ashley de Vos 91 Observers 146

6 Presentation

Concern at international level for the conserva- of the University of Turin, and at the Iraqi- tion of adobe has a brief history. It is only a little more Italian Institute in Baghdad. This research resulted in than a decade ago that action in this area was initiated the formulation of a series of questionnaires aimed at and for this we are greatly indebted to Professor Piero pinpointing the basic problems and defining the general Gazzola. characteristics in the various regions, as as stimu- Professor Gazzola, who was President of ICOMOS lating a deeper concern for the study of the protection and a member of the Council of ICCROM as well as a of adobe structures. teacher on ICCROM's Architectural Conservation cours- In the wake of these researches two Interna- es, arrived at the conclusion, after travelling extensive- tional Symposia on this subject were organized and held ly and observing the situation at first hand around in (1971 and 1976) by the Iranian National Com- the world, that cooperation at the international level mittee of 1COMOS. was the best way to combat effectively the deterio- Since the second symposium aimed to produce a ration of adobe structures. He put the initial accent document that would serve to establish a methodology —and rightly so— on research and field projects. The for the study of adobe structures and archaeological first of these began in 1968, with ICCROM's participation ruins, another questionnaire was drawn up by ICCROM in the research being carried out then in with the and presented as a major issue at the Regional Meeting cooperation of the Institut Royal du Patrimoine Ar- on Conservation held at Santa Fe, , in 1977. tistique in Brussels, the Institute of Mineralogy and As a result of this meeting, this questionnaire became

7 a fairly detailed model for the full investigation of the communication— of UNDP/UNESCO, and the ICOMOS use of adobe as a building material. The ultimate aim International Committee on Adobe, with the support of was to stimulate experimentation and to standardize the World Cultural Heritage Convention of UNESCO, methods, and it was felt that this task of standardi- and under the auspices of the National Institute of zation ought to be entrusted to international organi- Culture of Peru, organized the International Symposium zations and committees. and Training Workshop on the Conservation of Adobe in The third symposium, organized in Ankara in Lima and Cusco. 1980, provided an opportunity to revise the more im- Thus this neeting, which was a follow-up at na- portant tests carried out after the second Yazd meeting. tional level of the previous international symposia on Althcugh some positive results had been obtained, the adobe conservation, had the ambitious aim of expanding majority of the real problems remained unsolved, es- current knowledge of the appropriate methods and pecially with regard to the long-term reliability of the techniques for adobe conservation among those techni- testing methods. While scientists favoured further testing cians responsible for the conservation of the cultural and research, conservators objected to expensive long- heritage. range experiment in view of the rapid deterioration It should be stressed once more that any de- rate of the material. velopment in this field requires both financial invest- Evidently, it is not possible to arrive at definitive ment and long-term sponsoring. These can and should solution on the basis of a few international meetings. be provided by national agencies, with international Such meetings can serve only to indicate a possible organizations acting merely as promoters. Continuity can orientation for research activities and to suggest pos- be secured through national efforts and agencies alone. sible areas of study and field work. In fact, following The way in which this Symposium was organized, the second Yazd meeting two pilot projects were and the Peruvian contribution to it, are a perfect initiated: one at Tumacacori, U.S.A., and the other in example of this. This lightens our pessimism somewhat Peru at Chan Chan. and we believe that it could herald a turning-point in In 1983, sufficient time had elapsed since the the field. symposia held in Yazd and Ankara to justify the organi- We trust that this publication, which includes zation of another international meeting. It was felt, the major papers presented at the symposium, will be however, that at this meeting special emphasis should of aid to those restorers and conservators engaged in be placed upon training. This led us therefore to select the preservation of adobe monuments, sites, and historic for this meeting experts who were also trainers and centres throughout the world. participants who could be readily integrated into the workshop. It is with these criteria in mind that ICCROM, Prof. Dr. Cevat Erder in collaboration with the Regional Project on Cultural Heritage — the cultural dimension of development and Director of ICCROM

8 Adobe monuments and the for build- The Symposium-Training Workshop on the Con- ing with earth are part of the heritage of many nations. servation of Adobe held in Cusco in 1983 brought Earth, which has been used as a building material for together experts from Latin America and the Caribbean, over 10,000 years, has given rise to a great variety the United States, , Asia and the Middle East and wealth of architectural forms throughout the world. thanks to the collaboration of the National Institute This monumental heritage is seriously endan- of Culture of Peru, of ICCROM, of UNDP, the World gered today, both by and industrialization Heritage Convention of UNESCO, ICOMOS and various processes, as well as by natural and causes of public and private foundations, such as the Ford Foun- decay. dation and I ILA But the cultural heritage of a people comprises This colloquium centred on the different preser- more than its monuments and historic centres. The task vation techniques applicable to adobe monuments, taking of conservators and restorers therefore, should be not into account natural causes of deterioration due to only to safeguard of monuments and other adobe the passage of time, as well as the damage caused by edifices but to rescue as well the traditional methods earthquakes and other natural disasters. After studying and endogenous still in use in those coun- the characteristics of adobe as a building material and tries where earth is used as a building material — and analyzing its physical, chemical and mechanical proper- which are in danger of disappearing. ties, the structural conservation of adobe buildings was

9 discussed. Various techniques for the assessment of the year 2000, it will be necessary to build 500 million structural faults, the consolidation of foundations and homes to the inhabitants of developing countries. strengthening of walls were explained, as well as the This deficit continues to grow; in most Third World preventive measures which should be taken in view of countries, at least 25% of the population (and some- earthquakes. times 50%) lives in slums, shantytowns or improvised The treatment of painted and decorated surfaces shelters. over adobe structures was analyzed in depth, given the The solution in many parts of the world will be number of adobe monuments that possess valuable mural to turn to adobe. For a building material to be used paintings. for the habitat of the poor, it must be used by the The adaptation of adobe buildings to new use poor themselves. It must be cheap, easy to use and was also discussed. Different typologies of earthen immediately available. buildings were studied, and existing attitudes toward Adobe has all these characteristics. One hears a adobe conservation were analyzed. lot about "" today: it is time Finally, the protection and conservation of his- that city planners and builders stop praising traditional toric and urban complexes built with adobe was construction materials and start using them. It is ne- discussed. cessary, therefore, to change existing attitudes toward These topics were analyzed by architects, art adobe housing. historians, chemists, structural engineers and urban Some Third World leaders, such as Nyerere and planners who had been brought together by the Sym- Indira Ghandi, have spoken about these problems. Says posium. Nyerere: "People insist on waiting to obtain a tin roof The special characteristics of adobe, and notably over 'European earth' — that is, cement. If we are to its fragility were taken into account, as well as the progress... we must overcome these mental blocks... specific techniques required for its conservation, which The majority of the people do not have means to buy a differ from those applicable to the conservation of cement house. Therefore, if we do not help them build other materials, such as stone or wood. a house made of improved traditional materials... we This Symposium-Training Workshop is compara- will have done nothing to help them live in a decent ble to the Wood Conservation Course organized in home". Norway, or that of Conservation of Stone, which takes Indira Ghandi, during a personal interview with place in Venice. Many of the Third World countries also Earthscan in 1980 stated: "all the new are built face problems concerning the preservation of wood to consume energy. They are hot in summer and cold (especially in tropical regions) as well as stone. It is in winter. But not our old houses... We should hoped that, in the future, these courses will be pro- take another look at the old technology. There is much jected to developing countries. logic in what people have been doing throughout the It should be stressed that the two previous years, in accordance with their climate, their environ- meetings on the conservation of adobe (the Seminars ment, their lifestyle. We cannot conserve all of it, at Yadz and Ankara) took place in Third World coun- because our way of life has changed, but I do believe tries. This Symposium was, thus, the third to be organ- we can conserve a great deal, adapting it and making ized in a developing country. it more efficient". The conservation of adobe should be placed We should like to recall here Hassan Fathy, the within the global context of development. For this Egyptian architect who revalued adobe architecture in reason, parallel lectures were organized during the Egypt and built a whole town in adobe near Luxor, in Symposium and open to the public, dealing with the use spite of mockery and opposition. In 1980, Fathy ob- of adobe in contemporary housing. tained the Aga Khan prize for and One of the main problems in the world today is today his work is seen as a significant contribution to the housing shortage. We know that, between now and contemporary architecture. Fathy's experiments should

10 be food for thought in our architecture schools. wareness of the need to preserve and revalue both One hears much today about "horizontal cooper- the old monuments and sites in raw earth and the ation" as well. It is true that there is no easy way to appropriate techniques for building with this material. break the existing technological dependence vis a vis On the eve of the next meeting on this subject, the industrialized nations, yet we believe that the de- which will take place in Senegal in 1986, we hope it veloping world can and should benefit from technologies will be of help to those who work in this area of to be found in countries which face similar problems. conservation. A greater exchange of information is necessary, and many projects could be faced jointly. In the field of adobe, this "south-south" cooperation is extremely per- tinent: this became evident in the Lima Symposium- Training Workshop. Events such as this one help fur- Sylvio Mutal ther technological exchange and lead to share conser- vation experiments which can be applied in other parts Chief Technical Advisor of the world where problems are similar. and Regional Coordinator The aim of this publication is to disseminate Regional Project on Cultural knowledge concerning adobe, and to create an a- Heritage and Development UNDP/UNESCO

4 6 Introduction

International Symposium and Training Workshop on the Conservation of Adobe Lima - Cusco, 10-22 September 1983

Background Regional Project on Cultural Heritage and Development in the city of Cusco on the Conservation and Restora- The International Centre for the Study of the tion of Archaeological and Architectural Monuments, Preservation and the Restoration of Cultural Property as well as of Historical Centres and Sites. (ICCROM), in close collaboration with the Internation- al Council of Monuments and Sites (ICOMOS) and The Symposium-Workshop brought together over UNESCO has organized, in past years, a number of 80 lecturers and participants from Latin America and the international Symposia related to the conservation of Caribbean, Africa, the Middle East, Asia, Europe and adobe. the United States. This event received the support of Following the seminars held in and Turkey, the UNESCO Convention for the Protection of the an International Symposium took place in Lima and Cus- World Cultural and Natural Heritage and the United co, Peru, from 10 to 22 September 1983. This event Nations Development Programme, and that of govern- was of an innovative nature, inasmuch as it consisted mental and non-governmental specialized agencies in- at the same time of a training Workshop. terested in the field of cultural heritage. The Symposium The Symposium-Workshop was part of a series was organized jointly by ICCROM and the UNDP/ of courses organized since 1975 by the UNDP/UNESCO UNESCO Regional Project on Cultural Heritage and

13 Development under the auspices of the National Insti- duction to the historic use of earthen building materials". tute of Culture of Peru. "Use and techniques of earthen building materials in The main objectives of this meeting were: a world context". "Inventory and survey of adobe buildings". —To provide a meaningful follow-up to previous sym- "The posia on the conservation of adobe, in keeping with characterization of adobe as an earthen building the established functions of ICCROM. material; physical and chemical properties; mechanical properties, methods for the characterization and pre- —To strengthen ICCROM's active collaboration in de- centralized and joint programmes with the Regional servation of adobe as a building material". Project on Cultural Heritage and Development in Latin "Structural conservation of earthen architecture, con- solidation of foundations, monitoring structural move- America and the Caribbean, thus attending to the need of constant support in the training of local personnel ments, repair of earthen walls, reinforcement of adobe dedicated to the conservation of adobe. masonry, assessment of earthquake damage, prevention —To encourage a greater exchange of information on and repair". the techniques of adobe conservation, as known in "Painted and decorated surfaces on adobe structures: different parts of the world where this material is still characterization, damage and treatment". part of a traditional, endogenous technology, used both "Adapting adobe buildings and monuments to new use". in present-day construction and in the conservation of "The protection and conservation of earthen historic monuments and historical sites. This exchange, it was towns and/or urban settlements". deemed, would help to strengthen horizontal cooper- The topics discussed centred on the history of ation between developing nations (TCDC) . adobe and its use from antiquity to the present, as well The dissemination of appropriate methods and as with the problems of its conservation. It was stated techniques for the preservation of earthen building that earth, which constitutes 74% of the world's crust materials and mud structures was the main priority of has been used as a building material since over 10,000 the Symposium, which provided a forum where interna- years ago. A. Stevens, from Belgium, lectured on the tional specialists from related disciplines presented and extremely varied edifices which have been built with exchanged ideas and information. this material throughout history. Archaeological and historical remains in the Near East, Egypt, Iran, Central Asia and North and South America were analyzed. Fran- Development of the Symposium ca Helg (Italy-IILA) and C. Erder (ICCROM) also in- The meeting was inaugurated by the former Min- tervened in these discussions. ister of Education of Peru, Mr. Patricio Ricketts who The use and techniques of building with earth addressed the participants and stressed the importance were also analyzed in the Latin American context. Differ- of this event. Other speakers at the inaugural session ent regional techniques, such as compacted earth, com- included Dr. Cevat Erder, President of ICCROM; Mr. pressed earth (tapia, tapial) and or bahareque Sylvio Mutal, Chief Technical Advisor and Regional Co- ( and daub) were examined. ordinator of the UNDP/UNESCO Regional Project on It was emphasized that before any intervention Cultural Heritage; Mr. Eric Perrin, Resident Representa- in a building, these techniques should be studied and tive, a.i., United Nations Development Programme the main causes of deterioration should be assessed. (UNDP) and a representative of the National Insti- Restorers should be knowledgeable of the different tute of Culture of Peru. restoration procedures, which must be applied in a The Symposium-Workshop discussed extensively, in correct sequence. Lecturers Samanez (Peru) and Reyes conference-courses and working papers, the following (Mexico) provided specific examples of restoration topics: carried out in Cusco, Peru and Tlaxcala, Mexico. Mr. —"Concepts and attitudes in conservation: an intro- Reyes showed a booklet published in Mexico as part of

14 a government training programme for self-help in history and description of the mural paintings over building. adobe walls found in the cloister of San Francisco in A. Crosby (USA) spoke of the importance of sur- Lima. veying an adobe building or structure to determine the P. Schwartzbaum (ICCROM) and S. Lewin (USA) causes of decay. Signs of deterioration such as basal explained the use of an ethyl-silicate based solution erosion, surface erosion, cracks, bulges, creep or upper as part of the treatment for conservation of a mural wall displacement should be examined. Problems of painting of the Age found in Jordania in deterioration he explained, might be caused by running 1979, and discussed the long-term effects of this con- , strong wind, high water-table, excessive humidity solidant on adobe. or external loading. The different available to R. Samanez (Peru) and F. Helg (Italy-IILA) dealt detect these problems were examined. Simple ones, with the adequate adaptation of old buildings to new including plumb-bobs, levels and probes, as well as more use. They insisted that the same materials as those sophisticated ones, including laser and microwave tech- used originally should be utilized in restoration, while nology, were discussed. The importance of under- not disregarding structural reinforcement. Both experts standing and having respect for the material were saw the need to renovate old buildings in historical stressed. centres, adapting them to new use, in keeping with the When dealing with the characteristics of earth needs of the community. as a building material, G. Chiari (ICCROM) and Sergio J. Write (France-UNESCO) analyzed "verna- Rojo () discussed its main properties. analysis cular architecture" as opposed to "culture architecture". and different lab and in situ tests were explained. He underlined the problems faced in conservation and Recommendations for stabilization and improvement warned against "nostalgia". were discussed, as well as the different existing tech- N. Bouare, from Mali, and Ashley de Vos, from niques for making the adobe blocks. This last aspect Sri Lanka gave examples of in was treated in depth by A. Alva (ICCROM), who pre- both countries. Bouare explained different African tech- sented a paper on the fabrication and preservation of niques for building with earth while De Vos related his . experiments in the consolidation of painted surfaces over earthen walls in Buddhist shrines in Sri Lanka. J. Vargas (Peru) analyzed seismic behaviour in The present publication includes an abridged adobe structures. He stressed the need to develop version of the main papers presented during the Sym- prevention programmes, rather than having to perform posium.' restoration interventions. Aside from the regular sessions of the Symposium, T. Rutenbeck (USA), lecturing on structural mon- a series of lectures on the use of adobe in contem- itoring, explained how to predict the danger of struc- tural collapse. He discussed the precise levelling equipment (such as electronic gages) used to measure deflection, differential settlement, geological movements 1. Because of lack of space, the following papers are not and progressive wall tilts. included in this publication: Ricardo Estabridis, "Mural Paintings S. Rojo (Chile) gave examples of different in the Main Cloister of San Francisco el Grande, Lima"; Sergio Ro- structural systems used in adobe construction, and jo, "Physical Characteristics of Adobe"; Ricardo Morales, "Moche Murals: Technique and Conservation"; Roberto Samanez Argume- showed structural restoration work carried out in do, "Use and Techniques of Earthen Building Materials in the historic monuments in Chile. Latin American Context"; Ignacio Garate, "Address to the Sym- The conservation of high-relief friezes and paint- posium on Adobe". We have, on the other hand, included two ed surfaces in Chan Chan and other sites of the Moche papers in their entirety; those presented by Giacomo Chiari and culture in northern Peru was the topic addressed by Alejandro Alva, both from ICCROM, for we believe their content to be useful for those restorers dedicated to the conservation R. Morales (Peru) , while R. Estabridis (Peru) gave a of adobe.

15 porary housing were open to the public during the Follow up activities 1984/85 evenings. Both rural and urban experiences in differ- ent parts of the world were discussed, as well as the attitudes of the population towards adobe housing. Pilot projects The Symposium-Workshop reiterated the technical conclusions of the meetings held during the previous The Symposium emphasized the need to establish decade on the preservation and treatment of adobe. a pilot project to study the specific problems of painted Special emphasis was placed on protective measures to surfaces on mud walls in order to improve preservation be taken during and after archaeological excavations: Techniques. Peru, a country with a rich cultural he- the new treatments developed for conservation and ritage in this field, was chosen as the site of this maintenance; the appropriate techniques to be used in project, which will also include the training of competent sites made of partially baked mud and the adequate personnel in this area. methods of conservation and protection of historical Other pilot projects under consideration include centres and monuments. the conservation of mudbrick buildings in seismic areas. as well as in regions affected by environmental pol- Two photographic exhibits were displayed in gal- lution and climatic erosion. leries adjoining the main meeting hall. "Adobe in Ame- Bearing in mind the recommendations of the rica: its History, Conservation and Contemporary Use" Symposium, early in 1984 the UNDP/UNESCO Regional (mounted by Mario and Maria Acha from the UNDP/ Project on Cultural Heritage began to contact special- UNESCO Regional Project on Cultural Heritage with ized institutions and funding sources in order to de- the support of the Ford Foundation) gave examples velop these projects, which will be initiated during the of adobe buildings in the New World, while "Mudbrick second part of 1984 in Chan Chan. Architecture" (Centre Georges Pompidou, France) dis- played photographs of earth architecture throughout With great satisfaction, the organizers of the Symposium have taken note of the work undertaken the world. Trips to Cusco and Chan Chan gave the par- since the meeting by different participants. During the ticipants a chance to examine Colonial and Pre-Hispanic first part of 1984, fifty mudbrick houses, destined for adobe buildings and the problems confronted in their lower-income families, were built in Lampa, Chile by the structures and surfaces. The conservation methods ap- local municipal government. Sergio Rojo (Chile) , one of the lecturers at the Symposium, acted as structural plied were analyzed and evaluated in each case. An afternoon at the Structures Laboratory at the consultant for this project. In , a working group School of of the Catholic University has been set up to analyze mudbrick conservation of Peru provided a chance to see the experiments techniques at a national level. A group of young Pe- being carried out by a team of experts headed by I. ruvian architects, accompanied by the painter F. de Vargas, to achieve seismic-resistant structures and . Szyszlo, visited Hassan Fathy in Egypt and exchanged information about the technology of adobe. Cooperation The members of the Symposium were received in links have also been established between North Africa the by the . and Latin America for the exchange of specialists in Fernando Belaunde, an architect himself, who lectured adobe conservation. on the history of adobe in Peru and throughout the Funds provided by the ICOMOS Committee on , and later showed the participants the different Mudbrick Conservation to 1CCROM have made possible housing projects in the . the publication of the exhibit: "Adobe in America. Its In and around Lima visits were made to several History, Conservation and Contemporary Use", mounted archaeological adobe sites, including the temple-complex by the UNDP/UNESCO Regional Project on Cultural of Pachacamac, the Huaca Juliana and the palace and Heritage during the Symposium. This exhibit, now in museum at . the form of a book, has been distributed internationally.

16 This same photographic exhibit has travelled to place in that country during the middle of this decade. , Brazil and during the present year. This meeting would discuss scientific progress in this In 1985, it will be shown in Spain, while the Georges field and would establish an inventory and study of Pompidou exposition on adobe architecture has travel- the typical endogenous technologies used in the con- led to , Brazil and Venezuela. servation of adobe and other types of earthen build- The Symposium received wide publicity in ings, both ancient and contemporary, in order to give 1CCROM's Newsletter N? 9, where a detailed account of them an appropriate use in present-day society. the events was given. Conclusions and Recommendations of the Symposium were presented to ICCROM's General Closing session Assembly which took place in Rome in May 1984. The Conclusions and Recommendations presented by the Symposium (see below) were read and adopted Venue and date of next meeting at the last session, held at the headquarters of the Andean Pact (Acuerdo de Cartagena) where the Min- With satisfaction, the Symposium took due note ister of Housing of Peru, Mr. Javier Velarde Aspillaga, of the offer made by the representative of the Re- officially closed the Symposium and presented the public of Senegal that a future meeting on adobe take participants with certificates of attendance.

17 H9i:: ~. G]:c Introduction to the Historic Use of Earthen Building Materials. Case Study: Mesopotamia

Andre Stevens

Summary to devise the most varied architectural forms for it, without necessarily feeling constrained by its nature, From antiquity, much use has been made of raw so often considered poor and weak. Even the most earth —a material covering three quarters of the dispassionate observer could not help but be moved by earth's surface— from Mesopotamia to Egypt. In Europe, this inscription found at the base of a in raw Africa and the Middle East, Roman and then Muslim earth near Cairo: "Do not disdain me when comparing civilisations built in earth, as did in Asia the civi- me to of stone: I am as high above them as lisation of the Indus Valley, the Buddhist monks and Jupiter is above the other gods, for I was built in the empires of China. In the Middle Age, this material bricks made from the at the botom of the lake". was still used in Europe, as it was in North America This paper, which addresses a public from widely by the Indians, in Mexico by the Toltecs and the Aztecs, varying backgrounds, seeks to fill a gap too evident in in Peru by the Mochicas. the in general. The subject is For more than 10,000 years, earth has been used of such breadth and scope that we must perforce narrow to raise monuments both prestigious and appropriate it down. Thus we shall particularly emphasize the to the material and spiritual development of communi- ancient sites of Mesopotamia (, , Akkad, Ba- ties. Warehouses, , pyramids, churches, mos- bylon, Assyria) covering 4,000 years of monumental ques, monasteries, palaces, stupas: all sought to use to architecture in earth beginning well before the in- the best advantage the resources of this material and vention of writing in Sumeria.

19 1. (Adobe) a more secure fit, especially in chaining at an angle. Brick has a long . This method was universally adopted and long retained. Supple earth, rich in , was first used in un- In the temple of Eridu, at the same period, the foun- formed rubble. This primitive technique appeared for dation bricks were of larger dimensions than those of the first time in the eighth millenium in the proto- the walls — 43 x 13 x 7 cm as opposed to 28 x 23 x 6 cm. installations at . These "primitive At Uruk, the more recent constructions —such as bricks" took the form of balls of clay grouped around the white temple, built around the middle of the 4th low ridges or mounds, which formed the basis for light millenium — used a small sectional square brick varying construction. We can see at this same site that the from 16 x 6 x 6 cm to 24 x 10 x 10 cm (called following era was already in possession of real brick. Riemchen in German). In the following period, the In the first phase (around 6,800 BC) round houses section was rectangular, 28 x 14 x 8 to 9 cm (Flach- were constructed out of raw bricks, formed by hand ziegel) ; certain sections were much larger, with sides of 80 cm and called hogbacked bricks (en dos d'ane). The (Patzen). base was level, the upper side quite well rounded. The normal evolution of raw brick, which had In the second phase, around 6,250 BC, houses stabilized around a geometric form of regular propor- were rectangular, their walls and floors covered by a tions, was interrupted at the beginning of the 3rd mill. thick coating of purified clay, smooth and coloured. by the appearance of a more primitive form. This newer Bricks now took the form of a quadrangular prism with method is known as the 'plan-convexe' or flat-convex irregular edges. Deep thumb impressions on the surface brick. The upper part was distinctly rounded and was serve to strengthen the adhesion of the . These marked by finger prints or by ripples formed by the were called "thumb-impressed bricks". edge of the hand. The first flat-convex bricks were found at Tello in the last century. Since then, at nearly We note also the use of plain lumps of clay, every Mesopotamian site, they have coincided with the joined together by a mortar of mud mixed with dry ruins of the proto-dynastic era. They have not been grass, in the ruins of the first neolithic 'village' of found at Mari, where the pre-Sargonic temples were still Hassuna, in Iraq, in the 5th millenium. We find renewed built with flat bricks. The flat-convex bricks disap- use of bricks with digital impressions on the Iranian peared at the time of Sargon of Agade, around 2,350. plateau, at Sialk. Brick was used there for foundations The special fitting of these bricks has been studied and floors, while walls were constructed in mud. with precision at the sites of Diyala. The flat-convex Moulded brick, packed by hand into open bricks could be baked, but this was done almost ex- moulds, appeared toward the end of the 5th millenium, clusively for the construction of pits, basins, canals, in the north of Mesopotamia: At Chagar-Bazar, they pavements and baseboards. measured 22 x 20 x 7.5 cm, at Aswad 33 x 33 x 10 cm, at Sialk 30 x 30 x 10 cm. Before 2800 BC, moulded We find in the Sargonic era the return to the brick, level and in more or less regular geometric forms, use of flat brick, alternating with large square bricks was the common construction material, varying only in or half bricks. Later, quarter bricks, bricks in the form size or dimensions from one site to another. of archstones, corners and circle segments appeared. We come finally to the glazed brick, arranged in frie- At Tepe Gawra, in the middle of the 4th millenium, zes cr in vast panels as at or Susia, which unbaked bricks were of excellent quality, and were spread a symphony of colour over the previously drab secured by a mortar of soil and ashes. Their dimensions walls. were 36 x 18 x 9 cm, 48 x 28 x 10 cm, or 56 x 28 x 14 Often built in unbaked brick, Mesopotamian ar- cm. This rectangular format used half bricks at the chitecture needed much protection and consolidation. same time as whole square bricks. The alternance of This double requirement was met in turn by innumerable two formats of identical proportions, by facilitating the cones of coloured baked earth planted in clay, by placement of cornerstones (carreaux boutisses) assured baseboards (orthostats) of stone reinforcing the walls,

20 by gigantic baseboards (plinths) ornated with bas re- exclusive use conditioned the subsequent development liefs, finally by brick panels glazed with colour. Large of construction, imposing form, proportion and use, panels of glazed brick appeared in the second mil- was alluvial earth, the clayey silt deposited on the lenium, but it was only a few centuries later that they Mesopotamian plains by the Tigris and the Euphrates. constituted the richest decorations of palaces and Wood and stone nonetheless had some role to play in temples in Assyria, Babylon and Persia. There were then constructions of brick. veritable 'tableaux' in glazed brick, effected on level Adobe imposed its characteristic form on the clay surfaces, and there were also, in another style, Mesopotamian edifice — great masses with thick walls uncoloured bas-reliefs in brick. On the brick columns of and a few narrow windows. Adobe is a material which Uruk, and Tello, at the 4th and the beginning of does not allow the builder to cut any corners. Orna- the 3rd millenium, slender cones of baked earth, their mentation has to be sober and form part of the con- bases tinted in red, white or black, were planted in struction. Here the wall is master: seen from the close set rows, to the point of covering the columns outside, the monument —house-palace, temple or completely in bands of colour. Their purpose was at — is a perfect expression of its internal once to decorate and protect the surface. At Obeid, structure. Its structure expresses its function. But the columns in the form of trunks of palm trees framed use of brick —especially of raw brick, used for large- the entrance to the temple built in the 3rd millenium; scale projects— has a number of drawbacks. The their surface covered with triangular laminations of building should be resistant to deterioration and pres- shell fixed in asphalt. sure from arching roofs. Builders provided meticulously Documentation is abundant on the innumerable for the risks of erosion and seepage —with drain pipes, uses that the Mesopotamians made of 'solid asphalt' in gutters, beds of reeds, asphalt joints, wall clamping, all its forms: We can say that their country is the only and so on— shcwing a precise sense of precaution. At one in the ancient Near East which has, throughout its Uruk, the oldest constructions rest on platforms made history, consistently employed this product in nearly of brick placed on beds of reeds and swamp grass. every technical domain. But it was above all as an alternating with layers of clay. adhesive, or cement, and as water-proofing that asphalt Foundations could be constructed by layers of found its most wide-spread use over the centuries. At bricks —baked or unbaked — protruding from the upper Ur, in the beginning of the second millenium, the mauso- parts of the wall. These foundations sometimes formed leum of Btir-Sin was built out of bricks and asphalt - its genuine socles or pedestals, as at Uruk, for the "white arch had not budged for four milleniums when it was temple" of the god Anu, which was built on terraces. re-discovered in 1930. In the neo-Babylonian epoch, The laying of flat-convex bricks was more in the middle of the first millenium, asphalt was even complex. Bricks were either laid horizontally — the used, jointing layers of bricks, covering them in long level side of the upper brick placed on the convex side sheets, and so on, to 'macadamise', as it were, the of the lower— or laid in a chevron pattern processional routes of the gods and their faithful from (en epi) as at Tello. The chevron layers were almost always one temple to the next. Asphalt was also used to water- intersected by even beds of bricks. But bricks laying proof floors, pavements, roofs and partitions, whether en epi is impossible with openings — at the approach of stone, brick, gypsum or wood. of doors and angles appear massive horizontal layers of brick. These more stable constructions, most likely laid previously, also served as supports for the struc- 2. Construction ture in chevron. This mode of bricklaying disappeared Architecture in the Orient made its greatest even before the appearance of flat-convex brick, strides in regions where, paradoxically, the construc- around the middle of the 3rd mill. tion materials par excellence stone and wood, were Whether baked or simply dried in the sun, bricks almost entirely lacking. The raw material whose nearly were habitually jointed with a clay mortar, only oc-

21 casionally with a mortar of lime or of earth mixed with use of brick was moreover limited in range and required cinders. But unbaked brick could also be laid before architects to build in oblong shapes over limited sur- completely dry, without mortar. The layers adhered faces. The largest surfaces have been found in the ruins to each other and formed a solid block. To protect the of the palace of Sargon, at Kharsabad, where some facing of these walls of bricks, they were habitually rooms were as large as 32 m. in length and 8 m. in covered by a coating of earth mixed with ground breadth. or of lime. In the interior, these coverings existed already in ancient times and were often carefully polished and coloured, as in Jericho, Hassuna and Sialk. 3. Architecture The delicate problem of covering was early The art of building came about at the moment resolved in Various ways. The flat terraced roof, on when men abandoned natural or artificial shelters to traversal beams covered by matting or branches sup- settle in one place. The beginnings of architecture are porting a bed of trodden earth, was the easiest and bound up with other developments — the the most common solution. The double-beamed roof with of animals, the growth of skills in agriculture, , tiling was found in Hassuna as early as the 5th mill. and so forth, and above all the appearance The tholoi of Arpachiyah, of Tepe Gawra, were probably of collective living arrangements, first in villages, then covered by a mud dome. The bas-reliefs of the palace in cities. This shift was favoured by the climatic changes of Assurbanipal, at Ninive, sometimes represent the which had put an end to the last Ice Age, from 8,500 image of a city whose houses are capped by a semi- to 8,000 BC, especially within western Asia where ce- spherical flattened dome, or calottes, or by elevated reals grew already wild, and where cows, sheep, goats, cupolas exactly like those to be seen today in the and pigs roamed wild. Whether we speak of the prim- Syrian villages in the regions of Hama and Alep. itive setting of Jericho, or of the villages of Jarmo or Muallafat in Iraqi Kurdistan, the first structures, the The tombs of the first dynasties at Ur were fitted first houses marked the same cultural phase. (The first with cantilevered arches, a procedure requiring no houses following a regular plan were found at Tell es cintre or soffit and creating no tension. The true vault, Sawwan, inside a fortified enclosure, the first known or cradle arch, with slightly narrowing brick and in Mesopotamia). exerting lateral pressure, was probably born in Me- Toward the end of the Tell Halaf period, ap- sopotamia. The Greek geographer Strabon well under- peared the material which was to play an essential role stood that the vault was created in this country "due in oriental architecture — brick. It was used somewhat to the lack of wood". With a soffit in half-circle, or earlier on the Iranian plateau of Sialk, it would seem, slightly elongated, its construction was based on vertical than on sites we have found on the plains. It was first sections placed —from the first sections— at a slant used for foundations and pavements, whilst walls con- in order to strengthen the adhesion of the bricks. tinued to be built of mud covered with a thick coating (This was called a voute en tranches or in vertically of earth and mashed straw (torchis), the whole covered inclining sections). The palace of Sargon (8th century with an ochre red paint. BC) on the site of Khorsabad, has admirably conserved With the generalized use of brick, a new impetus examples of these vaults. We already know the true was given to construction, which became during the El cradle arch or arc clave, used to cover passages and Obeid period a veritable monumental architecture. Now doors. It was at Ur, Tello, Khafadje and Tell Asmar that brick imposed on an edifice form and proportions. In the oldest examples of vaults appeared during the first the south, still marshy but progressively dried out and half of the 3rd mill. Only small cradle arches have had colonised, there grew up alongside the reed the force to survive for our study. The excavations of edifices in brick at Erides, Ur and Uruk, in which we Tchaga Zanbil in Susiania demonstrate, for the 8th centu- can see the prototype of the future architecture of ry BC, a remarkable mastery of the assembled arch. The the whole Orient.

22 At Eridu, 13 temples superimposed indicate the multiple adjoihing rooms. Religious architecture became progressive adaptation of a programme. The temple of progressively more complex. The courtyard was now level 7 — the best preserved — shows us the model of an integral part of the temple in which it was enclosed. an edifice which spread throughout the Near East. The The adjoining rooms also formed a part of this block plan in nearly that of a rectangle, the triple internal which on the outside tended toward simple geometric grouping is underlined by the internal partition walls. forms — oval at Khafadje, square at Tell Agrab, The recess has expanded and occupies the entire back. rectangular elsewhere. The temple became a "house of Two wings flank the central room all along its length, god", sometimes difficult to distinguish from a private divided into multiple rooms which respond to the home. complexities of ritual. With the site of Eridu, we are in a position to speak for the first time in the history One example of civil architecture at the time of of architecture of a sacred architecture. Uruk was the "round house" of Tepe Gawra (4th mill.) , a veritable turret or keep placed at the centre of a In the far north we find at Tepe Gawra (on level fortified tower built on a rise overlooking the plain. 13) a temple identical in conception. It is at this epoch Even the plan alone evokes the power of this circular that we also find an element of decoration which shall construction (19 m. in diameter) : the walls, one metre remain one of the distinctive traits of Mesopotamian thick, were built in massive unbaked bricks (50-56 x architecture: on the outside, sometime on the inside as 26-28 x 10 m.). Royal palaces were also based on the at Tepe Gawra, long brick walls are intersected by the plan for meridional houses; the main body on the house regular alternance of simple or compoud projections, built around a central courtyard. By the simple juxta- sometimes even forming profound recesses which break position of units, we come to the large ensemble in up the monotony of the surface. which each part develops organically in function of its At Uruk we find the most representative monu- destination. The palaces of Mari and Kish (2,700 BC) ments of these new tendencies: construction on a large provide an outstanding example of this. scale, sanctuaries elevated on artificial terraces. At The golden age of architecture in the ancient Uruk, eight successive temples were erected on an Near East was the end of the 3rd mill. Its most signif- embankment which measured originally 9 m. in height. icant accomplishment was certainly the famous edifices The platform was raised at the same time that new known under the Babylonian name of ziggurat. Taking structures were built on the ruins of the previous ones. the form of a tiered tower, they were usually temples At last, the enormous was enrobed in a mass dedicated to the principal god of the city, but their of unbaked brick formed in slopping walls, ornated by precise symbolic meaning still escapes us. The con- projections. We find the terraced temple at Uquair, struction of these enormous superimposed terraces cre- and also much further north, at Tell Brak in the ated enormous problems for Sumerian architects, problems Khabur valley. It was from these sanctuaries on a of weights, pressures, setting, consolidation, water platform that derived a seemingly related structure, the seepage, access... Brick, the only material at their dis- ziggurat, which is a sort of tiered tower. The archi- posal, only added to their difficulties. The care which tectural vestiges of the ziggurat only appear with they lavished on the laying of foundation beds, jointing certainty at the end of the 3rd mill. them with asphalt, the incorporation of mats of reeds, The main innovations concerned the 'temple' com- of beams forming a clamp at the interior of slid plex. At Khafadje the successive stages of sanctuary masses, the abundance of drains, of gutters — all these building reveal the junction of a courtyard with the indicate their own consciousness of the difficulties building proper. The courtyard became little by little faced. The ziggurat of Kurigalzu (app. 1,350 BC) situ- one of the essential components of the new temple. ated not far from Baghdad, presents even today an The sanctuary was relegated to the back of the open- impressive central core, revealing its original structure aired surface which was soon to be surrounded by (height app. 57 m.).

23 At the beginning of the second millenium, Me- In 539 BC, at the taking of Babylon, the Persians sopotamian architecture was in possession of principles were welcomed as the liberators of a people subjected and means, which remained constant in the following to the kings of Syria and Babylon. centuries. We find in Assyria (Assur, Nimrud, Ninive, Khorsabad), in Elam, and in the Babylon of Ne- buchadnezzor ziggurats and Sumerian temples. The war- rior kings of Assur, steeped in the colossal, transformed 2. Construction cities and palaces (the palace of Assurnazirpal II at L-shaped bricks: placed at the angles of certain Nimrud, or of Sennacherib at Ninive) into citadels structures have been found at such sites as Mari and bristling with towers and enclosures. But the laws and Larsa, and rounded triangular-shaped bricks have been methods of construction remained practically un- found in the circular supports installed in the ziggurat changed. After flourishing for more than 2,500 years, of Tchoga Zambil. the Mesopotamian civilisations fell into a nearly total Patzen: a type of brick (80 x 40 x 16 cm) used oblivion. in terraces and ziggurats. Riemchen: bricks measuring 20 x 9 x 9 cm, used at the time of Uruk II — IV (3,200-2,900 BC). Flat-Convex bricks: 2,900-2,400 BC. Reeds: their resistance to decay and rot made Notes them useful in solid masses of bricks: they were used in matting, inserted between layers in order to prevent 1. Cultural eras in Mesopotamia masses from slipping. They were also used for a better distribution of weight and the righting of supports Proto-historical periods Hassuna — First half of the 6th millenium Samarra — middle of the 6th millenium Halaf — from 5,500 to 5,000 BC Bibliography Eridu —from 5,000 to 4,500 BC C. Baudez, P. Reichlen, J. Bottero, M.J. Steve, J. Vercouter, Obeid — from 4,500 to 3,500 BC L. Hambis (et autres); Dictionnaire archeologique des techniques Uruk — from 3,500 to 3,100 BC (Editions de l'accueil, Paris 1963 et 1964). J.L. Codivier (et autres); Atlas d'architecture mondiale Djemet-Nasr — from 3,100 to 2,900 BC (editions Stock, Paris 78). Around 3,200 BC, the Sumerians, who had re- J.J. Norwich (et autres); Le grand livre de l'architecture cently settled in Mesopotamia, invented writing. For mondiale (Elsevier Sequoia, Paris/Bruxelles 76). Wonders of the Past (Sir J.A. Hammerton, The Amalgama- 2,500 years, cuneiform writing kept its syllabic and ted press limited, The Fleetway House, London 1930?). logographic character with nearly 7,000 characters. It J. Dethier; Des de terre (CCI, Centre G. Pompidou, was only with the Persian era (5th century BC) that Paris 81). this writing became alphabetic, with 41 characters. J. Verite, E. Ga/dieri (et autres); Rapport sur le 3eme colloque international sur la conservation de l'adobe (Ankara 80). Ruth Whitehouse; The First Cities (Phaidon, Oxford 77). Historical periods Paul Lampl; Cities and in the Ancient Near East (George Braziller, New-York 68). Era of the ancient dynasties — from 2,900 to 2,340 BC P. Amiet; L'art antique du Proche-Orient (Mazenod, Paris The Agada Empire — from 2,340 to 2,150 BC 77). The Sumerian renaissance — from 2,150 to 2,000 BC G. Bunnens, A. Finet, M. Lebeau, A. Stevens, P. Talon (et The first Babylonian dynasty — from 2,000 to 1,595 BC autres); Les fouilles beiges du Tell Kannds en Syrie (Musee de The Kassites — from 1,595 to 1,155 BC Mariemont, 83). J. Margueron (et autres); Emar: un royaume sur l'Euphrate The Assyrian Empire — from 1,100 to 612 BC (Reunion des Musees Nationaux, Paris 82).

24 S.N. Kramer; L'histoire commence à Sumer (Arthaud, Paris du 3ème colloque international sur la conservation de l'adobe, 75). Ankara 1980). K. Khasai; De Sumer à Babylone (Crédit communal, Brux- Aménagement du parc archéologique de Babylone, avec elles 83). application au temple d'Ishtar (Rapport du colloque international Sumer, Assur, Babylone (Neue Galerie, Sammlung Ludwig, sur la conservation, la réhabilitation et le recyclage, Québec, Univ. Aix-la-chapelle 79). Laval, 1981). E. Strommenger; Habuba Kabira (V.P. Von Zabern, Mainz Idem (Akkadica, périodique de la Fondation Assyriologique am Rhein 80). G. Dossin, Bruxelles mars/avril 1980). O. Aurenche; Dictionnaire illustré multilingue de l'archi- Earth Building in China (Architectural Journal of China, tecture du Proche-Orient ancien (Maison de l'Orient méditerranéen, Pékin N9 11, 81). Lyon 77). Les Temples sumériens du Tell Kantuis, et, Aménagement M. Petit (et autres); Histoire générale des peuples, de des sites culturels en terre crue (Lorsque la Royauté descendit du l'antiquité à nos jours (Librairie Larousse, Paris 1925). ciel, ou les fouilles belges du Tell Kannäs en Syrie, Mariemont et G. Roux; Le mystère de Sumer (Revue 'L'histoire', Paris, Louvain-la-neuve 1982). mai 82). Le Devenir des sites culturels dans l'espace méditerranéen J.C. Perpère; Les cités du déluge (France-Empire, Paris (Perspectives méditerranéennes, Fondation postuniversitaire inter- 79). culturelle, Paris décembre 1982). Agatha Christie; Meurtre en Mésopotamie (Club des mas- Monuments et sites de l'oasis de Turfan sur la route de la ques, Paris 67). Soie (Monumentum, York 1983). Case Study China; Earth Construction Technologies Ap- propriate to Developing Countries (Rapport HABITAT et K. Uni- André STEVENS/Bibliography versiteit Leuven, à paraitre). Publications de photographies dans les revues ou catalogues: Les Palais Royaux d'Abomey (Rapports techniques publiés Le Courrier de l'UNESCO, Monumentum, Des Architectures de par l'UNESCO en 78 et 79; NIQ FMR/CC/CH/78/107 et FMR/ Terre, Akkadica, Architectural Journal of China, La revue de la CC/CH/79/ 103). céramique et du verre, Plus ou moins zéro, Vlaanderen Erfsgoed, Sauvegarde des palais royaux d'Abomey au Bénin (Rapport Le Soir, Lorsque la royauté descendit du ciel, etc.

25

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-74 Conservation and Use of Historical Centres and Monuments

Franca Helg

My contribution to this Symposium will be limited The need to renovate was in the air, to build to the problems concerning the conservation and use any which way, to obtain the maximum immediate of historical centres and monuments. profit. Thus, to the catastrophe caused by war or by That which has been built: cities, isolated towns, the earthquake was added the disaster caused by a the countryside —cultivated or contemplated— stand hasty reconstruction, unplanned and based on myopic as witness to the history of man and, in our daily concepts of speculation or economy. uncertain existence, this centuries-old testimony con- The centres of the cities hit by the war, the tributes significantly to our will to live and to do. areas devastated by bombs, were rebuilt without any Indeed, it is in the continuity of tradition that attention to existing typologies or to the morphology our own roots lie, as well as our awareness of universal of the city. values, and of those specific to our ancestors. The volume of the context was disregarded; no Nonetheless, in moments of great perturbation, effort was made to insert new buildings harmoniously these values are not always felt or taken into account. in the pre-existent ensemble. In the highlands devas- Such is the case of Italy, after the great de- tated by earthquakes and natural disasters, recon- struction caused by the war; such is also the case struction took place without any regulation or character of Peru after the earthquake. as well. The vital need to surmount the disaster left no While the old cities represented an element of time for reflection. It was necessary to build, and to cohesion, the new cities were transformed into an do so with scarce materials. element of alienation.

27 In Europe and, more specifically, in Italy, the hance") "as before and where before" — not taking economic boom of the fifties and sixties caused ravages into consideration the fact that things change daily. in all our cities and in the more sought-after tourist Building techniques, materials, manual labor, locations. new customs, contemporary quality of life, the ever- Autocriticism concerning these actions and the growing city and the qualifications of its inhabitants - historicism characteristic of our cultural moment have all these things require new solutions and new inter- given rise to a revision movement, which is important ventions. At the same time, we know too, that it is and articulated in a complex manner. necessary to maintain a continuity with our recent and Authorized persons —both critics and decision— less-recent past, and to revalue the vestiges of the making officials, have stated the following: civilizations that went before us. 1. it is necessary to preserve all that which is pre- An Italian philosopher of the XVIth century, Gior- servable. dano Bruno, believed the culture of the last civilization 2. a monument —be it of outstanding quality— loses to be the sum of the culture and experience of our part of its significance if it is not inserted in its own ancestors. To it is added contemporary progress. context. This context must preserve its character and Indeed, today the object of our concern and be a true "history-book". attention is not only the isolated monument renowned 3. the city, the urban conglomerate, is a common good; for its historical value or significant because of its as such, it must be used and enjoyed by all the com- artistic merit, but the total context. We cannot think munity. of integrating a monument in its context, however, These lucid statements are followed by more without taking into account the needs of contemporary schematic "slogans". One of the more diffuse ones life, for it is erroneous —from the point of view of states that the less favoured sectors of the population cultural progress— to renounce to the expression of should "re-appropriate" the city — that is, those sectors contemporary language. which the capitalist city tends to displace and expulse The ancient cities —as Leonardo Sciascia, the towards the periphery. Italian writer says: "the cities where the past of man The battle which ensued over this concept was lies in every stone"— are stratified due to successive very fruitful and contributed to: contributions, and their significance and message lie a. create an awareness in the public regarding issues precisely in these rich and multiple strata. Our own upon which the common man had ceased to reflect. contribution must also become a part of the history b. induce politicians and the legislative powers to stop and character of the context. speculation. This constituted an important cultural and politi- The problem is how to intervene — and we know cal operation which, once more, stated the need to that it will be different in each case and in each save historic centres in an integrated manner, as wholes. situation. Nonetheless, it will always be necessary to ... And all the world spoke of Bologna and Ferra- find an appropriate function or use for a building, ra and Venice. But, in truth, very little of what was to which can be carried out without damage to the edifice be expected was done in Bologna or Ferrara or Venice. and which will, at the same time, guarantee its vitality. The partial failure in the operative phase is due —in If a historic centre is not intensely vital, it becomes, my opinion— to three causes. in a few years, a ruin. Possibly, special adaptations are to be made, 1. Deficient legislative and administrative instruments, necessary to the new function. Often, the building must which hindered public intervention. be equipped and fitted with contemporary installations. 2. Imprecise intervention plans, which delayed their In my view, every intervention —apart from execution. being reversible, when this is possible— should have a 3. An erroneous will to rebuilt (or restore or "en- contemporary character and should be done with a

28 light hand and with respect for the character and by relating what I have previously expressed specifi- nature of what pre-exists. The volume, height and cally to architecture built with earth. shape of spaces should be respected and merit close It has been said that adobe is a "poor" material: attention. In a historic complex, inserting a tall I do not believe we can accept this limiting definition building will destroy the whole of the context, while if we bear in mind the long span of time throughout this will not happen if buildings of a scale similar to which adobe-building techniques have been developed, the existing ones are inserted within the historic as well as the wide geographic distribution of this texture, even if they are built following contemporary building tradition. There is poor architecture and no- norms. ble architecture: it is not only the quality of the ma- The experience at Bologna, where "voids" in the terial, but proportion and character which lend solem- medieval context were rebuilt and town-houses were nity to architecture. restored servilely following medieval shapes with mod- In Peru, as in Morocco, , or in Saudi ern materials and techniques, seems to me very naive. Arabia, there are rich and solemn buildings and com- Eaves, for example, were built using concrete beams for plexes built in adobe; often, surrounding them there support, made to look like the ancient wooden ones. is (or was, unfortunately) a group of minor buildings, The result is one of imitation, with little value, except perhaps poor ones, that, nonetheless, constitute a for a poor scenographic effect. context charged with vitality which enhances the value The windows are shaped like the old ones, but and significance of the larger complex. to improve (according to contemporary criteria) hy- In many countries, as a result of an eagerness genic conditions, ventilation and insolation, they have to "modernize", devoid of any good judgement and been made larger. Proportions change, and the whole only looking for "change" in customs and in technology, looks inharmonious and false. There was a will to as well as a result of an uncontrolled desire to increase maintain the character of the whole —which is com- real-estate profits, "mcnuments" have been surrounded mendable— but the error was to think that past styles by anodyne buildings of shining glass or plastic ma- and shapes can be repeated and rebuilt without more terials, dissonant among themselves because of their ado. This results in stylistic falsity and turns these difference in volume and proportion and, even more buildings into something surfeited and devoid of value. so, dissonant with the monument. The Municipality of Bologna studied, researched In the traditional centre of Riyadh, in the and understood in depth the morphology of the city highlands of Najdi, in Saudi Arabia, today almost noth- and the existing interdependence between residential ing is left of the pink city, rich in fascination, which and civil architecture. The result should have been a voyagers from the turn of the century describe. It was proposal to complement the old texture of the city with a city entirely built in raw earth; its architectural buildings whose volumes would respect the context, typology and morphology were perfectly harmonious and and would be harmoniously and carefully inserted in adapted to the climate and lifestyle. This city endured it while at the same time being an expression of con- until the oil boom — today, however, only the Masmak, temporary "architectural language" and technology. in the centre of Riyadh has withstood the "renovating" When completing missing parts in old buildings destruction. that have become slums, one must be attentive and Our architectural offices were in charge of the sensitive to ancient colours and materials, yet one must restoration of the Masmak. It was necessary to deter- also be conscious of the fact that modern materials mine in situ, on the basis of very few existing do- can be added next to the old ones and that, by af- cuments, and by analogy with similar buildings, what finity or by contrast, an interesting expression may be the original shape had been, what had been added achieved. rationally and which parts were fake. We carried out I might continue giving other examples; however, a study (with the collaboration of Professor Giacomo given the nature of this meeting, I would like to end Chiari, from Torino) in order to improve the chemical

29 and physical endurance of raw earth. Then we pro- terpreted following the healthy norm of "case by case". ceeded to restore the complex, using traditional meth- We must respect "tradition", and tradition im- ods; we were able to turn to the surviving craftsman- plies the collective awareness of the continuity between ship of the Bedouin laborers, experts in adobe, and present and past; it means a continuous integration we had access to the appropriate material for the between the ethical and cultural values of all times; fabrication of . it means a collective recognition of the permanent cul- Restoration was completed by installing the tural values. Yet, at the same time, we must bring necessary electrical fittings, as well as by providing it tradition "up to date", according to the criteria, the with water and sewage — obviously using contemporary ideology and the opportunities of today. materials. In certain conditions of economy and productivi- The restoration —including new installations— ty, in certain geographical latitudes with climates was done in view of establishing in this complex a having a wide range of thermic variation, in the pre- Historical Museum, following the instructions of the sence of adequate materials, etc. it may be reasonable Minister of Culture of Saudi Arabia. to propose again —and once more— the ancient tech- Restoration was, in our opinion, satisfactory: nique of building with earth. Adobe, its building tech- we do regret that this "palace-fortress" is now sur- niques, its formal characteristics, its appropriateness in rcunded by a city without character. This diminishes view of existng conditions and the lifestyle of the the value of the building and makes it look anachronic country, constitutes an important element in the conti- —which leads us to reflect upon the artificiality of nuity of tradition and represents a search for the this type of conservation, limited only to one vestige expression of ethnic identity. On the other hand, the of the past. styles and architectural typologies must evolve in a There was an opportunity to restore the entire manner coherent with our times. city — and it was lost. A regulating plan had been All restoration work must be done taking into established by the architect Doxiadis; it was rather account two poles, respect for and interpretation of schematic and rationalist — but there was no "pro- tradition, and the contemporary quality of life. The gramme plan" to restore the whole of the city, to adapt sclution to this problem means keeping alive the tech- the old earthen houses and to complete those missing niques and the craftsmen who know how to build with parts, already destroyed, using contemporary technlo- adobe; to continue studying consolidation techniques gy. This completion of missing parts should always be which will reduce the cost of maintenance of adobe done with respect and atention to pre-existing volumes, throughout time and to undertake studies and propose taking into account the density of the urban texture, plans to introduce into this ancient technique the es- so that the new buildings be in a harmonious relation sential technological elements of contemporary civiliza- with the context. tion, such as electrical installations, water and sewage Even within the general framework of the Venice systems, and air conditioning. Charter, restoration methods vary, according to what I believe it is necessary to take into account is to be restored: whether remains, ruins or monuments these different needs, and to adopt solutions which will of great historic or artistic value, or whether restora- not damage the solemn and at the same time elemental tion implies contexts of more modest characteristics. It character of adobe, while allowing an autonomy of is obvious that the general principles must be in- design in contemporary buildings.

30 Characterization of Adobe as Building Material. Preservation Techniques

Giacomo Chiari

Introduction procedures should be selected. A complete study tending to determine the causes of deterioration of The study of adobe as a bulding material for adobe involves obviously much more work than an en- conservation purposes is fairly recent with respect to quiry to establish if a given soil is adapted to produce other branches of conservation. Work has been done good adobes, compatible with those of a historic in the last decades, but we still need standard test damaged wall. methods for characterizing the relevant physico-chemi- A complete chemical, mechanical and mineralogi- cal properties both for the soil to be used to make cal characterization of soil is a difficult task, since new adobes and for the mud bricks of historic buildings. beside humus, the mixture of mineral components of (Clifton, Brown and Robbins (1) made a relevant con- soil is, in general, very rich. The mineralogy of clay tribution in this direction and in this review I will minerals is in itself fairly complex. However, simplified extensively refer to their work). Also standard pro- procedures of tests and analyses could be useful in cedures to assess the effectiveness of protective inter- determining the most important properties of adobe. ventions (from surface treatments to structural repairs) especially in connection with its conservation and will are very much needed, not to talk about the conser- be briefly described here. vation techniques themselves. A review of the causes of deterioration for dif- The analysis of adobe soil or bricks may have ferent climates and building typology is attempted. several purposes, and according to them, different together with some suggestions for possible conserva-

3 I tive interventions. Many of the techniques applied for and binder is between 60 to 80 percent , 20 to 40 this goal are still at experimental level and sometimes percent silt and clay, and little or no gravel present (1) . controversial. A critical evaluation will be attempted, hoping that it will provoke a profitable discussion. One should keep in mind that no final solution has been found yet to the problem of conservation of adobe; and 1.1 Clay Minerals one can seriously doubt that some recipe will ever be Being the binding agent of adobe, the clay found to fix in time the conditions of a mud structure. fraction is particularly important. Clays are metamorphic All we could hope for is to find ways of slowing down minerals formed by atmospheric weathering of many to acceptable rate the processes of deterioration which, types of rock. Clay could be chemically classified as for adobe materials, are very rapid. aluminosilicates hydrated; some contain as major com- ponents sodium, potassium and calcium; in other iron and manganese may substitute aluminum and silicon in the framework. 1. Classification of soil in terms From the structural point of view a large part of particle size of clay is amorphous or shows a low degree of The particle size distribution of an adobe is a crystallinity. When crystalline, clays present a layered very important piece of information related to the structure: the silica layer is built up by tetrahedra behavioural characteristics of the material and its dura- containing Si at the centre and oxygen or hydroxilic bility. The granulometric analysis is not too complicated groups (OH) at the corners. These layers can be joined and does not require sophisticated laboratory equip- together in different combinations, can accept inter- ment. Therefore it should be one of the first to be stitial positive cations (to compensate for the lack of performed for adobe characterization. For our purposes positive charge due to iron-aluminum substitution), and the particle size distribution curve is normally broken water, giving rise to the various clay families (e.g. down into four sections: kaolin, illite, montmorillonite, chlorite). Water can pen- etrate between silica and alumina layers forming a net gravel : particle diameter larger than 2 mm. of hydrogen bonds and surrounding the interstitial sand : particle diameter between 0.02 mm. (20 mi- cations. This causes clay in the presence of water to crons) and 2 mm. become more plastic because the layers can slide easily silt particle diameter between 2 and 20 microns. over one another; if more water is added, the platelets, clay particle diameter less than 2 microns. completely surrounded will be dispersed, passing freely in suspension. A small amount of water causes swelling Gravel and sand are considered to be the in the direction orthogonal to the layers, with corre- filling material. They consist normally of minerals rath- spondent contraction upon drying. This happens in er resistant to weathering such as quartz, feldspars, different extent according to the type of clay. Kaolin, mica, calcium carbonate, etc. Each grain has good me- for example, does not expand because water cannot chanical properties but no coherence is ensured among penetrate between layers (2), (3). On the other hand different particles. The binding elements are clay and sodium montmorillonite can increase its interplanar dis- to certain extent silt. Clay particles, especially in tance orthogonal to the layers from 9.6 to 21.4 A. The flocculated form, adhere well to each other and to the other clay families show intermediate behaviours sand, keeping the adobe together. Clay, as we shall toward water. see, tends to become more plastic and to swell with It is generally accepted that for conservation increased water content. Conversely the excessive purposes the precise identification of the clay type is shrinkage upon drying of pure clay causes cracks. For not necessary, with the only exception perhaps of so- good adobes an optimum compromise between filling dium montmorillonite, which for its tremendous swelling-

32 contraction properties, should be avoided in the man- time in cm/seconds is plotted against the particle di- ufacture of new adobes, to eliminate cracks. ameter in microns for various temperatures allows to determine the appropriate settling time. A series of sieves can now be used to separate 2. Types of analyses available for adobe, the coarser material (see (1) for detailed number of and critical evaluation of the sieve-size opening correlation). The material catched information obtainable by each sieve in the column is rinsed, dried and weighted. The part that goes through N9 400 sieve (38 micron size) contains a fraction of clay-silt of less than 20 microns that should be fractioned by sedimentation 2.1 Granulometry or size and added to the part already separated. Since clay distribution analysis it content is calculated as difference between the total The importance of selecting a sample representa- sample weight and the combined weights of silt, sand, tive enough of the adobe under consideration should gravel and organic material, any loss of material that be stressed. Good solid adobes should always be taken, may occur during the procedure will be calculated as avoiding powdery material or severely damaged bloks. clay. So it is very important to avoid that particles Possibly several samples located in different points of remain entrapped in the sieves, by brushing the in- the adobe structure should be analyzed and results verted sieve with a stiff brush. Also the amount of compared. The mass of the sample should depend on soluble salts determined, as described in section 2.2. the size of the largest particle present; but for should be subtracted from the total amount of clay. historic adobes, sample mass between 150 and 300 grams The separation clay-silt follows the same princi- were found to be adquate (1). ple of sedimentation, only with different, and much The detailed procedure for the size distribution a- longer, settling times. Since for a 2 micron clay par- nalysis is given in (1). Here a brief outline is sketched. ticle the settling time for a 10 cm high column is 8 hours The separation concerning sand and gravel relies on and 20 minutes at 189C (as it can be deduced from sieving, while clay and silt fractions separation relies the normograph), several days are required to properly on particle sedimentation. separate clay from silt. This is only needed if further First the moisture content is determined by identification of clay minerals is planned (in this case weighting before and after drying the sample in oven the clay fraction after long sedimentation should be at 1059C (percentage based on dry weight). The dried at 609C to avoid possible irreversible dehydration). crushed material is then immersed in a solution of so- The granulometric analysis is useful to establish dium hexametaphosfate in distilled water and allowed and, if necessary, to correct the ratio between filling to stand overnight to facilitate the dispersion of clay and binding elements in the soil selected for the man- particles. A filter N9 8 or 10 can remove the larger ufacture of new adobes, to avoid cracks (too much particles and twigs, thus simplifying mechanical stirring. clay) or disgregation (too much sand). Alternative The remaining organic part, less dense than water, much simpler "tricks" for the same purpose will be floats cn the surface and can be removed with tweezers, presented elsewere during this course. weighted and retained for further analysis. To minimize clogging of the finer sieves it is advisable to perform a partial separation of the clay- silt portion by magnetic stirring, followed by dispersion 2.2 Soluble salts analysis in a 8-10 cm high column of water, settlement for a pres- Adobe may often contain appreciable amounts cribed period of time and syphoning of the clay-silt of soluble salts, which may affect its durability by crust suspension (repeat 3 or 4 times). A normograph de- formation, efflorescences, stress due to crystallization, veloped by Tanner and Jackson (4) in which the settling hygroscopicity. Given the large size of pores in adobe,

33 these effects are generally less dramatic than for be necessary (see (1) and references therein; also stone (5). The determination of the amount and compo- (3)). Fortunately for our purposes, the montmorillonite sition of soluble salts is in any way a datum of sig- group which is important to identify for , its swelling nificant interest. The procedure simply consists in proyerties, presents a nice line corresponding to a dispersing in distilled water a weighted dry sample and 151 basal spacing which allows an easy identification, collecting the filtrate (a Buchner aspiration filter may even in the presence of other clays. help). This should be repeated 4 times to ensure As for the soluble salts, since one can guess complete washing. The filtrate, evaporated without their kind and therefore simply check their presence boiling, and dried in oven is then weighted. even in a complex sample, this method is very useful. Elemental chemical analysis can be performed One can establish for example if calcium is present as with a series of techniques. Quantitative data so ob- chloride (hygroscopic) or as sulphate (which is not), tained may be related to the mineral phase determi- and in this case if a gypsum or anhydrite, etc. nation performed by X-ray diffraction and described Another useful application, apart from the com- next. plete identification of the mineralogical components, is a superficial and qualitative comparison between the spectra of a historic adobe and the soil from which 2.3 X-Ray diffraction analysis: new adobes are planned to be made for repairs. Gross the powder method similarities or differences can be evaluated at glance It allows the phase identification of crystalline by an experienced analyst. meterial (semi-quantitative) , but requires sophisticated equipment and trained analysis. 2.4 pH determination Theoretic principles: the angle at which an x-ray pH is a measure of the acidity of a water solution. beam of given wavelength is diffracted is related to It is by definition the inverse of the logarithm of the the interplanar distance d of the crystallographic dif- concentration of hydrogen ions. In distilled water fracting plane. These distances depend upon the unit (neutral) the concentration of H+, is equal to 1/107, cell dimensions and geometry; the intensity of dif- corresponding to pH = 7. A pH of 2 for example fraction is related to the type and arrangement of indicates a strongly acid solution, while pH of 13 cor- atoms within the crystal. The use of finely crushed responds to a strongly basic solution. powder as sample, allowing all possible orientations of The measurement of pH for adobe can be useful crystals of a given phase with respect to the incident because acid solutions (low pH) promote flocculation beam. will produce diffraction cones of specific angular of the clay minerals from suspensions, while a high pH opening and intensity, which can be detected either by can lead to the formation of a stable suspension of a diffractometer (equipped with a proportional coun- clay (7). ter) or on a photographic film. Search file manuals There are suggestions (1) that the pH of repair such as the Powder Diffraction File (6) simplify the materials should be within ± 2 pH units of the original comparison of the actual spectrum with the ones tabu- adobe. lated in the literature. The measurement of pH is very simple. Portable If the sample under consideration is composed pH-meters with batteries are available. Coloured strips of one compound only, its identification is simple and of paper with pH indicators may function equally well straigh forward. The task is more complex if an on the field. admixture of different compounds in different percent- age is present, which produces diffraction lines all 2.5 Colour evaluation superposed. For clay mixtures, owing to the similarity of the unit cells, special techniques as glycolation or The evaluation of colour of adobe in a standard- double analysis after specific thermal treatments may ized way is useful especially when repairs with new

34 adobes haN%e to be planned. The Munsell soil colour is the scanning electron microscope (SEM) which uses charts are available since a long time, and allow the a finely focused beam of accelerated electrons di- matching of colour with 196 different standard colour rected over the sample (which is normally gilded to chips, arranged according to three variables: Hue, be conductive and kept under vacuum) and slowly Value and Chroma. The Hue notation indicates its re- moving in regular lines (scanning) . The secondary lation to red, yellow, green, blue and purple, and is electrons emitted from the sample at each point are symbolized by letters. Value notation indicates the collected, and the picture of the object is then con- colour lightness, and Chroma its strength; they are both structed by electronic devices. symbolized by numbers. The advantages of SEM are the possibility of The use of this standard procedure and its obtaining sharp images up to 150,000X due to the notation allows different researchers in different times large depth of field. For adobe, enlargement of 20X to to check colour variations. 2,000X is more than sufficient. When equipped with a microprobe to obtain quantitative chemical analyses of the fine detail under examination it becomes a very 2.6 Optical and electron microscopy useful piece of instrumentation. The simplest equipment which does not require Given the versatility of its applications, many special expertise from the operator is the binocular universities are now equipped with SEM. microscope in reflected light. It allows three dimension- al, stereoscopic view of fine details. The adobe sample can be a fractured surface, possibly sprayed with col- 3. Causes of deterioration ourless acrylic, or a section polished after impreg- nation with epoxy resin. The enlargement obtainable is of adobe materials up to 100X, although at the levels the depth of field is very low and clear images are difficult to be 3.1 Water obtained for focusing problems. But even lower en- For once in science the simplest, more obvious largements can give a lot of useful information on the answer to a problem is the correct one: by far the microfabric of adobe such as: voids, cracks and pores largest amount of damage to adobe structures is as- dimensions and distribution, possible crystallization of cribable to water, especially when it is abundant and soluble salts inside cavities, grain dimensions, presence in liquid form (rain, water pools). As we have seen, of straw or, even more important, the imprints of straw clay particles in contact with increasing amounts of long after its decomposition. 1 consider this optical water, first increase their volume; then become more examination an essential part of adobe investigation. loose (higher plasticity) and eventually are dispersed The next level of microscopic technique is the in a water suspension. Being clay the binding agent of observation of thin sections (30 microns) with the adobe, this effect is obviously deleterious. Wet clay petrographic microscope in transmitted polarized light. becomes impermeable to water and excess rain runs on This leads to the mineralogical phase determination of the surface, carrying suspended matter, digging pref- the crystals present via their refractive indices meas- erential channels which are eroded even faster since ured by comparison with standard series of oils with subjected to a larger water concentration. Tensil and known indices. The drawbacks are that a thin section ccmpressive strength of adobe are influenced by of adobe is somehow difficult to prepare, and the moisture content up to 200 percent (10). Therefore, analyst should be an experienced petrographer. On particularly the bases of walls which have to support all the other hand, valuable information is obtained, es- the weight, once impregnated with water, tend to col- pecially in the case that x-ray diffraction is not availa- lapse. This effect is particularly evident when, due to ble. rain and poor drainage, or to the rise of the water The third more sophisticated level of microscopy table level, open pools of water can be formed. In

35 many cases one can see arches formed by the collapse 3.2 Earthquakes of the lower part of walls. Complete destruction follows soon. In seismic regions earth movements can be even more disastrous than water. For historic monuments in Upon drying, clay tends to contract with crack formation. Crusts can be formed due to a sort of na- adobe there is very little that could be done to prevent tural sedimentation: The coarser particles are de- such natural catastrophes. For new adobe housing, posited first, forming a layer of very poorly adherent reinforced blocks and better design can improve a lot material. The finest particles, which take longer to the resistance to vibrations. sediment, constitute the upper layers of almost pure 3.3 Sun clay, severely contracting with exfoliation. As a marginal aspect of the clay displacement, a Irradiation does not affect adobe in a direct change in colour toward lighter tones takes place, due way. In combination with water may produce cracks to the fact that on vertical surfaces the platelets are and crusts by helping quick evaporation. If parts of now being deposited with their cleavage plane paral- walls in the shade are suddenly reached by the lel (instead of orthogonal) to the wall surface, thus sun in hot climates, a thermal shock may take place reflecting more light. (changes in temperature of up to 40°C in half an hour). Finally the water movement (in liquid form) Crust detachment can be caused by different from the interior part to the surface of walls during thermal dilation between the surface and internal evaporation, can transport dissoluted salts which may layers, caused both by the thermal gradient and dif- crystallize on the surface (causing white efflorescences ferent thermal expansion coefficients of the various often hygroscopic) or, even more dangerously, im- layers. This should be kept in mind when applying mediatly underneath of it, (it depends on the evapo- superficial consolidation treatments, which should leave ration speed) causing crust detachment with their dilation coefficients of the treated part as close as increase in volume. possible to the untreated one. It should be emphasized that even in those arid countries with very low water fall, the danger of rain 3.4 Wind can hardly be underestimated. Usually, in fact, the rain It can cause detachment of loose parts or be is limited to short torrential storms, which, for their responsible for abrasion, especially if carrying sus- violence, cause more damage than a prolonged but pended sand. Wind may cause indirect damage by tran- weak rain. Torrential rain can act upon the already sporting droplets of sea water (marine aerosols) lead- weakened parts, i.e., the base of walls, by splashing ing to hygroscopic salts incrustations after evaporation. effect, thus subjecting it to the action of drops coming Wind can also increase surface evaporation speed on in two opposite directions. a damp wall, to such an extent that liquid water films In conclusion, rain alone, with its macroscopic cannot be formed on the surface. Evaporation takes effects, accounts for most damage in adobe structures. place immediately below the surface, in the pores; the Rising damp is another less severe but not disruptive effect of salt crystallization is greater, negligible action of water. Even when it does not pro- creating alveoles by loss of material. The wind speed duce water pools, it may produce salt efflorescences. in the alveole is then further increased by the air These are limited to the very bottom of walls (40 to eddy, giving rise to what is called eolic or alveolar 60 cm) since capillarity is not a major effect in adobe, erosion (2). due to the large size of the pores. They affect, though, a part of the walls which is particularly weak. Surface condensation, with cyclical contraction 3.5 Soluble salts and expansion, may cause micro-cracks, crusts or help Although the internal migration of soluble salts the detachment of performed crusts. does not affect adobe as severely as stone or masonry,

36 due to the larger size of adobe pores, it may cause never stressed enough. This is true for all materials, problems. We have just seen the role of salt crystal- but particularly so for adobe, whose weak character- lization in alveolar erosion. If 'the evaporation can istics have always been counteracted with regular take place on the surface, a salt efflorescence, normal- maintenance and extensive rebuilding. The fact that ly white, is formed. These salts, rather hygroscopic, help modern conservators obviously cannot act with the same to trap humidity, with crust formation. freedom in rebuilding damaged parts of historic build- ings, simply means that, on the long range, they are 3.6 Biodegradation: plans and animals condamned. All we can hope for is to enhance their life expectancy. For this purpose some techniques have Not only algae or lickens but also superior plants been proposed, that are reviewed here. can grow on adobe structures, provided that moisture is present. Grass is common in rainy areas. In more arid climates, a few leaves of xerophiliae on the sur- 4.1 Complete immediate reburial face may be supported by several meters of large roots. A rather drastic measure, to be applied to archae- which in their search for water, cause big cracks in ological excavations which are below the ground level. walls. Once decayed they leave holes for preferential It is necessary if some documentary evidence of the water infiltration. excavation has to be preserved for the future. A layer Animal life can cause damage too: birds build of salt free sand may be put first to facilitate re- their nests in adobe walls; in the Andean regions a excavation. A lot of damage may affect not completely kind of wasp digs smaller but more numerous holes for excavated sites during the time lapses between exca- their nesting. vation campaigns. This is a very serious matter, since the semi-excavated affected parts are not yet docu- 3.7 Man mented. Therefore temporary shelters should always Direct human intervention is sometimes responsi- be put in place. They could be very simple and in- ble for the loss of historic monuments, in adobe as well expensive: cane or straw mats covered with mud have as other kind. Wars are major catastrophies, unfortu- been proven effective. nately beyond our control; modern urbanizations, dams More difficult, but necessary, is to obtain an flocding entire regions, even though meant for the efficient draining system because of the impossibility of good, can cause the destruction of entire adobe towns. digging holes or channels in parts which have not yet The presence of visitors in great number may be very been excavated. Perhaps this problem should be con- damaging, and, if a monument should be open to the sidered when drawing the excavation plan. general public, special measures must be taken to in- sure the protection of the structure. Important ar- 4.2 Total protection from weathering chaeological sites can be damaged by illegal excavation agents or mere vandalism. Finally lack of maintenance has been proven deleterious. Sheds and roofing systems have been applied in many cases to protect archaeological sites. They have 4. Possible interventions for conservation been proved to be effective when direct action of rain purposes is the only cause of damage. In the presence of marine aerosol (e.g. Chan Chan, Peru) a shed facilitates con- They tend to reduce the speed of deterioration densation with further damage. processes either by removing the causes of alteration Total enclosures with transparent materials and/or disposing of details which act as catalysts of (glass, plastic panels) should be absolutely avoided, disruption. The fact that no "final solution" is or will due to the establishment of a totally different be available for the adobe conservation problem is micrcclimate and to the greenhouse effect. In every

37 particular case a roofing project should be carefully penetrate the shield, it would easily destroy the un- studied to avoid results that could be very unpleasant treated original material underneath it. from the aesthetic point of view. Cappings have the obvious disadvantage of pre- venting the original part from being seen. Soil cement 4.3 Partial protection cappings, if not properly executed can also be very ugly. Since the new material will deteriorate as well, In general adobe structures brought to light by measures should be taken to identify it as modern; archaeological excavation are incomplete: they are miss- bricks could be marked with the date, for example, or ing the roof, which was originally an essential pro- small glass bits can be inserted. tection. Adobe structures can withstand the effect of 4.5 Should the new adobes be rain only if they present a complete surface rein- forcement, without weak, untreated parts. This can be reinforced somehow? obtained with a series of measures. There is an old debate based on this question. Many people feel that repairs should be performed using strictly traditional materials. It is also true that 4.4 Repairs using reinforced bricks many times, especially if the new adobes are inside the and/or soil cement walls, they do not need to be reinforced. From the If part of a wall is damaged, it is better to take technical point of view repairs made with a material out the ruined bricks and substitute them with new much stronger than the original one should be avoided. ones. In fact the deterioration would continue at the con- Structural repairs should be preferably done with nection surface and at the expenses of the original bricks or pieces of them if the crack to be filled is part. On the other hand, if the new material is exposed not big enough to accept a whole brick. Mud or soil to rain (i.e. in the case of capping) and its mechanical cement filling should be avoided because, after con- properties are not too different from the original, I traction, they easily come apart. In my experience the think that to be able to count on and higher water additicn of a minimum amount of portland cement (less resistance is a great advantage. than 10 percent in weight) can improve a lot the water resistance of the new blocks. 4.6 Drainage systems If the wall presents a section regular enough A proper drainage system should in any case on the top, a capping can be made with one row of be planned. Sometimes, due to the irregularity of new reinforced adobes. If the surface is irregular, a excavated sites, this can be a difficult task. But if capping 3 to 5 cm thick made with soil cement (same heavy rains are expected, drainage is so important proportions) can be applied. that less important parts should be sacrified, if ne- It is better to put one layer, let it dry and cessary. crack, and then apply a second layer, using a slurry which contains much less water. The capping should be well compressed, it should dry slowly (better cover it 4.7 Surfaces treatments with wet straw mats for the first few days) and, most An effective surface treatment has to possess the important, its shape should be convex, to avoid forma- following characteristics: it should confer water re- tion of water pools or preferential channels. If the sistance to the mud surface. That means that the clay capping is a couple of centimeters salient with respect particles should no longer be taken apart by the to the vertical surfaces is better. Cracks that may action of water. appear during the execution of the capping or later A water proofing action, in the sense of render- on should be checked and filled, because if water can ing the surface impermeable to water, is not neces-

38 sarily needed. In effect it can have negative effects The material that up to now seems to fulfill when in the wall there is water coming from other most of these prerequisites is ethyl silicate. After impreg- sources than its surface. In general, if the surface can nation and hydrolysis, the alcoholic part of it evapo- maintain its original porosity an therefore "breathe" rates, leaving a three dimensional network of silica and let the internal humidity evaporate, it is an ad- tetrahedra, which constitutes a series of bridges vantage. between the clay particles, preventing them from be- The physico-chemical properties of the treated coming loose when in contact with water. The fact that surface should be as close as possible to those of the all what remains in the wall of the silica ester is a untreated part. The colour, as well as the texture, framework presenting mineral characteristics, insures should not change much for obvious aesthetic reasons. that the treatment is stable in time, in the sense that For example a glossy surface after treatment is not no further chemical reactions would take place. The acceptable. physico-chemical characteristics of the adobe (colour, Hardness and thermal dilation coefficient should porosity, thermal behaviour) are almost unchanged, not change much as well. In particular, if the behaviour and only water resistance is highly enhanced. Labo- toward thermal change is very different, the treated ratory tests (1 1) showed that after 24 cycles of water part would come loose after a short time, a gap would impregnation by immersion followed by complete be created between the treated and untreated surfaces dryness in oven at 1109C, the treated samples lost and the whole protection would collapse at once. only 2 percent in weight, while the untreated samples As far as penetration is concerned, ideas are of the same material completely disintegrated during still not very clear. Obviously complete impregnation the second cycle. would be most effective, but it is in most cases techni- The penetration of ethyl silicate in the walls is cally not achievable. Therefore a weak point always high and differs according to the porosity of the remains, represented by the connection between the surface, obtaining an irregular plane of contact with treated and untreated surfaces. The forces that keep the untreated part, and a gradient of the quantity of together these strata are even weaker than the adobe silica remaining on place. This is a great advantage itself, and if water can infiltrate behind the treatment, in the sense that no crust rigidly delimited from the its effect can be deleterious. Particularly so if the inner wall is formed, and therefore the chances of connection between the two parts is a flat surface. detachment are highly reduced. For all these reasons, those chemical treatments The disadvantages of ethyl silicate are that it which end in the formation of films of materials very does not possess "gluing" properties. If the wall is different from adobe, have been proved to be inef- already deteriorated in the form of pieces detached fective. from one another, the ethyl silicate treatment will not If the treated part is similar to the original keep them together, but simply consolidate each sepa- adobe, a penetration of one or two centimeters can rate piece. The same is true for those walls which be sufficient, provided that the surface of connection have a preformed and almost detached crust. If one is very irregular, to obtain a good keying effect. can afford to loose one or two cm of surface wall, The treatment should possibly be of easy ap- then the crust should be removed to obtain a solid plication, even by people not particularly trained, not surface before the treatment. ► f not, as in the case of harmful and not excessively expensive, given the possi- friezes or paintings, a combined technique can be ap- bility of application to large surfaces. plied, consisting cf consolidation with ethyl silicate Finally the treatment should be reversible, or followed by gluing together the pieces using injections at least, since complete reversibility in practical terms of polyvinyl acetate or similar products inside the wall is seldom achievable, should not prevent future treat- (12), (13). Preexisting cracks or little holes can be ments to be performed, of whatever nature they could used as a guide for the injections. The synthetic resin be. which, if sprayed on the surface would cause the

39 formation of a film easily detachable and whose chemi- Porous Building Materials — Material Science for Architectural cal composition would change in time due to the expo- Conservation. sure to light, performs instead very well inside the wall. ICCROM — (1982). 3. BROWN G. Ethyl silicate can be applied by spraying in a The X-Ray Identification and Crystal Structures of Clay Minerals. simple way. Mineralogical Society — London (1961). 4. TANNER AND JACKSON M.L. Soil Science Society Proceedings No. 12, (1947). 5. BRUNO A., CHIARI G., TROSSARELLI C., BULTINK G. Conclusions Contribution to the Study of Preservation of Mud-Brick Structures. Mesopotamia III-IV, (1968-69). In conclusion, I would like to stress a few points: 6. JCPDS — International Centre for Diffraction Data. For adobe characterization not always the more Powder Diffraction File SMH29. (Inorganic Phases). (1981). sophisticated analyses are the ones giving the more 7. MITCHELL J.K. valuable information. Fundamentals of Soil Behaviour. John Wiley & Sons, Inc., New York, (1976). Among the causes of alteration rain and possi- 8. TORRACA C., CHIARI G., GULLINI C. bly earthquakes are the most dangerous ones (and Report on Mud-Brick Preservation. also more obvious). Mesopotamia VII, (1972). Without a careful and constant maintenance 9. CLIFTON J.R. there is no hope of making an adobe structure to Preservation of Historic Adobe Structures — A Status Report. National Bureau of Standards — Technical Note 934, (1977). withstand weathering. 10. CLIFTON J.R. In case of archaeological excavations the pres- Mechanical Properties of Adobe. ervation intervention should be performed as soon as National Bureau of Standards — Technical Note 996, (1979 ). possible, the ideal case being the conservator working 11. ROSSI MANARESI R., GHIARI G. Effectiveness of Conservation Treatments of a Volcanic Tuff very together with the archaeologist during the campaign. Similar to Adobe: Surface treatments, although in some special con- III International Symposium on Mud Brick (adobe) preservation. ditions efficient, cannot up to now, and probably never Ankara (1980). will, garantee the safeguard of adobe structures. 12. CHIARI G. Conservation de monumentos arqueologicos en adobe. UNESCO mission report — UNDP/RLA/72/047, (1975). 13. CHIARI G. References Treatment of Adobe Friezes in Peru. 111 International Symposium on Mud Brick (adobe) preservation, 1. CLIFTON J.R., BROWN P.W., ROBBINS C.R. Ankara (1980). Methods. for Characterizing Adobe Bulkling Materials. —A long list of references can be found in the quoted (9) National Bureau of Standards — Technical Note 977, (1978). Technical Note 934 by J. Clifton, as well as in the other refer- 2. TORRACA G. enced papers.

40 Notes on the Manufacture of Adobe Blocks for the Restoration of Earthen Architecture

Alejandro Alva Balderrama Jeanne Marie Teutonic°

1.0 Introduction and selection of the soil, continue with its preparation and molding, and conclude with a drying period. There The restoration of earthen architecture frequent- are many manuals and reports which describe these 1y requires the completion of existing structural ele- operations. Not all of them include every necessary ments with adobe blocks having similar characteristics. operation, nor explain in detail the rationales on which This paper summarizes, for training purposes, various aspects of the process are based. Sections 3.0 the basic specifications for the manufacture of adobe to 7.0 of this paper attempt to summarize the basic blocks and illustrates the most important aspects of the phases of the manufacture process and to examine some process. of the arguments which justify the procedures frequent- ly recommended. To do this, we have reviewed most of the important manuals and have organized a number 2.0 Distinct phases in the manufacture of figures which illustrate the text and a series of of adobe blocks photographs which show the most important phases of such work in situ. The latter represents a practical The manufacture of adobe requires a series of experience requiring the manufacture of traditional diverse operations that begin with the identification adobe for the restoration of monuments.

41 CLASIFICACION GRANULOMETRICA 3.0 Identification and selection of soil CLASSIFICATION BY PARTICLE SIZE (Based on BS 1377: 1975)

Test Particle size (mtn.) Designation procedure 3.1 The nature of soil Measurement 200 BOULDERS of separate 200 pieces COBBLES From a geotectonic point of view, 'soil' is defined 60 Coarse as the unconsolidated accumulation of solid particles 20 Sieve Medium GRAVEL produced by the physical and chemical disintegration 6 analysis Fine of rocks, and which may or may not contain organic 2 Coarse matter (1). Another definition says: any naturally oc- 0.6 Medium SAND curring deposit forming the outer part of the earth's 0.2 Fine crust, consisting of an assemblage of discrete particles 0.06 Coarse (usually mineral, sometimes with organic matter) that 0.02 Sedimentation Medium SILT can be separated by gentle mechanical means, together 0.006 analysis Fine with variable amounts of water and gas (usually 0.002 air) (2). and less CLAY The variety of existing has necessitated the development of empirical methods for their classifi- HEAD

cation and study regarding: 0.002 0.06 2 60 nun. —identification; colloids fine medium I coarse —physical and mechanical characteristics; CLAY SILT SAND GRAVEL COBBLES —behaviour as construction materials; —modification if necessary. particle size 1 5 75 425 um 2.00 4.75 76.2 mm. sieve designation N"200 No 40 NI" 10 N, 4 3 inch. Similarly, the various forms and dimensions of

the solid particles which constitute soils has necessi- (a) U.S.A. ASTM D422 tated their analysis and classification based on particle

size characteristics. Through this type of analysis, soils fine' medium 1 coarse fine' medium coarse fine' medium coarse . . - can be divided, based on their dominant particle size, CLAY SILT SAND GRAVEL BLES BOULDERS into six arbitrary categories which are: particle size 2 6 20 60 200 600 um. 6 20 60 600 nom. — sand —boulders —cobbles —silt (b) Great Britain BS1377: 1975 —gravel —clay Soils in natural deposits are composed of dif- In general the solid particles which are recog- ferent proportions of the designated solid particles; nized and analyzed as 'soils' include the last four these, similarly, possess diverse physical, chemical, and categories: gravel, sand, silt and clay. mechanical characteristics which are not always suitable The two charts (3) which follow represent: in a good soil for the manufacture of adobe blocks. — the classification of soils by particle size with respect It is, therefore, important to define the function of to their designation and the procedure for separating each solid particle in the whole of the adobe soil mix. them by size and, To clay is attributed the property of cohesion —the comparison of two systems of classification based in the soil composition, or better, that of 'binder' of the on particle size characteristics; (U.S.A.) ASTM D422 mix. Some of the processes related to this property and (GBR) BS 1377: 1975. of clay are discussed in point 5.2 of this paper.

42 The function of silt is not so well defined. Tests possible to produce an adobe block having even a carried out on solid particles of silt characterize it as a minimally acceptable degree of stability for construc- material of poor plasticity, of marked dilatancy [1], of tion purposes. It is, therefore, fundamental to define low cohesion, and that disintegrates easily on contact the characteristics of a good adobe soil. with water. Contrary to these conclusions, however, which suggest that silt is not suitable as a dominant 3.2.1. The particle size composition of the soil component of an adequate adobe soil, certain re- searchers (5) also characterize silt as a 'binder' ma- In this regard, the existing literature presents terial in the mix, though clearly to a lesser extent certain differences. Following are several examples of than clay. Moreover, it seems to be accepted that an proposed specifications for the composition of an adobe adobe soil should contain equal quantities of clay and soil. These in turn are followed by the results of silt as binder materials in the mix (6). Taking into tests carried out on adobe samples obtained from monu- account these last considerations, we think that the ments or, simply, from structures built in the past: precise function of silt in the soil mix should be better —The soil of CRAterre (7) ; extracted from a quarry defined. containing no coarse stones roots nor organic earth: Sand, another component of adobe soil is formed of an assemblage of solid particles or fine grains produced by the disintegration of various rocks, princi- + sand 55 — 75% pally quartz. This material functions as stabilizer of the + silt 10 — 28% clay and silt in the adobe soil mix. It is, thus, the sand clay 15 — 18% in the mix which improves the behaviour of the clay, + organic material less than 3% especially in the early phases of its preparation. It is + Alkaline salts maximum 0.2% the clay which is responsible for fractures and bulging, —The soil of Proyecto PER 71/539 (8): produced by the processes of expansion (through the 60 — 68% absorption of water) and unequal shrinkage (by dehy- + sand 10 — 28% dration) of the block during drying. Sand functions as + silt + clay 15 — 18% a filler which mitigates these reactive processes. This problem, as well as the occasional presence of residues + organic material & salts : maximum 0.3% (organic material, gravel, and others) are discussed —The soil of EBS (9): later in the text. + sand 50% + silt & clay not less than 50% 3.2 The evaluation of the soil + organic material & salts not specified Due to the specific characteristics of each solid —The soil of Adobe Codes of Arizona, California and particle, the proportion in which they are found in a New Mexico (10): certain soil will influence the behaviour of that soil + sand not specified should it be used for the manufacture of adobe. Expe- + silt minimum 25% rience demonstrates, in fact, that it is possible to pro- + clay in sufficient quantity duce 'better' adobes with certain soils than with others; for the cohesion of or, in the extreme case, that with certain soils it is not the mix + organic material net specified + soluble salts 0.2 — 2% [1] Property of volume increase under loading (ISRM ). The —The soil of NBS (11): expansion of cohesionless soils when subject to shearing defor- mation. + gravel little or none

43 + sand 60 — 80% —The soil of 'Tell'Umar' (20): + silt & clay 20 — 400/o + gravel & sand 32% + organic material not specified + silt 49 % + soluble salts not specified + clay & colloids 19% + organic material —The soil of 'Tumacticori' (12): [2] + soluble salts + gravel 2% [3] + sand 24% + silt 26 % To these preceding examples could be added + clay 460/0 many others more or less representative of diverse + organic material not specified soil mixes for adobe. Those presented will suffice, + soluble salts 0.17 — 8.78% (13) however, to attempt some generalizations. A first consideration, often mentioned in recom- —The soil of 'Escalante' (14): mendations for the proportions of particles in soils, is + gravel the preference for soils without organic material. The + sand 18% rationales for such recommendations are discussed in + silt 55% point 4.3 of this paper. For the present, it will suffice + clay 27% to say that, according to traditional practice, adobe + organic material not specified soils should not contain organic materials or extraneous + soluble salts 1.6% (15) residues. — The soil of `Satnarra' (16): Secondly, due to the well known destructive +' gravel & sand 62 % effects of efflorescence, the content of soluble salts + silt 12% should be extremely low or non-existent. Maximum ac- + clay & colloids 26 ceptable percentages range from 0.3 to 3%. Another ex- + organic material [2] tremely important consideration in relation to the pres- + soluble salts [3] ence of soluble salts concerns the layering structure of the clay particles. Some treatises dealing with the struc- —The soil of 'Ur' (17): ture of soil state that clay sedimented in salt water 1 7% gravel & sand solutions tends to develop a highly flocculated structure silt 68% in comparison with those particles which sediment in clay & colloids 15% fresh water. Since a highly flocculated structure gen- organic material [2] erates large voids, the mix will have a low density that, soluble salts [3] ultimately, weakens the strength of the block. —The soil of 'Choche' [4] (18): Thirdly, there is a preference for soils which do gravel & sand 7% not contain gravels, fundamentally due to the un- silt 59% suitable formal and dimensional characteristics of these clay & colloids 34% particles as aggregates. organic material [2] soluble salts [3] (19): —The soil of 'Agar Our [2] The lack of organic material in some of the analysed samples + gravel & sand 14% is attributed to its decomposition and to its reaction with the + silt 58% mineral components of the soil. + clay & colloids 28% [3] The presence of soluble salts appeared to be considerable; + organic material [2] however, the test results were considered inconclusive. + soluble salts [3] [4] Sample N9 5. One of three.

44 A schematic representation of clay and silt particles combined u=ii Clay particle in a flocculated structure in an undisturbed salt water deposit and, alternately, in an undisturbed fresh water deposit: at Silt particle

Eitt9019:10 Clay particle Silt particle

Undisturbed salt water deposit Attraction = repulsion Water in low-energy (I)) (c) Final structure at end of thixotropic hardening structure

(a) Aged strength Flocculated-type structure (edge to face contact) Undisturbed fresh water deposit

br) Remolding A schematic representation of thixotropic [5] structural change in a soil of fine particle size: Remolded strength Shaded area represents absorbed water layer Time (d)

Finally, as regards the proportion of sand with respect to that of clay/silt, it is difficult to make gener- alizations. The varied physical and mineralogical char- acteristics of clays diversely affect the behaviour of Attraction >> repulsion Water in high-energy adobe soil mixes. It is, therefore necessary to carry (a) Structure immediately after out a series of tests in order to determine approximate remolding or compaction structure proportions for the adobe soil mix.

3.2.2. Tests for evaluating the characteristics of adobe soil The necessity for precise characterization of soil for adobe manufacture has led to the development of various procedures for the better evaluation of physi- cal, minerological, and mechanical properties. Most of Attraction > repulsion these tests consist of empirical methods derived from (b) Structure after thixotropic hardening partially complete disciplines such as Geotechnics, Physics, and/or Soil Mechanics. Since it is not always possible, however, to (5] Thixotropy: Phenomenon by which certain gels pass to the count on the aid of a laboratory or, even, of the liquid state when agitated and are reconstituted when at rest. necessary equipment/instrumentation for the required

45 tests, some of them have been simplified to provide —sticky limit; approximate data on the characteristics of the subject —linear shrinkage; soils. — puddle characteristics; Diverse publications, reports, and manuals con- —swelling capacity; tain detailed descriptions of all these tests. It is, —density; therefore, unnecessary to explain them. For the pur- —specific gravity; poses of this paper, we will limit ourselves to an indi- —particle size distribution; cation of the most important references and to some —indices of acidity and alkalinity (pH); brief commentary on the efficiency of the proposed —content of sulfates; methods. —organic content; —content of carbonates; 3.2.2.1. The series of NBS Technical Notes: 934 (21), —content of chlorides; and 977 (22), and 996 (23) —compaction tests. This series, especially the second and third notes, 3.2.2.3 Tests proposed in manuals for the construction proposes and describes necessary procedures for the of adobe dwellings: AID (26), EBS (27), CRY RZAI characterization of the most important properties of PREVI (28), CRAterre (29), Adobe Craft (30), and adobe soil, these are, in the estimation of the authors, others (31) the following: All these manuals contain simplified tests de- —colour determination; rived from laboratory procedures; they provide ap- —determination of soluble salt content; proximate methods for the evaluation in situ of soil —determination of pH; characteristics. Among those tests most commonly ex- —particle size distribution; plained are the following: —determination of liquid limit; —determination of plastic limit; —the 'mud roll' test (for approximation of the correct — X-Ray Diffractometry; proportions of clay/sand); — microscopy; — the 'groove' test (verification of the water content —determination of compressive strength; of the mix); —determination of flexural strength; —the 'bottle' test (for the approximate estimation of —analysis of creep [6]. particle size characteristics); —tests for strength and quality control (with the 3.2.2.2. The Manual of Soil Laboratory Testing (25) weight of a person, of adobe blocks, or with simple Though not referring specifically to adobe, this levers); tests (verification of the permeability of manual contains valuable information regarding neces- —immersion sary equipment, theoretical foundations and detailed stabilized adobe); diverse observations on the deformations of the procedures for all tests concerning the correct iden- — tification and characterization of soils. The text specifi- mixes, etc. cally refers to the following tests: A general observation concerning the efficiency of all these tests should be made here. It must be —moisture content; remembered that, due to the mineralogical character- —Atterberg limits (liquid, plastic, shrinkage); istics of each type of soil, such tests could generate diverse results with samples equally suited to the man- [6] Slow movement of rock debris or soil usually imperceptible ufacture of adobe. Therefore, whenever possible, the except to observations of long duration. Time — dependent strain or deformation, for example, continuing strain with sustained validity of these models should be verified with precise stress (24). laboratory tests.

46 4.0 Preparation of the soil In this regard, it is interesting to note that the earth one finds at the top of rolling hills or ridges is 4.1 Selection of quarries and yards more likely to contain clays, while that at the bottom will contain largely . The needed mixture of sand 4.1.1. The quarry and clay could be found somewhere in between (34). The location of the adobe quarry, therefore, will As discussed in the previous section, only cer- be determined largely by the availability of an ade- tain soils are suitable for the making of adobe blocks. quate supply of appropriate soil. Obviously, for reasons These contain established proportions of clay, silt, and of efficiency and cost, the quarry should be as close sand and a low content of organic material. In ad- dition, they must not be highly alkaline nor high in as possible to the construction site. soluble salt content [7]. In general, therefore, topsoil — which contains 4.1.2. Extraction a high proportion of vegetative material— is not suita- ble for adobe construction. It is rather the Extraction of the soil can be accomplished by levels of sand and clay which, when mixed together, machinery or through hand labor (men with picks and will provide the basis for a good adobe block (33). shovels). If dug by machinery, however, the soil will be in large clods and will have to be broken up before mixing. Manually dug soil, on the other hand, will require little further breakdown. A schematic representation of a soil profile of the EBS manual Often, it will be necessary to extract two dif- ferent soils which will later be mixed to form the most desirable adobe material. If this is the case, the diverse soils should be brought to the building site and kept Surface soil in separate piles until ready for blending. Some manuals suggest an extraction method which allows mixing of soils in the quarry (35). The builder first removes the layer of top soil. He then digs down the sides of the hole through both layers making his - Subsoil building mixture as he goes along by adjusting the quantities of each soil type he digs. Carefully done, such an extraction method could prevent extensive Deconiposed rock blending on the construction site. It is estimated that the volume of earth dug must W.C7•'7"grZ1-74.74;j:7A z"Ze'r ofZe'r be 30% greater than the total volume of needed bricks .47 4.27 g_ Fresh rock 4.. 2'vc," (36). MIDDLETON 4.1.3. The construction yard The construction yard must be large enough to accommodate all the procedures involved in the making [7] Alkalinity and soluble salt content are especially problematic of an adobe block — from screening and blending of in arid or semi-arid regions. In general, for highly durable the soil through molding, drying and stacking the adobe blocks, the salt content of the soil should not exceed 0.2% by weight of the soil. Since salt cannot easily be removed adobe blocks. It must be provided with an abundant after the soil is quarried, tests for salt content should be done supply of clear water and some type of protective prior to extraction (32)• structures to safeguard the blocks from rain.

47 It should be stressed that the organization of Adobe blocks made with such material would have the adobe construction yard is critical to the success greatly weakened compressive strength. It is essential, of any project. Attention should be given to the loca- therefore, to eliminate large stones and gravel from tion and proximity of various functions in the yard in the quarried soil before beginning the blending process. order to assure the most efficient use of space and Organic materials are removed for other reasons. time. Firstly, organic soils (those high in organic matter) tend to be rather spongy. They are, thus, highly compressible and exhibit poor load-bearing properties. Residue elimination 4.2 Secondly, and perhaps more critically, organic Once the quarried soil has been brought to the materials decay through the action of bacteria, re- construction yard, the first step in the preparation leasing acid into the soil. This decomposition renders process is to remove all undesirable residue. These the material unstable, increases its porosity (due to include large stones, gravel and all organic material the creation of a more highly flocculent clay struc- such as decaying leaves, wood and roots. Domestic ture), and weakens its compressive strength (38) (39). trash and other waste products such as fly ash must Such conclusions about the undesirability of or- also be eliminated. The rationale for such a prepara- ganic matter in soil for adobe blocks may initially seem tory step —essential for the production of durable to contradict the traditional use of fibrous organic blocks— can be explained as follows. materials such as straw or camel hair in mud-brick In terms of coarse material such as stones and manufacture. It has been found that such fibres have gravel, the rationale for elimination is related to the a strengthening effect on adobe which persists even physical structure of clay. Clay particles are flat, hex- after the fibres have disappeared probably due to agonal shapes, hydrophilic in nature. Characteristically, some reactions between clay minerals and materials when lubricated with water, these plate-like shapes extracted from the fibres or produced in their decom- stack in layers creating an overlapping structure (sim- position (40) (41). ilar to brick masonry). When subject to compressive There is a difference, however, between such forces, they will not break apart but rather slide past purposeful addition of organic fibre and the failure to one another. The closer and more uniform the stack- remove what can be termed organic refuse (dead ing (the denser the mass), the better will be the leaves, wood, roots, etc.). While the former may have mechanical properties of the clay and, eventually, of beneficial effects on adobe blocks, the latter are gene- the adobe block [8]. rally agreed to substantially weaken the final product. Stones and gravel, if allowed to remain in the soil, disrupt this stacking structure. They cause some Screening of the flat hexagonal clay particles to stand on end, 4.3 creating weakness in the clay which allow it to rupture. Once all undersirable residue has been removed, the soil is ready for screening or sifting. This can be accomplished with several types of simple equipment. The most typical screen is simply a rectangular wooden [8J These are some situations in which it is desirable to have a certain percentage of non-clay particles in the mix. In making frame (about 2.5' x 5') on which is mounted a 0.25" — ceramic pots (especially tall ones), for example, the presence of 0.5" (6-12 mm.) mesh (hardware cloth or a similar• less regular, more rounded non-clay particles provides some material). One end of the screen is propped up on abrasion which allows, the clay wall to stand up (37). In this two legs; the soil is simply dropped through the screen instance, the com•se particles prevent the clay from 'slipping' with shovels (42). Anything which does not pass is or deforming in the vertical plane. For the fabrication of adobe blocks, however, where the clay discarded or crushed again and rescreened. should have maximum strength in the horizontal plane, an When two different soils are to be blended, uninterrupted stacking structure is desirable. they should be screened separately and kept in sepa-

48 rate piles. The proper proportions of each soil can result in a block of poor strength which will shrink then be gauged at the time of mixing. considerably upon drying. Too little water will result in a soil of inadequate plasticity which will crumble when molded. Though it is impossible to specify in quantifiable terms the 'optimum' percentage of mixing water for every adobe soil, some general statements are possible. The desirable amount of mixing water is related to the liquid and plastic limits of the soil. The liquid limit (LL) is defined as the moisture content (in per- cent by weight) at which soil passes from the plastic to the liquid state. The plastic limit (PL) is the moisture content at which the soil passes from the plastic state to the solid state — that is, the point at which it becomes too dry to be in a plastic condition and crumbles when worked. The plasticity index of a soil is defined as the liquid limit minus the plastic limit. To- gether these three factors provide some information concerning the dimensional response of clay to moisture. Most simply, different clays exhibit different li- quid and plastic limits (Clifton 977, Table p. 25). Thus, the type of clay will influence the amount of mixing water required. In addition, liquid and plastic limits WO LFSKI L L are significantly affected by several other factors such as the presence of organic matter and the type and Using this type of manual screening, it is esti- amounts of soluble salts (45). mated that a man can screen 4 m3 of earth per day As regards the plasticity index, it has been found (43) [9]. that higher plasticity indices are accompanied by larger expansions upon wetting and larger shrinkages upon drying. According to Clifton, therefore, the closer that adobes match in their plasticity indices, the more 5.0 Preparation of the mix compatible will be their dimensional responses to mois- ture (46). 5.1 The optimum amount of mixing water The works of various other researchers (47) The amount of mixing water is of critical impor- have established additional information concerning the tance in making adobe blocks. Too much water will proper amount of water needed for making adobe blocks. Schwalen, for example, found that the proper amount of mixing water depends on the proportions of clay and silt in the soil. He also found that the [9] More complicated sifters have been developed which are said magnitude of shrinkage varies with clay content, type to be more efficient. A particularly interesting example is the of clay, and amount of mixing water. In this regard, power-driven barrel sifter described in Adobe Craft (44) con- sisting of a plastic garbage container which rotates on roller skate Webb found that drying shrinkage is not a linear . The sifter is belt driven by a pulley powered by a function of the amount of mixing water; rather, higher heavy duty hand drill motor. water content shows considerably increased shrinkage.

49 Some researchers (Fenton, Webb) suggested that it is The so-called 'seasoning' of the blended mix possible to ascertain the optimum amount of mixing permits a slow penetration of water between the clay water for each adobe soil, i.e. that which gives the particles which, consequently, divides them into a larger highest strength and density to the block. In their own number of finer particles. Simultaneously, the weight work, the NBS (48) discovered that the optimum of the 'seasoning' mix causes a slow compression of all amount of water was generally somewhat less than the the particles. The 'souring' (or 'seasoning') also im- liquid limit. This they attributed to the large percent- proves the plasticity of the mix, making it more worka- age of particles in the adobe soil larger than 425 mm. ble, and contributes to the development of its strength which absorb much less water than clay size particles. characteristics. From the above discussion, it is clear that no simple guidelines can be given for the optimum amount of mixing water in the making of adobe blocks. Most field manuals, therefore, provide the builder with either 5.3 Aggregates / stabilizers a very general percentage range for the amount of Prior to molding of the block, one or more di- water (from 15 — 30% depending on the manual) or verse materials can be added to the blended mix. with some very basic empirical tests. It is suggested, Among those traditionally used are: bark, wood for example, that the soil is at the correct moisture shavings, straw, hemp, fly ash, sap, coconut oil, tannic content for molding adobe blocks when it no longer acid, urine, dung, molasses, rotted plantain leaves, etc. adheres to metal utensils (49) (50). Another simple (52). test to determine proper consistency is to draw a stick Opinions on the efficiency of these aggregates through the mix surface; if a smooth wet indentation and other traditional 'stabilizers' are diverse and often remains, the soil is at the proper consistency. In the contradictory. Some assert the effectiveness of certain final analysis, however, it is only experience which will aggregates for specific cases. Others report that, based enable the builder to judge the optimum water content. on laboratory tests, there is no considerable im- provement in the properties of blocks made with some of 5.2 Blending of the soil the mentioned aggregates as compared to those without aggregates. One of the most important phases in the prepa- There are, however, at least two hypotheses re- ration of the mix consists of adding the necessary garding the function of the mentioned stabilizers. The quantity of water to the selected soil, followed by first suggests (in the case of fibrous aggregates) a blending and turning to achieve a plastic consistency mechanical function of the aggregate during the de- [10]. Through this process, a homogeneous and plastic hydration (drying) of the block. The fibres compensate mix is obtained. Such characteristics ensure workability for the stresses induced by the shrinkage of the clay. and strength. The homogenization of the mix causes thus avoiding excessive or unequal shrinkage and frac- the regular distribution of the solid particles and the tures of the block. The second hypothesis suggests added water in the total mass. This contributes to the organic activity which promotes the multiplication of necessary friction between the clay and non-clay par- bacteria and the formation of amino acids (thus modi- ticles and to the development of cohesive properties, fying the acidity index). This process creates better the latter resulting from the structure formed by the conditions for the flocculation of the finest particles fine particles and the water. Both factors are critical of the soil (53). to the consistency and ultimate strength of the mix. At the worksite, the organic aggregates should be proportionately mixed with the blended soil. Some manuals recommend mixing the aggregate with the soil [10] Blending time is estimated to be at least one day, followed for at least one day. Following this, the blended mass by a period of 'seasoning' of at least one night (51). must 'season' for at least one night.

50 6.0 The preparation of the block

6.1 Forms or molds, characteristics of the block, quality and efficiency The geometric form of an adobe block is, gene- PARRY rally, a parallelepiped [I I]. The dimensions of this solid vary according to local usage, to construction specifi- cations, to the need for a precisely dimensioned block for restoration or the completion of a wall, to the ti capability of the worker, etc. An inventory included in a recently published manual (54) contains at least 33 different combinations of mold dimensions. Each mold has different characteristics with regard to the number of blocks which can be fabricated at one time, the type of handle, material, and base. Some manuals group molds into two major categories: those having a base (or bottom) and those without bases (57). The method and handling of the mold will differ depending on which type is used. Thus, with a baseless mold, the worker forms the block on the sur- face of the yard where it will rest during drying. With a mold having a base, the worker remains standing and forms the block on a table (or pedestal) on which the mold rests. According to studies made by Programa PARRY COBE (58), the first method is more efficient, but results in a less compacted block and greater fatigue Traditionally, molds are made of wood (having on the part of the worker. With the second method, sufficient strength and section to withstand continuous efficiency is lower but compaction is improved and use and handling). Some manuals (60) suggest covering worker fatigue diminished. Whichever mold is chosen the wood with regular and impermeable surface mate- (with or without base), maximum attention must be paid rials (vinyl, polyethylene, latex, formica, fiberglass and to deformations of the block resulting from handling of other synthetic materials). The use of metallic revet- the mold. This is especially critical in the case of the ment (aluminum, sheet steel) is also mentioned. mold with base where it is necessary to turn the mold In our opinion, the traditionally wooden mold 1809 in order to deposit the block on the yard sur- (of a single block) is not problematic. If adequately face. constructed and maintained, it will give excellent re- The following figures show several possible de- sults. Moreover, with a wooden mold, it is possible to formations due to the type of mold and its handling control the consistency of each block immediately after (59). it is removed from the mold. It is recommended that wooden molds be soaked for the entire night preceding the molding day. It is also important to adequately lubricate the molds before molding and whenever neces- [11] Certain construction systems use blocks molded by hand sary during the molding process. In this regard, some creating geometric forms which are irregular or simply different manuals recommend wetting and oiling the mold. Others from the parallelepiped (55) (56). suggest wetting the mold and then coating the internal

51 surfaces with fine sand or, simply, keeping the mold 7.0 Curing of the adobe block wet during the entire molding process. In our opinion, the best system of lubrication (according to the type of soil used) can be decided on the basis of tests 7.1 Drying made during the molding process. It will not be diffi- Proper curing of the adobe block demands slow, cult to modify any of the cited recommendations should even drying. Excessively rapid drying will lead to they prove problematic. cracking of the block; damp or cold conditions will prolong the drying process. Thus, to ensure a good 6.2 Molding cure, the environment of the drying blocks must be carefully controlled. In excessively hot climates, it may In molding the block, various operations are be necessary to provide some type of protective cover- distinguished. The first consists of pouring the prepared ing to keep the bricks in shadow for the first few days material into the mold, being careful to fill it complete- of cure. Some manuals also recommend occasional ly and to compact the mix. Small changes in this spraying of the bricks or covering them with straw, operation result, for example, from the type of mold sand, shade cloth, etc. (63). Similarly, if rainfall is a used (with or without base), etc. Section 6.1 includes possibility, some type of protection must be provided. some considerations on this point. In any case, the In general, the drying can be described as follows. basis of this first operation is pouring the material and After removal of the molds, the blocks are left in their compacting it in the mold. original position for several days (2-5 depending on Secondly, it is necessary to 'level' or 'trim' the the manual) until firm enough to be handled. They excess material from the upper surface of the mix in are then turned on edge to expose the bottom surface the mold. A wooden stick or 'rule' can be used to and to allow more equal drying. At this time, any smooth this exposed surface of the block. The removed excess material clinging to the block can be removed material is added to the mix for the following block. with a small stick. In this position, the blocks are left Thirdly, if a better finish of the exposed block to dry for another three weeks at which time curing is surface is desired, a final levelling can be accomplished considered complete. with a trowel or similar type of mason's . In some There are, of course, variations on this general cases, this operation is carried out while throwing water process. Some manuals recommend a second turning on the exposed surface. on end after 15 days (64) to again change the venti- Finally, the mold is emptied, lifting it (mold lation of the block. This, of course, is only possible if without base) or turning it (mold with base) so as to the block has dimensional stability on its short side. place the molded block on the yard surface [121. Other authors also suggest that it is possible to stack Once the mold is emptied, the consistency of the the blocks allowing adequate ventilation after only two block can be checked, noting possible deformations or weeks of drying (65) (66) (67) (68). fractures. Some manuals suggest adjusting the quantity The cure is completed in the stacked position. of water in the mix if such problems are evident (61) In the opinion of the authors of this paper, however, (62). It is also important to check that the mold is such premature stacking is not advisable since it places adequately lubricated, according to the specifications stresses on partially cured blocks which could lead to mentioned in section 6.1. These problems and consider- cracking or deformation. ations are well illustrated in the previously cited manuals. 7.2 Piling

[12] Some manuals recommend covering the surface of the yard When the blocks are completely cured (about with a layer of fine sand to prevent the fresh blocks from four weeks from the removal of the molds), they are sticking to the ground during drying. ready to be piled for use. According to traditional

52 practice, the blocks are stacked against a central pier of Arizona, California and New Mexico. Adobe News, Inc., Al- formed of face-bedded adobe. This method is spatially buquerque, New Mexico, 1982, pp. 8, 10, 14, 55. 11. CLIFTON, James R. BROWN, Paul W. - ROBBINS, Carl R. efficient and allows the worker to handle the block in Methods for Characterizing Adobe Building Materials. In: NBS its strongest position. Technical Note 977, Washington, DC, USA, Department of Com- 7.2.1. A merce/National Bureau of Standards, 1978, p. 12. note on curing 12. CLIFTON, James R. - DAVIES, Frankie. Mechanical Proper- It is essential that adobe blocks be completely ties of Adobe. In: NBS Technical Note 996, Washington, DC, USA, Department of Commerce/National Bureau of Standards, cured before use. Though some builders suggest laying 1979, p. 3. partially cured blocks, this practice is never recom- 13. BROWN, Paul W. - ROBBINS, Carl R. - CLIFTON, James R. mended. Only a completely cured block is thoroughly Factors Affecting the Durability of Adobe Structures. Washington, flocculated, has attained an acceptable moisture con- DC, USA, Department of Commerce/National Bureau of Standards, tent [13] (and thus will not shrink further after being 1978, p. 15. laid) and has achieved maximum compressive strength. 14. CLIFTON, James R. - DAVIES, Carl R. Op. cit., p. 3. 15. BROWN, Paul W. - ROBBINS, Carl R., CLIFTON, James R. The quality of cured blocks, in fact, should be checked Op. cit., p. 4. through established tests before they are considered 16. TORRACA, G. - CHIARI, G. - CULLINI, G. Report on Mud suitable for construction. Though these control tests Brick Preservation. In: Mesopotamia VII, Torino, G. Giappechelli are outside of the scope of this paper, they are Editore, 1972, p. 263. clearly described in the cited manuals. 17. TORRACA, G. et alii. Ibid., p. 263. 18. Id., Ibid., p. 263. 19. Id., Ibid., p. 263. References 20. Id., Ibid., p. 263. 21. CLIFTON, James R. Op. cit. 1. ASTM. Standard Definitions of Terms and Symbols Relating 22. CLIFTON, James R. - BROWN, Paul W. - ROBBINS, Carl to Soil and Rock Mechanics. In: 1979 Annual Book of ASTM R. Op. cit. Standards, Part 19 Soil and Rock; Building Stones; Yeats, Phila- 23. CLIFTON, James R. - DAVIES, Frankie. Op. cit. delphia, American Society for Testing and Materials, 1979, p. 187. 24. ASTM. Op. cit., p. 172. 2. HEAD, K.H. Manual of Soil Laboratory Testing, Volume I: Soil 25. HEAD, K.H. Op. cit. Classification and Compaction Tests. Plymouth, Pentech Press, 26. WOLFSKILL, Lyle A. - DUNLOP, Wagne A. - CALLAWAY, 1980, p. 3. Bob M. Handbook for Building Homes of Earth. Washington, 3. Id., Ibid., p. 146 DC, Agency for International Development, s.d. 4. ASTM. Op. cit., p. 173. 27. MIDDLETON, C.F. Op. cit. 5. CLIFTON, James R. Preservation of Historic Adobe Stnictures, 28. COMISION DE RECONSTRUCCION Y REHABILITACION A Status Report. In: NBS Technical Note 934, Washington, DC, DE LA ZONA AFECTADA (CRYRZA ) - PROYECTO EXPE- Department of Commerce/National Bureau of Standards, 1977. p. RIMENTAL DE VIVIENDA (PREVI). Manual para la Construe- 4. ruin de Viviendas con Adobe. In: Adobe News, N° 12, 13, 14, 6. Id., Ibid., p. 4. y 15, Albuquerque, .New Mexico, Adobe News Inc., 1976-1977. 7. CRAterre. Construire en terre. Paris, Alternative et Pa- 29. CRAterre. Op. cit. ralleles, 1979, p. 111. 30. SCHULTZ, Karl V. Adobe Craft, Illustrated Manual. Castro 8. DE SUTTER E., Patrick. Informe sobre Pruebas de Adobe Valley, CA., Adobe-Craft, 1972. Aplicado a la Restauracion de Monumentos. Cusco, author, 1978, 31. PROGRAMA COBE. CONVENIO MVC-AID. Mejores Vivien- p. 6. des de Adobe. Lima, Ministerio de Vivienda y ConstrucciOn/Ofi- 9. MIDDLETON, G.F. Earth-Wall Construction. In: EBS Bulletin cina de InvestigaciOn y NormalizaciOn, 1978. 5, Department of Transport and Construction-Experimental Building 32. SCHULTZ, Karl V. Op. cit., p. 3. Station, Canberra, Australian Government Publishing Service, 1982, 33. MIDDLETON, C.F. Op. cit., pp. 7-8. p. 11. 34. WOLFSKILL, Lyle A. et alii., Op. cit., p. 11. 10. ADOBE NEWS, INC. Adobe Codes, A Guide to the Codes 35. Id., Ibid., p. 74. 36. CRAterre. Op. cit., p. 112. 37. HAMER, Frank - HAMER, Janet Clays. London, Pitman- [13] The equilibrium moisture contents of sundried adobe brick Watson Guptill, 1978, pp. 27-28. vary with their clay content but usually are in the range of 38. CRAterre. Op. cit., p. 111. 1-3% (69). 39. SCHULTZ, Karl V. Op. cit., p. 3.

53 40. HAMER, Frank - HAMER, Janet. Op. cit., p. 32. 58. PROGRAMA COBE. CONVENIO MVC-AID. Mejores Vivien- 41. TORRACA, G. et alii., Op. cit., p. 263. das de Adobe. Lima, Ministerio de Vivienda y Construcción/Ofi- 42. WOLFSKILL, Lyle A. et alii., Op. cit., p. 77. cina de Investigación y Normalización, 1978, p. 3. 43. CRAterre. Op. cit., p. 112. 59. PARRY, J.P.M. Brickmaking in Developing Countries. Watford, 44. CLIFTON, James R. - BROWN, Paul W. - ROBBINS, Carl Building Research Establishment/Building Research Station, 1979, R. Id., Ibid., p. 25. pp. 11, 79, 82. 45. Id., Ibid., p. 26. 60. SCHULTZ, Karl V. Op. cit., p. 7. 46. Id., Ibid., p. 26. 61. PROGRAMA COBE. CONVENIO MVC-IAS. El Adobe Esta- 47. CLIFTON, James R. Op. cit., pp. 4-5. bilizado. Lima, Ministerio de Vivienda y Construcción, Oficina de 48. CLIFTON, James R. - DAVIES, Frankie. Op. cit., p. 2. Investigación y Normalización, 1978, p. 9. 49. MIDDLETON, G.F. Op. cit, p. 57. 62. COMISION DE RECONSTRUCCION Y REHABILITACION 50. SCHULTZ, Karl V. Op. cit., p. 5. DE LA ZONA AFECTADA (CRYRZA ) - PROYECTO EXPERI- 51. DE SUTTER, Patrick. Ensayo de Manual de Materiales y MENTAL DE VIVIENDA (PREVI ). Op. cit. Métodos Con.;tructivos para la Restauración en la Región Andina. 63. SCHULTZ, Karl V. Op. cit., p. 8. Cusco, author, 1978, p. 20. 64. DE SUTTER, Patrick. Ensayo de Manual de Materiales y 52. WOLFSKILL, Lyle A. et alii., Op. cit., pp. 45-49. Métodos Constructivos para la Restauración en la Región Andina. 53. HAMER, Frank - HAMER, Janet. Op. cit., pp. 31-33. Cusco, author, 1978, p. 20. 54. CRAterre. Op. cit., pp. 113-118 65. SCHULTZ, Karl V. Op. cit., p. 8. 55. Id., Ibid., p. 107. 66. MIDDLETON, C.F. Op. cit., pp. 59-63. 58. SAMANIEGO ROMAN, Lorenzo. Catálogo de Exposiciones 67. MIDDLETON, C.F. Build Your House of Earth. Milsons de Adobes Pre-hispánicos de los Valles de Sechín, Casma, Nepe- Point NSW, Compendium/Second Back Row Press, 1982, p. 64. ña, y Santa (Ancash-Perú). Chimbote, Editorial Progreso, s.d. 68. PROGRAMA COBE. CONVENIO MVC-AID. Mejores Vivien- 57. PROGRAMA COBE. CONVENIO MVC-AID. El Adobe Es- das de Adobe. Lima, Ministerio de Vivienda y Construcción/Ofi- tabilizado. Lima, Ministerio de Vivienda y Construcción, Oficina cina de Investigación y Normalización, 1978, p. 8. de Investigación y Normalización, 1978, pp. 10-11. 69. CLIFTON, James R. - DAVIES, Frankie. Op. cit., p. 9.

54 Adobe Buildings some Restoration Examples

Sergio Rojo A.

Abstract Industrialization, by itself, has not managed to solve the housing needs of an explosively-growing —Some properties of raw earth used as a building population. material, relevant to the configuration and mechanical The vernacular traditions will continue to be the behaviour of structural forms, are discussed. only accessible building methods for large —and, possi- — Restoration examples are given, where the criterion bly, growing— groups of the world's population. followed was applied as a result of considering these We must add to this that industrialization brings properties. about the discredit of traditional building techniques, which are thus completely forgotten. Another reason to concern ourselves with raw- 1. Introduction ". earth buildings is the need to safeguard the cultural identity of the different peoples and to reduce energy 1.1 Need to concern ourselves consumption and pollution. with raw-earth buildings One-third of the world's population lives in * This summary deals only with structural aspects of raw earth and excludes the technical precisions which were discussed houses made of raw-earth. during the Symposium-Workshop. These will be found in other Many of the historical monuments found in papers of the present publication, as well as in the works listed different regions of the world are made of adobe. in the Bibliography.

55 1.2 Relevant properties of raw-earth —Shrinkage, which takes place as a result of drying, from a structural point of view makes it necessary to reinforce the earth or to reduce its resistance by adding sand or contraction joints. The relevant physical properties of raw-earth —The unbalance between compression-strength and are: traction-strength will lead to structural forms which are — Plasticity, which makes it possible to shape earth and solely —or predominantly— compressed: arches, vaults, produce usable structural elements. domes, columns, walls with a vertical and static load, —Solidification, which allows conservation of the forms and others, where the result of forces is contained in and of the mechanical properties associated with the the nucleus of the sections. solid state. Alternatively, vegetable or metallic reinforcements are used to compensate for the tractional weakness of Both of these properties depend on the presence earth and to widen the range of the possible structural of small particles, of clay and on the water content. forms. A solid element will return to the plastic state by water — The friction component in the shearing strength will absorption, increasing its volume and losing its mechani- make it necessary to load the sections where shearing cal properties. By desiccation and, eventually, by is critical. This implies the existence of large masses pressure, it will solidify and reduce its volume. whose inertial reaction to seismic movements is undesi- This reduction in volume —shrinkage caused by rable. the drying cycle — will produce cracks and mechanical — Fragility makes it necessary — in structures built in damage. To maintain the material within acceptable limits, it is necessary to have larger particles, sufficient high seismic-risk areas— to use reinforcements and to amounts of sand or to reinforce the earth diffusely, carefully choose the structural shapes, in order to produce ductile-type failings. by adding vegetable (or other) fibers. This will also lead to look for the most resistant The mechanical properties which condition struc- redundance which the shape will allow. tural behaviour are: We must emphasize that, except for the loss of —Compression-strength is five times greater than trac- the solid state, due to the absorption of water, all the tion — or flexotraction-strength. other properties listed are common to the different —Shearing strength is formed by a component depend- forms in which raw earth is used, as well as to brick ing on adherence and another one depending on masonry, stone rubble work, ashlar stone masonry and friction and, therefore, on pressure. The latter is concrete (not reinforced). usually more important than the first one. The combination of both properties produces a 2. Some restoration examples fragile-type of structural behaviour (as opposed to a ductile one) which is undesirable when the loads are Comments follow on the structural and design dynamic. criteria applied in four monuments where I acted as Granulometric correction, compacting and physi- structural consultant. cal and chemical stabilization contribute to fix the solid These monuments are: state throughout time, and to increase the magnitude —The Church of San Francisco de Curimon, Chile of mechanical strength, yet do not change the struc- (1972). tural characteristic of the material. Architect: Rodrigo Marquez de la Plata. —The Museum of San Francisco, Santiago, Chile (1974). 1.3 Structural forms Architects: Raul Irarrazabal and Exequiel Fontecilla. —Tower of the Church of La Merced, Rancagua, Chile The following conditions depend on the physical (1982). and mechanical properties: Architect: Mario Perez de Arce A.

56 —Tower of Hacienda Mendoza (Monasterio Benedictino) , — The advantage or disadvantage of a heavy roof calls Rengo, Chile (1983). for some comments. Evidently, for a free-standing wall, Architects: Rail Irarrazabal and Associates. which is not part of the wall-system, the existence of a considerable mass at the top of its height is clearly unfavourable. 2.1 Church of San Francisco de Curimon The situation is less clear if the existence of said The nave of the church was built in 1737, and mass —and the rigidities and links associated with it— the tower (the third one) between 1860-1890. have the capacity to integrate that wall within a system The tower is made of wood and is totally inde- having greater redundance. pendent from the nave. It suffered extensive damage A cover of ondulated galvanized steel, tightly during the earthquake of La Ligua, on 28 March 1965. screwed to the wood roof structure has a significant Part of the south wall (13 na.) collapsed and several capacity to act as a diaphragm. Nonetheless, it can not buttresses were detached from the north wall. materialize the restriction of the top part of the wall, At the time, the roof was lightweight, made of because of lack of weight. ondulated galvanized steel. The adobe walls, for an A roof made of tiles and mud over a continuous, 8 x 44 m. interior free floor plan, were 9.50 m. high. wide planking, properly nailed to the legs of the roof The section of the south wall which collapsed did not structure, constitutes a good diaphragm and forms a box have any buttresses. where the walls which are momentarily in a perpen- The wall which collapsed was rebuilt and the dicular direction to the seismic movement receive sup- lacking buttresses were added. The detached buttresses port at the top, at the expense of those which have were connected to the wall, by locking the adobes and a parallel direction and, therefore, resist easily. introducing several oak chains, placed throughout the The link at the top of the wall can be materialized height. through the shearing strength which is increased by The lightweight roofing was substituted by a heavy the pressure caused by the weight of the roof. one, made of curved tiles, stuck with mud. The height Although some slipping in this link might occur, there of the walls was lowered —except in the choir part— is still an advantage to be had as a result of the to 7 m. energy dissipated. These two operations allowed to regain the origi- — Reducing the height diminishes the slenderness of nal design of the nave. the walls and reduces the probability of overturning. Although —for a specific earthquake— it cannot be demonstrated that less slenderness implies greater Comments overturning safety, this is undoubtedly so for the family —The colapse of the central part of the south wall, far of seisms. from the interlocking corners, was due to the lack of buttresses. These have a double function: on the one hand, they 2.2 Museum of San Francisco de Santiago are equivalent to a "widening" of the wall, reducing This church, the oldest in Chile, was built between its slenderness; on the other hand, they constitute 1572 and 1618. localized weak points, which can be repaired. The cloister, which houses the Museum, was built The history of the buttresses in the north wall in the 17th century and recently adapted to museum explains the above: they were torn at the point of purposes. connection with the wall but, when breaking, they dissi- The restored part is two-storeys high; it has an pated energy and, probably, allowed the wall itself to aisle 8 m. wide, plus a corridor 4 m. wide. It is 70 m. survive the destructive phase of the quake, which has long and 9.70 m. high. a limited duration. The walls, made of adobe, are 1 m. thick.

57 The wall adjacent to the street was noticeably 2.3 Tower of the Church of La Merced, out-of-plumb in all its height. Rancagua Following criteria developed in previous projects, we decided to accept the inclination of the wall for the first floor, but not for the second storey. This is a small tower, built in the 18th century. The second-storey wall was torn down and re- Its floor plan is small, 3 x 3 m. free span, and it is placed by adobillo, i.e., a partition-wall made of oak 12 m. high. posts, filled with adobes laid on edge, with diagonal Its four walls are made of adobe; they are 1.20 wiring and plastered with mud (polvillo). m. thick. Furthermore, other existing transversal adobillo It was in excellent condition until someone, partition walls were linked to the structure, and the clumsily, made an opening for a door next to one of roof was rebuilt. It is made of curved tiles over a the corners. traditional wooden structure known as par y nudillo. This alteration —of recent date— produced The rafters and beams were carefully designed and a breakage in the wall "as if the opening was trying to reticular diaphragm was added in the horizontal plan centre itself in the wall". of the tie-beams. Repair interventions consisted in closing this eccentric opening and reopening another, previous one, which was centred in one of the other walls. Comments Reopening the old door did not produce any —The out-of-plumb wall did not show any local damage. weakness because, from a structural point of view, it Leaning may have several causes: was always "open", although a part of the wall made The most probable one is, simply, differential settlement of piled adobes blocked the way through it. on the ground outside, with regard to the inside part. The damaging opening was closed using bricks Three-hundred and fifty years of weathering and traffic and a mortar binding made of Portland cement. A final on the outside must have resulted in greater consoli- adjustment was made using expansive mortar. In a dation. certain sense, this meant the foundation-level and The inside wall —between the aisle with the series foundation-top were raised, until they were in contact of rooms and the corridor— where ground-conditions with the adobe wall. are similar on both sides, is totally plumb. Although from the point of view of mechanical In other cases, leaning is due to the thrust of the homogeneity it would have been ideal to close the rafters, faultily connected to the tie-beam. In yet opening with adobes, this was impossible to do in prac- others, it is due to permanent deformation of the walls tice: the "patch" wall settles, due to shrinkage caused —or of the foundations— of a seismic origin, caused by drying, and stops acting as support for the wall by the crushing of the material in the support-base which is over it. area. It can also be due to a deterioration of the base, By the same token, lateral interlocking is de- caused in turn by the presence of superficial water. stroyed and the whole patch becomes detached. —Safety of two-storey walls in the event of a seism is To fill in the opening with brick masonry, parallel precarious. brick piles were made. The lateral interlocking effect For this reason, the greatest efforts were made to was substituted by using horizontal reinforcements increase the integration of the structural whole and, made of welded wire mesh. therefore, its mechanical redundance. Steps were built on the contact face to receive The partition walls made of adobillo are an example the load of the uper weight on the horizontal planes, of structural elements where one can obtain a ductile trying to follow as closely as possible the shape of the response to the dynamic loads, thanks to a combination total opening, i.e. the original door plus the additional of the mechanical properties of wood and raw earth. opening, caused by breakage or failure.

58 Comments new openings and a third floor, placed at 6 metres. The damage ensued demonstrates the wisdom of These changes were necessary because of the new recommending that openings made in an adobe wall functional use: the tower is now part of the Benedictine be centred, or at least be placed away from the corners. Monastery for Women, Our Lady of the Assumption. Under static conditions, the load of the weight The new openings are small, strictly centred and —a considerable one in this case— tends to produce framed with oak. (due to the lack of symmetry in the wall) a horizontal The new floor will improve the blocking-up of slipping of the lintel with regard to the floor, on the the walls. side of the opening. This slipping increases the pressure in the area Comments of the wall which is next to the opening on the side No negative comments. of the larger wall. We should emphasize the excellence of its con- Under seismic conditions the problem increases struction; the symmetry of design and the absence of because the larger wall, which is more rigid, takes a weak or critical points. percentage of the horizontal load exceeding that which The static pressure in the walls is close to 2 would correspond to a simple distribution of that load kg/cm' and dynamic compression — for a seismic design in function of the relative areas. according to Standards— does not exceed the former The free end of the larger wall is the critical in more than 50%. This is due to the lack of slender- area, and this is, precisely, the one that suffered ness in the total structure. damage. The floors (mezzanines) do not represent more Finally, the corner area in a tower such as this than 1,3% of the total weight of the tower. We emphasize is the most valuable one from a structural point of this situation because it is usual in adobe and quite view, for it is composed of two interlocking walls. different from the one existing in concrete or steel A poorly-placed opening destroys this valuable structures. element. In an adobe tower (or one built with raw earth in any form) with considerably thick walls, it is not 2.4 Tower of the Hacienda Mendoza, Rengo realistic to suppose masses concentrated at floor levels This XVI Ith century tower, possibly built after to study the structural response to seismic loads. 1655 was used both for representative functions and as a watchtower. Bibliography It has a 6 x 6 m. free-span ground plan and is Construire en terre CRAterre. Editions Alternative et Paralleles 12 m. high. Walls are made of adobe, 1 m. thick and Collection AnArchitecture. Paris, 1979. it has floors placed at three and nine metres. (Contains detailed technical information and an abundant It is perfectly conserved, due to its excellent bibliography). construction. The floors interlock the walls securely Des architectures de terre. Centre Georges Pompidou/CCI. Paris, and, apart from the floors, it has a number of inter- 1981. La proteccion de monumentos historicos en areas sismicas. PN UD/ mediate oak chain reinforcements. UNESCO, Lima, 1983. Intervention was necessary in order to add some (Publicacion del Proyecto Regional de Patrimonio Cultural).

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75:7147 Assessment of Structural Faults and Monitoring of Structural Movements in Adobe Buildings and Ruins

Todd Rutenbeck

The assessment of structural faults in adobe portant. Signs of weakened or moist adobe along with structures normally begins with a visual inspection and signs of damage from current building use should be a study of the structural history. Locating structural observed. Most important, however, are signs of re- cracks and deducing their probable causes is essential. cent change in the structure. Pieces of or adobe A plumb bob will help in locating severely out-of-plumb that have recently fallen, cracks that have become wall sections, and profiles of the worst sections can be wider or longer, and new structural cracks all indicate plotted to determine the likelihood of failure. Sagging current structural movement. beams, floors, or roofs indicate structural movement Unstable structural elements will fall into two and possibly weakened structural members. In addition general categories: (1) those whose geometry or mate- to obvious current structural defects, conditions likely rial strength is so unstable that small increases in to cause future problems should be observed. Problems loading could cause instant collapse, and (2) those with surface drainage, soils, vegetation, moisture, ani- having defects that are slowly increasing and may lead mals, and roof drainage are a few examples. Struc- to collapse in the future. Items such as crumbling tural history items such as dates of known seismic adobe blocks, detached plaster, severely leaning walls, activity, sources of vibration, dates of past repair work broken beams or columns, and loose adobe or brick or major damage, data from past structural studies, and could be included in the first category requiring im- photographs showing past structural condition are im- mediate repair work. Items in the second category are

61 more difficult to deal with. Because of the cost of cates that the wall is already at the balance point, it repairs and because of preservation considerations, it is likely that the wall will fail instantly from a single is necessary to separate apparent structural defects event such as vibration or high wind loading. Monitor- from actual structural defects. The wall that leans ing may show no gradual changes in crack width slightly may tilt more each year until it fails. It may, and give a false sense of security in this dangerous however, have been built out-of-plumb and not moved situation. If, however, the top of the wall must tilt out since, and thus be in no danger of failure. Cracks in several millimeters before it is in danger of falling, adobe walls or domes may widen each year due to monitoring would be appropriate. Even in this case the foundation defects and eventually lead to failure. They monitoring effort would be wasted if the decision to could also be due to temperature or moisture changes build buttressing walls had already been made or if that are seasonal, or due to shrinkage or foundation the monitoring was done with insufficient accuracy to settlement that took place immediately after construc- predict movement trends before the critical angle of tion, and thus pose no structural threat other than tilting was reached. Only a well planned monitoring leaking water. Vibrations from railroads, highways, or program with definite goals and appropriate instru- sonic booms can damage structures, but in some cases ments will be useful in making preservation decisions. they are harmless. Such considerations often lead to The purpose of structural monitoring, then, is to starting a structural monitoring program to measure detect gradual structural movements that can lead to gradual movements and determine which apparent de- collapse. A well designed monitoring program allows fects are actually moving toward failure. definite decisions to be made based on the results. If Structural monitoring can be a very valuable no progressive movements are found, the historic fabric telx_onique for evaluating adobe structures, but it can be left unaltered. If progressive movements are sometimes fails due to poor planning. Frequently instru- detected, stabilization work must be carried out in time mentation is installed in a structure with no clear to prevent collapse. It is therefore necessary to be able purpose. There must be a definite preservation decision to distinguish between progressive movements that will that the data will help to decide. For example, lead to failure and seasonal changes that are harmless. seismographs are frequently installed in historic struc- It is also necessary to know how much movement can tures where damage from traffic vibration is suspected. be tolerated before failure. This determines the needed Several years of data gathering takes place to record accuracy of the instrumentation to be used. the intensity and duration of vibrations loading. It Structural movements, such as crack width change, then becomes apparent that while the level of seismic wall tilt, deflection, and foundation settlement are loading has been determined, no one knows if this usually plotted as movement versus time. Thus, in vibration intensity is sufficient to cause damage to the monitoring a structural crack, it is not necessary to structure. What was actually needed was a concurrent measure the existing crack width. A gage is installed measurement of structural damage such as increasing across the crack and the reading on the gage is crack width that could be correlated to levels of recorded. This initial reading is subtracted from each seismic loading. Then a decision to limit vehicle size subsequent reading to determine the change since gage to stay below the critical vibration level could be made. installation. These changes in crack width are then Other problems in planning monitoring programs in- plotted versus time in days. The fluctuations that this clude a false sense of security from monitoring a struc- plot shows are composed both of seasonal changes and ture that is likely to fail instantly, monitoring when the of progressive movements. If only seasonal changes are decision to repair the structure has already been made, occurring, the plot would fluctuate above and below the and using instruments of insufficient accuracy. For zero movement line, but after a year of data plotting example, suppose that the width of a crack between a the total change would still be approximately zero. If badly leaning wall and an abutting wall is to be moni- progressive movements were taking place, the plot tored. If plotting the profile of the leaning wall indi- would continue to move away from the zero line. The

62 seasonal movements would cause variations in the plot, (when the center of mass is above the outer edge of but the general trend in one direction would be ap- the wall base) without failing merely because adjacent, parent. more vertical sections of the wall provide support to Seasonal variations have two causes. The first is the leaning sections through friction between the adobe composed of actual changes in the structure due to blocks. Thus, most estimates are on the conservative seasonal or daily changes in loading, temperature, and side, treating a failing section as if it were free- moisture. The second is due to changes in the instru- standing and ignoring the support of adjacent sections mentation. These include thermal expansion and con- which is difficult to compute. traction of the instrument and its mounting brackets, The needed instrument accuracy depends on the reading errors, and instrument inaccuracies. There is a estimated amount of movement that will take place tendency when first starting a monitoring program to befcre failure. If a movement of only ten millimeters spend too much time on instrument seasonal variations. could cause failure, an instrument accurate to 0.01 mm. Computing the thermal expansion of the brackets and would allow 1000 units of movement before failure, the instrument, and applying temperature corrections thus allowing gradual movements to be observed before to electronic gages and their readout devices, is seldom failure. An instrument with an accuracy of 5.0 mm. necessary. As data are plotted, the difference in would allow only two units of movement before failure, progressive movements and seasonal movements be- nct enough to detect gradual trends. comes apparent. Since the main purpose is to detect Monitoring efforts often fail from lack of ac- progressive movements, it is not normally necessary to curate instruments. Glass slips glued in place across separate the two types of seasonal movements. The cracks or measurements taken with a ruler between two instruments used, of course, should have as small a pencil marks often yield useless results due to low variation with temperature as possible, but once the accuracy when the use of a $60.00 mechanical dial installation is completed, it is seldom necessary to gage could have given results accurate to 0.01 mm. This ccmpute these variations. is a small cost compared with the personnel costs Determining how much progressive movement involved in taking and analyzing the data. can be tolerated before collapse occurs is a function Instrument costs vary widely depending on the of structural geometry. A vertical crack in a free- needs of the monitoring project. Crack width and standing wall could widen indefinitely without the dan- deflection can be monitored accurately using 560.00 ger of collapse so long as the wall segments remain mechanical dial gages provided that it is possible to vertical. If a free-standing wall segment is tilting as a get to the gages periodically to take readings. If whole, it is easy to compute what degree of leaning scaffolding or manlifts are necessary to reach the gages. will cause it to fall. Most structural faults are not so it may be cheaper in the long run to install $700.00 easily analyzed and most predictions of how far electronic gages that allow a remote readout. Electronic movement can progress before failure are merely esti- gages also allow automatic electronic recording of data mates. Even in the simple case of a long free-standing in cases where continuous recording of data is needed. adobe wall that is leaning dangerously, the idealized Soil and foundation settlement can be detected ccmputation of the amount of movement necessary to with a precise surveyor's level. While initial costs of cause failure will not exactly represent the wall. The precise leveling equipment may be about $9000, there wall is stable as long as the center of mass of the is little additional cost for the purchase of brass monu- wall does not tilt beyond the center one-third of the ments needed at each site for reference points. Thus, wall's base. At this point, tensile stresses develop, and once the equipment is purchased, it can be used at adobe with mud mortar has little resistance to tension; numerous sites at little additional cost. Such equipment however, the wall may not fall. As tensile cracks (consisting of a precise level with optical micrometer, develop, the wall may bulge and change its shape. tripod, and invar rods with rod stands) reads elevation Some segments may lean beyond the balance point directly to 0.1 mm. with estimates to 0.01 mm. In struc-

63 tural monitoring work, closing errors of less than 0.20 brackets requires considerable skill to estimate the mm. are frequently obtained. center of the string that always swings slightly and skill Variations in wall tilt can be detected by several in reading the calipers. A tilt meter would give a methods depending on the accuracy needed. Wall pro- digital readout that can simply be written in a data files can be plotted periodically using two plumb bobs book. For crack width, the dial gage is usually easily hung one on either side of the wall a known distance read, but there is less chance of error with the digital apart. Comparing profiles could then detect any large readout of an electronic gage. Remote readouts also changes in tilt. More accurate readings can be obtained reduce the chance that the gage installation will be by fabricating simple plumb bob brackets. The brackets accidently disturbed. Thus, the ease of taking accurate are permanently attached to the wall. The top bracket readings is a consideration. Fortunately, however, most holds the string in an exact location. The plumb bob occasional reading errors are similar to seasonal varia- is suspended from this string, which extends below the tions: they become apparent as the data are plotted. lower bracket. The lower bracket has a reference It would be almost impossible to make reading errors surface for measuring the distance between the string consistently in a manner that would indicate progressive and the bracket with machinist's calipers. Plumb bob movement when none exists. brackets are capable of a reading accuracy of about one millimeter. Electronic tilt meters give much improved Properly used, the monitoring of structural accuracy, but cost about $1000 each. movements in adobe buildings and ruins can help in While accuracy, cost, and access are the most assessing apparent structural faults. While it cannot important factors in choosing instruments, there is an warn of instantaneous collapse, it can warn of structural additional important factor: the skill of the data gather- movements that gradually increase toward collapse. By er. In many cases the person taking the readings is determining which apparent defects are actually not technically criented and good results depend on dangerous, and which are harmless, structural monitor- using instruments that are easy to read without error. ing can prevent unnecessary modifications of historic For example, determining wall tilt with plumb bob fabric.

64 A Conservation Survey of Adobe Buildings ".

Anthony Crosby

In this presentation I will emphasize a logical process may also be interesting and in some cases way of looking at an adobe building in order to deter- necessary to be able to determine the cause, but a mine the problems, or the effects, which result from the knowledge of the process without eliminating the cause processes of deterioration. I will begin by discussing will not result in a long term solution. the process of examination, then will show specific The most logical way to determine the causes of examples of several systems to look for specific answers deterioration is to approach the survey by looking at to questions concerning the processes of deterioration. the visible signs of deterioration and then going back The conservation survey of an adobe building or through the process to the cause. Another equally structure is, simply, the process necessary to determine important way is to look for potential causes. As an the causes of deterioration. Once the causes are de- example one would look for the actual causes which termined they can be either eliminated or accepted if resulted in basal erosion. The investigation may de- elimination is not possible or practical. The important termine that the cause is an excessive amount of rain word is "cause". While the actual visible deterioration water splash, and that there is no surface runoff or will need to be repaired —or it may become the cause of further deterioration itself, the repair without ad- dressing the cause will not be long-lasting. The actual ° Abridged version.

65 capillary moisture problem. In another location the 1. Causes of basal erosion investigator is aware of an extremely high water table. a. Tunneling by rodents The high water table is a potential cause of a serious b. Wet/dry cycles problem which should be investigated. Any survey c. Freeze / thaw cycles should include looking for both the actual visible de- d. Splash terioration and its causes. e. Hydration/dehydration of soluble salts The subject of the survey: 2. Causes of surface erosion A. Deterioration, the results of problems: a. Wind driven abrasives b. Running water i. Basal erosion c. Insect activity Surface erosion 2. d. Freeze/thaw cycles 3. Cracks and bulges e. Wet/dry cycles 4. Slump or creep 5. Upper wall displacement 3. Causes of cracks, bulges and leaning 6. Collapse a. External loading b. Internal wall moisture B. The problems, or causes of deterioration: c. Increased compressive loading I. Running water 4. Causes of the failure of protective surfaces 2. High wind 3. High water table a. Same as surface erosion, above 4. Excessive ambient relative humidity b. Internal moisture 5. Concentrated rain water 6. External loading 5. Causes of wall collapse The methods for determining the results and the a. External loading problems can be extremely complicated and technologi- b. Wall moisture cally advanced, such as microwave and laser technolo- c. Decreased bearing area gy. Some others are less sophisticated but can also be 6. Causes of upper wall displacement expensive or otherwise unavailable. However, the re- sults of much of this type of equipment can be repli- a. Wet/dry cycles cated to some degree by techniques which are more b. Wall moisture ordinary. Probably the most important tools are those Several of these processes such as wet/dry cy- such as plumb bobs, levels, probes, and thermometers cles, freeze/thaw cycles, and internal wall moisture which are available to most anyone. But even more occur more often. Others seem to be problems in fewer simple is the investigator who has a comprehensive cases. understanding and respect for the material. It remains to be seen, but this most simple tool may be more rare than the most technologically advanced. D. Explanation of the Processes 1. Wet/dry cycles C. Causes (Processes) a. Associated with soluble salts What are the actual processes which result in b. Associated with types of clays such things as basal erosion, wall collapse, cracks and c. Number of cycles, length of cycles, important, but bulges? What actually causes these results? difficult to access

66 2. Freeze' thaw cycles 7. High ambient relative humidity a. Dependent upon moisture 8. Earth movement, lateral force b. Dependent upon temperature Of these eight common sources of adobe deterio- ration, five are directly related to the presence of 3. Capillary effect moisture. Four of those five could be simply grouped a. Critical moisture content as the one common source, free water. b. Dependent upon a source c. Mechanism Summary 4. Internal wall moisture These are some of the more common causes which initiate a process that results in visible deterioration. a. Internal condensation We have not talked very much about corrective meas- b. Capillary condensation ures. Some are obvious. If the upper portion of a wall c. Upper wall leak becomes saturated because of a leaking gutter, then d. Effects mechanical properties repair the gutter. The solutions to problems of high water tables, improper drainage, or the lack of a water- 5. Running water proof foundation are not as obvious and are often not a. Surface wash as simple. either. We will be discussing solutions during b. Increase moisture content other sessions of this conference. One more word in closing. It has been said 6. Increased loading before, but it is important to repeat. To be able to a. Reduced loading area identify deterioration, to look for problems, and to search for solutions, the most important tool that anyone can have is the knowledge, or more appropriately, an E. Actual Sources understanding of the material; an understanding of its I. High ground water table advantages and disadvantages. An understanding that 2. Inadequate drainage will lead you to know which processes of deterioration 3. Leaking pipes can be stopped and which ones simply have to be ac- 4. Rodents cepted. It takes an understanding of adobe to know 5. Insects that certain visible deterioration should be accepted 6. Leaking roof, gutters, etc. and hopefully managed, rather than eliminated.

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}littgrAiii Earthquakes and Adobe Structures

Julio Vargas Neumann

1. Introduction b. Fragility in the face of natural disasters The first buildings made by man were made of (earthquakes, floods). earth; still today, in many parts of the world, earth is c. Some interior space is lost, due to the thickness of the basic building material. the walls. Edifices built with earth have a series of advan- d. Socially, they are often not accepted. tages and disadvantages, as do those built with any In the industrialized nations, modern technology other material. has developed new materials during the last decades. Some of the advantages are: However, less efforts have been made to solve or control a. They are simple to build. the deficiencies of primitive or natural materials used b. They are economical. in the Third World. c. They have good thermal and accoustic isolation. A review of the advantages and disadvantages d. They can be built without energy consumption. of earth as a building material leads us to conclude that the advantages are increasingly important in The major disadvantages are: today's world, while the disadvantages can be over- a. Durability is precarious (subject to erosion, effect come with the help of the new technical developments of water, etc.). and of state-supported educational programmes.

69 2. Earthquakes oscillator in the shape of an inverted pendulum. (See The earth's crust is divided into some 20 plates Fig. 1). We are imagining the mass of the building which displace themselves over the earth's surface and concentrated and connected to the ground by a hoop interact with each other. In the regions where these which would represent its flexibility, having a certain plates meet, most of the seismic energy of the world is degree of shock absorption. This equivalent model dissipated. Nonetheless, in other parts of the globe, would undergo a movement at the base — this we would faults in the earth's crust produce earthquakes as well. also represent, in its simplest form, by the registration When an earthquake takes place, a dynamic of an earthquake, such as the one seen in Fig. 2-a. This movement is produced at the base of a building; this registration produces movements in the mass which, if induces vibrations throughout the different parts of measured, would give the line found in Fig. 2-b. It is the edifice. Engineers can estimate the amplification easy to see that this last movement depends on the levels of these vibrations in terms of displacement, ve- magnitude of the mass, the flexibility of the hoop, its locity and acceleration, and thus design the buildings shock-absorbing capacity and naturally, on the registra- adequately. Structures must be prepared for this type tion, of the earthquake which originates the movement. of movement; this means one must first know the dy- The result of the vibration may or may not namic behaviour of the building in order to produce produce damage in the model. This depends on the a correct design. strength of the hoop as well as on a basic concept: its ductility —that is, its capacity to deform itself in 3. Seismic Behaviour of Adobe Buildings the inelastic range —which is when it actually dissi- pates energy. In general, the simplest way to represent or A good seismic-proof design involves a series of idealize a structure with vibration at the base is by an concepts simultaneously. Trying to sum them up, we

D

Fig. 2-a. Soil movement registration.

Fig. 1. Simplified dynamic model. Fig. 2-b. Structural mass movement registration.

70 might say that the following are the characteristics quality of the adobe and the mortar is rather low; the required in a building: ground has a high content of sand and little plasticity, due to lack of sufficient clay. Shear resistance is very —Lightness. so as to diminish the mass and. therefore. poor in this type of masonry. A proof of this is that the forces between the different elements. the slender• elements of the masonry have practically —Absence of critical points of effort-concentration. This disappeared, and even those recently restored (Temple is obtained through adequate architectural design of the Moon) are severely cracked. Use of this material which supposes: is due to the location of this monument, near the ocean, • A symmetrical distribution of the different elements. in a sandy, desert area. - Uniform density of walls and elements. - Continuity in the shapes and volumes. - Uniformity in materials, rigidity and ductility. b. Slender masonry or wall-type elements - Adequate connections. which will guarantee the possi- bility of ductile movements. Ancient buildings (pre-Inca or Inca) built with - Sufficient strength (resistance), so as to withstand these elements have generally disappeared, as a result the thrusts. of earthquakes. Those left standing have withstood the • Limited deformability. centuries either because they were buried or because their slenderness was limited, i.e. the relation between We will point out two types of earthen height and thickness was not too high. Colonial adobe buildings and analyze their performance: buildings belong to this type of masonry. — Buildings made of masonry (adobe and tapial). We can distinguish two sub-types within this —Continuous systems (wood or cane with mud — group: ""). — Linear walls or enclosures. — Buildings with walls at right angles from each other, orthogonal walls (houses and other buildings). 3.1 Masonry Buildings The seismic behaviour of linear walls is interest- a. Massive masonry ing. The first concern is overturning. However, under dynamic action the walls vibrate transversally but not This type was widely used in antiquity to build in a uniform manner, i.e., while parts of the wall tend monumental-type structures, such as temples and for- to collapse toward the left, others tend to collapse tresses. On the coast of Peru, the Fortress of Paramonga, toward the right, forming a sinusoidal wave when seen the Temple of the Sun at Pachacamac, Puruchuco and from above. This undulation produces vertical cracks others are examples of this type. which divide the wall in parts, and if the movement The large dimensions of their principal elements persists, some of them, and eventually all of them, make them invulnerable to earthquakes. In general collapse. these buildings have great rigidity and therefore the The dynamic stability of the walls to overturning vibrations they undergo are practically the same as is a matter of special interest. A study has been those in the foundation-ground, i.e., the amplifications undertaken in order to define the characteristisc of of the movement, a characteristic structural response, said process. Because earthquakes have impulses that are absent. change direction in fractions of a second, and the wall In these structures the most acute problem is has a strong rotational inertia, it is not easy to produce their durability, and not precisely the seismic problem. the collapse of a part of the wall. Pachacamac, for instance, built with adobes and mortar The results of this study will allow us to find out of the same quality as the block, is an example of how severe an earthquake the Inca or pre-Inca en- seismic resistance due to its structural shape. The closures, still standing today, are able to endure. Thus

71 we would be able to find out the uppermost limit for notably increase their stability, is to use reinforcements the earthquakes which have taken place from pre- made of ductile materials (wood, cane, wire, etc.). This Columbian days to the present. This information will is as true for new buildings, where it is easier to place be very valuable for the studies on Seismic Risk which them, as it is for existing ones, where these rein- are carried out for huge works of infrastructure, such forcements can be placed exteriorly. as Nuclear Plants, Hydroelectric Power Plants, etc. which must be built taking into account earthquakes with long periods of recurrence (100 years, 200 years, 3.2 Continuous Systems etc.). The seismic behaviour of adobe buildings with These are buildings where wood or cane are used walls that meet each other is even more complex, and as structural elements and which use earth to create it is not possible to idealize this behaviour in practical enclosing elements (walls and roofs). terms. The seismic behaviour of this type of building can Because of the fragility of the material, the be very adequate if an integral and flexible behaviour disorderly vibration of the walls —each one having is achieved. This depends on the quality of the con- different dimensions and support-conditions— produces nections, which constitute the critical points. flection loads and shearing loads which generally It is important to reduce as much as possible concentrate where the walls meet. the weight of the earthen components and make sure Once vertical cracks appear where both walls of the durability of the wood or cane. meet, each one of them vibrates separately, as in the case of linear walls; what differs is that normally, they collapse toward the outside due to interaction between 4. Research Studies Undertaken at the them. Catholic University Secondarily, some shearing cracks of a diagonal The Department of Engineering at the Catholic type also appear. Their critical paths preferably follow Pontifical University of Peru has carried out several lines near the corners of windows and other openings. research studies dealing with adobe and earth con- It is essential to know these types of faults when structions. The titles of these published studies are re-constructing, as well as when first building an edi- listed in the Bibliography (see last page of this paper). fice. It is crucial to adequately treat the meeting-place We will briefly describe their content here: of walls, as well as corners, and all openings. Another critical area in adobe buildings is the Reference 1 place where the roof meets the walls. The weight of the roof concentrates horizontal thrusts in the upper Fot the first time, the static test method for part of the wall when an earthquake occurs. This structures was used with natural-size structures placed produces partial faults or overturning of the walls, on a leaning platform 4 m x 4 m. A series of structures which in turn brings about the collapse of the roof. with 4 meeting walls 2.6 m x 2.6 m x 2.4 m high (with Thus, it is possible to conclude that a basic factor no roof) and with a variable number of openings and for the stability of adobe buildings is the relation different reinforcement elements, were tested on this between height and thickness (width). platform whose inclination could simulate horizontal The size of openings and their place in each static accelerations, which were 23 to 42 per cent of wall (they should be small and centred) , as well as the the acceleration of gravity. shape of the floor-plans (rooms should tend to be square) , are other important factors. Reference 2 The only way to get the different walls of a building to work together and not separately, and to Basic information was obtained on various elastic parameters which are interesting for buildings made 72 of earth. This was done through different tests: cubic masonry, the aim was to explain the differences regis- and prismatic compression test, flexo-traction (a Bra- tered, which are due principally, to the adhesion of zilian test) diagonal compression test, shear, flection the mortar to the block. in walls, overturning, etc. As a result of this study, a classification of different mortars was proposed, in view of establishing Reference 3 standards and norms. Ductility was sought by using cane rein- forcements, and the data for shear resistance and Reference 6 others was revised, continuing the experiments begun in Reference 2. Information obtained will be used to The direct shearing test, which is part of the make proposals for the National Building Code. Good current Adobe Norm (Norma de Adobe) was perfected. levels of ductility were achieved. See Fig. 3. The cyclical behaviour of adobe masonries was studied; this allowed evaluation of the dissipation of energy inherent to internal friction. This information is useful when applying the Seismic-Proof Norm to adobe buildings.

Reference 7 With support from AID (Agency for International Development), a research project was undertaken to study appropriate soils for building with earth. The reasons of their appropriateness (or lack of it) were considered. A good soil must have adequate plasticity, and, at the same time, adequate granulometry. Adequate drying conditions for blocks and mor- tars, and the control of cracks by adding sand (and Fig. 3. Ductility in wall reinforcements (Cane mesh). Monotonic straw) are crucial, in order to obtain resistant ma- load. sonries. The diagonal-compression test of a small wall 60 x 60 cm. (made of adobes and joining elements) Reference 4 is the best way to ascertain the resistance of masonry. This programme was carried out in coordination A lab test, which allows optimization of the with the Engineering Institute of Universidad Autonoma composition of the soil (using sand mixtures) is shown de Mexico. Its aim was to corroborate the sharp in Fig. 4. Here, resistance to compression Sigma m is differences existing between the Peruvian and the Mex- related to the IP-Alfa Parameter, the product of the ican tests for shear-resistance in masonry. These Plasticity Index, IP, and the quotient between the weight differences are negligible where individual adobe of the soil which passes through the 40 wire-meshes bricks are concerned. and the total weight. It can be observed that there is an optimum range for IP-Alfa, which does not occur for other 5 Reference parameters. Through a study of variations in the constitution When sand is not available to modify the granu- of the mortar and the adhesion techniques used in lometry of the soil, it should be used to control

73 cracking. It can be used up to 4 or 5% in weight. (See the faults, in order to repair them and, additionally, Fig. 5). to modify the structures in order to make them seismic- proof in view of future earthquakes. One must not only 13 repair the local fault, but design a global anti-seismic behaviour for the building, which will prevent future

1.0 faults. We can summarize this process of assessment and

0.5 repair as follows: —Classification of the damage. --Structural analysis of the damaged building. 00 0 5 1P-Alf a 10 15 — Interpretation of the cause of the faults. Fig. 4. Wall resistance vs IP-Alfa. —Designing a reinforced or modified building. —Follow-up and evaluation of repairs.

1.8 Referring exclusively to adobe buildings, it is necessary to first classify the damage from a structural 1.6 point of view:

1.4 a. Light damage

1.2 Cracks in non-structural elements (secondary walls, ornaments, etc.). Erosion or loosening of 1.0 and stuccoes. Faults in the roof-covering. Slight cracks in floors. Window-frames out of joint. 0.8 b. Moderate damage OA • Mortar: PUC-Ichu Small cracks in structural elements, places where 4 Mortar: PUC-asped 0.4 walls meet, window and door angles, connecting points between lintels and walls, connecting points between 0.2 roof (beams) and walls. Superficial erosion of walls. Loosening of secondary elements in the roof system. 0.0 0 1 2 3 4 Walls slightly out-of-plumb. Large cracks in floors.

Fig. 5. Masonry resistance vs straw content i n mortar. Mortar: Displacement of door and window-frames. PUC-Straw: 100-C. c. Severe damage Cracks in the structural elements; partial de- 5. Evaluation and repair of damages tachment of walls and roofs. Walls severely out-of- The repair of faults produced by earthquakes, plumb. Faults in the main roof-beams. Differential unlike other faults, requires a careful analysis of their settlement of foundations; severe erosion in walls. cause, and not only the type of repair which will give Structural analysis must take into account several them back static stability. One must give the whole aspects: edifice the dynamic stability it did not possess (since —The quality of the masonry. it failed). —Reinforcements (existence and types). In other words, the philosophy underlying re- — Location of resistant elements. pairs consists in assessing the cause and magnitude of —Idealization and evaluation of thrusts.

74 in view of earthquakes, interpret Preventive measures This information makes it possible to which include evaluation and eventual repair of the cause of faults, after examining their location and buildings in order to make them seismic-proof are ty pe. required. Unfortunately, this task is often ignored. It is probable that there will be a coincidence Thus it seems logical, after what we have just stated, as to which elements undergo stress in theory, and that general restoration interventions should include what in fact happened. This will require an analysis to modify experts in seismic-resistance within the interdisciplinary of the existing resistant elements, in order team of specialists. In this manner, the potential the concentration of stresses. permanence of the monument is significantly increased If there is no coincidence, other explanations and —equally important— the cost of repair inter- for the faults have to be sought; the quality of materials ventions is lowered, for it would be much more expensive should be analyzed, as well as the details of connec- to repair this building after an earthquake has occurred. tions between elements, the reinforcements placed in To think that a building is strong because it the different elements, as well as the local concen- has endured a number of earthquakes is as erroneous tration of stresses in short columns, poorly-placed as it would be to assume that a patient who has openings, etc. undergone several heart attacks is presently in excel- Often, faults will reveal obvious defects in lent health. construction which are easy to repair individually and have no relation to the behaviour of the whole. But is Bibliographical References other times — and this is why a structural analysis required— they can only be explained by an integral 1. Blondet, M. y Corazao, M. "Estudio Experimental del Com- study of the edifice (lack of rigidity in a certain portamiento Estructural de las Construcciones de Adobe frente a Solicitaciones Sísmicas". direction, or torsional rigidity, or high eccentricities in Premio Sayhuite. Banco Peruano de los Constructores. Lima, 1973, the distribution of elements, or discontinuous rigidity, 2. Blondet, M. y Vargas, J. "Investigación sobre Vivienda Ru- etc.), ral". Departamento de Ingeniería, Pontificia Universidad Católica Obviously, all solutions must be consulted with del Perú. Lima, 1978. experts in restoration and conservation of monuments, 3. Vargas, J. y Ottazzi, C. "Investigaciones en Adobe". Departa- mento de Ingeniería, Pontificia Universidad Católica del Perú. so as to preserve the historic value of the monument. for Lima, 1981. In ending, it is important to stress the need to decide 4. Hernández, O. y Meli, R. (México) — Ottazzi, G. y Vargas, J. a follow-up, in order to assess the repairs and ( Perú). "Investigación Cooperativa de Construcciones de Adobe". on their adequateness in future cases. Institwo de Ingeniería, Universidad Nacional Autónoma de Méxi- co y Departamento de Ingeniería, Pontificia Universidad Católi- ca del Perú. 1980. 5. Vargas Neumann, J. "Albañilería de Adobe con Variaciones 6. Prevention vs repair de Mortero". Departamento de Ingeniería, Pontificia Universidad Important efforts are made today to create an Católica del Perú. Lima, 1979. 6. Ottazzi, G. y Torrealva, D. "Comportamiento de Elementos de awareness of the need to estabiish preventive measures Albañilería de Adobe en Ensayas de Corte". in view of natural disasters, such as earthquakes, IV Congreso Nacional de Ingeniería Civil. Chiclayo, 1982. floods, hurricanes, etc. 7. Vargas N., Bariola, J., Blondet, M., Villa García, G., Ginocchio, a very Monuments should be looked after in J. "Propiedades del Suelo para Elaborar Albañilería de Adobe". special way, for they represent our historie and cultural Seminario Latinoamericano de Construcciones Sismo Resistentes de Tierra, Lima 1983. heritage.

75

5 4414b0i' ftVkl'1.0 thilP •!.*>41f :14 •4; • Ádiíeillf .:fi t&i•-"%• .343.13 ~t-,;,4‹3 ;,;-w .bri./qsít rti .2t , — , ,y‘. . Affillik44.141"kt rro401k,...k;ik '.;- —glifj- 4-10111:'!" ' ,11Mil li ' bs4.-.• 44,1;~*>M010.no'->14-4~. 44 ui %41.4. -k--k!:Itil wii J4; AO_ k % ^o,. hs3mx31 1 14, - ?...104144, -'4'i14'";tf".:4& otiS1~1.-.0‘.ttÀrs,,-';r4Xt-ifri,-4‘ s.ii',te; bi:tk,35, 1001-~'' .014~~ir-~i:»44"7:j44.ili$MtP44%~t, ,ti: ,,J;-: _t .~,,,41- :, %.34:-.44., , -.-4~-._____. ,311*.., ._, 4444/*If4-iid.3t. . . ,33,;-.;... -34i: --110~ .4 luiNkdr z*.,4 ',43".-4Fxr.iiimairlglikAki"" Ï400..."'aw...,‘ 19 tluilt.:: ' ii,.*0?,bfifi~ li - ^"Sflifr44 4 '4110,34 4tlikk.7..4 f 0141.5C1.:t{ 4, Y;44111 4rti 14Àár's1 ~t'44 Ni; zïr.4t --- ”dirs ,n/(41k4 Investigation of the Long-Term Effectiveness of an Ethyl Silicate-Based Consolidant on Mudbrick

Seymour Z. Lewin Paul M. Schwartzbaum

was done by placing the mudbrick surface opposite Introduction the paint layer in a shallow pool of a 50% solution of The five thousand year-old mural paintings at Wacker Stone Strengthener I-1 in toluene. The mud- Teleilat Ghassul, Jordan, are on a support consisting of brick absorbed the impregnant through capillary action. sun-dried mudbricks, about 13 cm. in thickness. One and when it was judged to be fully saturated, the piece of these, found in 1977 to have been broken into 33 was covered with aluminum foil to retard evaporation, major pieces and many fragments, was restored, consoli- and left to cure for three days. dated, and reassembled in a mount suitable for instal- The requisite degree of strengthening of the lation in the Amman Museum. The details of the tech- previously very friable mudbrick did occur, and this nique employed have been fully reported by Schwartz- contributed significantly to the trouble-free manipu- baum, et al., at the Third International Symposium on lation and mounting of the pieces to reconstitute the Mudbrick Preservation.' total mural. The chemicals employed were as follows: the Although the use of this ethyl silicate-based paint layer was strengthened by the application of a consolidant served its primary purpose, it remains to be 7% solution of Paraloid B72 in acetone, and detached determined what the long-range effect will be. areas were treated by injecting 15°/o Paraloid B72 The treatment of this mudbrick was completed between the strata. Small fragments along the fractured in 1979, and several specimens of both the untreated borders of the pieces were glued in place with 50% and treated material were retained for future study. Vinavil (a polyvinyl acetate emulsion). It was next Consequently, at the present time we have available necessary that the mudbrick support of the paint layer samples of the treated mudbrick that have aged under be consolidated and strengthened so that it would ordinary indoor ambient conditions for 4 years, as well resist damage and attrition through handling in the as untreated specimens of mudbrick from the original process of reassembling and mounting the pieces. This source which can be given the same type of impreg-

77 nation in order to produce freshly consolidated samples Thus, it is the clay content of this mudbrick as comparison standards. The present paper reports that is of crucial importance for the initial success of the results of such a study, i.e., determination of the the consolidation treatment. effect of 4 years of normal aging on the composition Measurements were made of the volume of the of the silicon ester-based impregnant. silicon ester formulation that is imbibed by the mud- brick through capillary rise from a shallow pool of the liquid in which a sample of the solid is placed. It was A. Properties of the Teleilat observed that a 23.29 gram specimen of the untreated Ghassul Mudbrick Teleilat Ghassul mudbrick imbibed, by capillarity, 3.54 g The mudbrick from Teleilat Ghassul consists of the Wacker H solution (density = 0.9 g/ml) in 45 principally Of quartz pebbles ranging from 0.1 to 2 mm minutes, and 4.01 g in 2 hours. The latter value in dimensions, calcitic skeletal debris 0.01 to 1 mm in corresponds to a porosity of 19%, i.e., 19 milliliters total dimensions, and clay particles in the size range 0.002 volume of accessible pores per 100 grams of the solid. mm and below. It is the clay component that serves to bind the mud together when a brick is fashioned. When wet, the clay absorbs water intramolecularly B. Analysis of Siloxane Composition and swells; as the mud dries, the clay particles are drawn together into close mutual contact by surface Our analysis of a batch of Wacker H solution which tension forces, and when dry, they are hold to each had been stored in an unopened bottle for about two other principally by the Coulomb forces arising from years, shows the composition to be: 15% solvent (princi- hydrogen-bonding between the —OH groups on adjacent pally toluene), 35% methyl triethoxysilane (monomer + particles. dimer), and 50% tetraethoxysilane (monomer + dimer). It is these —OH groups on the surfaces of the This mixture of silicon esters reacts with moisture tiny clay platelets that are responsible for the inter- or reactive —OH groups by undergoing hydrolysis and action with the silicon ester-based consolidant, and that condensation. For an explanation of the nature of causes the consolidant to cross-link adjacent clay par- these reactions, and the factors affecting their rates, ticles into a three-dimensional network. The molecular see Reference 2. nature of this cross-linking is illustrated in Figure 1. As these reactions proceed, ethyl alcohol ( = ethanol, C2H5OH or EtOH) is released; one molecule of ethyl alcohol being liberated for each ethoxy group that is hydrolyzed. These hydrolysis reactions occur stepwise, and the —OEt groups react in a statistically 11 l 0 ,1-1-;4 random fashion. e 0-s• % The general features of the sequence of reac- i‘ Si_ SeO S~ 0' t Si 0 tions are summarized in the following equations: 0 0 . 0 fvm Monomeric Species: frrer rrrl (Et0),Si + OH .> (Et0)3SiO "w rrt + EtOH (Et0)4Si + H2O —> (EtO)3SiOH + EtOH (Et0)3SiOH + H2O —> (Et0)2Si(OH)2 + EtOH RSi(OEt)3 + H2O —> RSi(OEt)20H + EtOH RSi(OEt)20H + H2O -+ RSi(OEt)2(OH)2 + EtOH Figure 1. Illustrating the molecular mechanism by which two particles of clay are cross-linked through the hydrolysis and condensation of ethyl silicate. etc. etc.

78 Condensed Species: Taking into account the composition of the Wacker (Et0)3Si-O-Si(OEt)3+1120 —> (Et0)3Si-O-Si(OEt)20H+Et0H H formulation used in the present work, we calculate ( Et° )3Si-O-Si(OEt )20H + Hp_.>H0( Et0 )2Si-O-Si(OEt )20H + Et0H that complete hydrolysis of 1 gram of this material would yield 0.71 grams of ethyl alcohol, and no ethoxy content would, of course, be left in the solid. Hydrolysis to the stage of the linear polymers etc. etc. shown in Figure 1, i.e., diethoxysiloxane from the Measurement of the total amount of ethyl alcohol tetraethoxysilane, plus methyl ethoxysiloxane from the released (or, alternatively, of the residual quantity of methyl triethoxysilane, would yield 0.40 grams of ethyl ethoxy groups) during the curing or aging of the alcohol for every gram of the Wacker H formulation, tmpregnant is thus an indication of the degree to which and the ethoxy content left in the solid would cor- hydrolysis has occurred. That is, if an average of only respond to 0.31 grams of alcohol. one of the ethoxy groups of each silicon ester molecule Hence, analysis for released alcohol, or for re- has been hydrolyzed, there would be observed one sidual ethoxy content, can show the average composition mole of ethyl alcohol per gram atom of silicon. If the of the silicon — containing metal-organic products pres- hardening effect involves the formation of long polymer ent in the stone— either immediately after the initial chains of diethoxysiloxane, such as that depicted in cure, or at any subsequent time. If such analyses show Figure 1, the molar quantity of ethyl alcohol liberated no change in composition with time, the impregnated would be close to 2.0 X the molar quantity of silicon stone may be considered to be stable. If the compo- ester originally introduced into the stone. sition changes with the age of the impregnation, this If substantially all the ethoxy groups have been may be a cause for concern (though not necessarily, hydrolyzed, the silicon-containing species remaining in as will be discussed later). the stone would consist of silicic acid, Si (OH)4, and its polymers (the end product of the dehydration of these polymers is silica or quartz, Si02) ; CH3Si (OH)3 C. Method of Determination of Residual and its polymers; and various condensation polymers, Ethoxy Content such as that shown in Figure 2. In this case, the molar A convenient and reliable method of determining quantity of ethyl alcohol released would be 4X the the ethoxy content of a specimen consists in fully tetraethoxysilane content, plus 3X the methyl triethoxy- hydrolyzing those groups, and recovering the resulting silane. liberated ethyl alcohol. Our procedure is as follows. The quantity taken of the substance to be ana- lyzed should be such as to contain not less than 1 gram of the silicon ester or its equivalent in hydrolysis and condensation products. For the proportions of reagent, 0--s!I 1si ,o,( e o x `o,% Si. % o dimensions of apparatus, etc., we employ, the sample, r0 C.i o -•••.,si, -,_,--- 's if a liquid should not contain more than 10 grams of 0 o o 0 , silicon ester; if a solid, such as impregnated stone, the r x r sample weight should not exceed 50 grams. x OH The weighed sample is placed in a 500-ml single- neck flask; 50 ml of 9 M H2SO4 are added; and the flask is tightly stoppered. If impregnated stone is being analyzed, it is first reduced to a fine powder. The Figure 2. Molecular structure of a possible product of the Hydroly- mixture is allowed to stand, with occasional swirling to sis of all the ethoxy groups from a silicon ester consoliclant. Note mix the contents and insure contact of the acid with that two —OH groups on the same atom tend to undergo dehy- dration reactions. all solid particles, for at least 6 hours. If much alkyl

79 alkoxysilane is present, the acid will not wet the sample that after the initial 3 + 1 day curing period, the easily, and the mixture should stand for one or more average degree of hydrolysis of the silicon esters was days to permit the acid to break through the hydro- 1.14 ± 0.05 molecules of ethyl alcohol released per phobic barrier. Si atom. When it appears that the sample has been Since this is an average, it means that there is a thoroughly wetted by the acid, and has been kept thus distribution of hydrolyzed species, including large pro- for at least 6 hours with occasional mixing, the flask is portions of those with only one or two ethoxy groups connected by a short adapter to an efficient condenser, reacted per original molecule. This shows that the initial and the ethyl alcohol is distilled over into a suitable consolidation effect is due to the formation of mostly receiver, e.g., a 20-ml graduated flask. Glassware with short siloxane chains, i.e., oligomers, rather than long- close-fitting ground glass joints is used for all set-ups. chain polymers. The temperature of the distilling flask vapors is In addition, it shows that after the initial curing monitored, and the condensate is collected until the the consolidant still retains intact a substantial pro- still head vapor temperature is 110°C. Under these portion of its original ethoxy groups. Thus, the initial conditions, the condensate contains substantially all of consolidation is produced by that portion of the silicon the ethyl alcohol, plus some water. Its weight is ester molecules that have hydrolyzed and condensed measured, and its alcohol content determined by into ethoxysiloxane chains of the type shown in Figure measuring the refractive index (nH2O = 1.334; nEt0H = 1 (and not into those of the type shown in Figure 2). 1.361; mixtures interpolate linearly in terms of weight 2. The analysis based on weight loss was checked by percent). In this fashion, a quantity of ethyl alcohol analyzing the 3 + 1 day cured specimen for its residual as small as 0.1 gram can be estimated with a precision ethoxy content, employing the H2S0, hydrolysis and of ±0.02 gram. distillation procedure described in Section C above. Using the data of Section D.1., the theoretical amount of ethyl alcohol that should be recoverable from the D. Experimental Results partially hydrolyzed silicon ester mixture in the mud- 1. The untreated Teleilat Ghassul mudbrick was allowed brick specimen is 0.77 grams per l gram of the cured to absorb the undiluted Wacker H solution by capillarity. impregnant. The actual amount recovered was 0.66 ± When substantially saturated (taken to be after about 0.08. This appears to be reasonably satisfactory a- 2 hours of imbibition) its weight had increased by greement. 17.2%. It was wrapped in aluminum foil and allowed 3. A sample of the Teleilat Ghassul mudbrick that had to cure for 3 days. The Al foil was then removed and been impregnated with the Wacker H formulation in the specimen was allowed to airdry for 1 day. At the 1979 by the same technique employed with the specimen end of this period, the weight of the specimen was of Sections D.1 and D.2 above, was analyzed for its found to be 10.7% more than before the impregnation; ethoxy content. From 14.20 grams of the solid, a total i.e., the imbibed material had decreased in weight by of 0.76 grams of ethyl alcohol was recovered. 37.8%. This weight loss is due to the evaporation of the The formulation employed in 1979 had one-half the solvent plus the ethyl alcohol that had been produced silicon ester content of the solution used for the by the reaction of the silicon esters with —OH groups analyses of Sections D.1 and D.2. If it is assumed that in the solid during the curing period. this specimen had absorbed the same proportion of the Correcting for the proportion of solvent, this weight solution as the reference sample, and that the initial loss corresponds to the release of 0.27 grams of ethyl degree of hydrolysis and condensation was also the alcohol per original gram of mixed silicon esters. same, then the 4-year-old specimen should have pro- Calculations based on the proportions of the several duced, upon complete hydrolysis by H2SO4, an ethyl silicon esters in the original consolidant solution, and alcohol yield of 0.5 (14.20/23.29) (0.77) , or the equiva- the stoichiometry of the reactions, lead to the result lent of 0.23 grams per gram of silicon ester oligomers.

80 The actual amount of ethyl alcohol recovered was 0.11 would occur with impregnated stone, but we do not grams from the equivalent of 1 gram of silicone ester have any objective evidence on this score. That is. it oligomers assumed to have been originally present i.e., is not yet known whether this phenomenon occurs also less than half the theoretical amount if no hydrolysis when the oligomers have been formed in the inter- had occurred after the initial cure. granular spaces of a stone or mudbrick. There is reason to believe, however, that if the E. Conclusions consolidating effect weakens and dissipates upon pro- longed aging, due to the ongoing hydrolytic reactions. The experimental data show that the consoli- the residue left in the stone will not interfere with a dating and strengthening effect produced initially by re-introduction of silicon esters to regain the consoli- he silicon esters in Teleilat Ghassul mudbrick involve ► dant effect. formation of oligomers that have a large proportion One caveat should be stated: it is not yet known of potentially reactive ethoxy groups still present. whether or not stresses are generated in a stone as A 4-year-old specimen that had been stored in a the initially formed oligomers undergo further re- normal indoor environment has a smaller ethoxy content actions. It is known that the increase in degree of than is expected based on the analysis of freshly hydrolysis is accompanied by a decrease in volume of treated brick. This indicates that hydrolysis continues the xiloxane moiety. to occur during long-term aging; it also shows that the The present investigation is, therefore, only a reaction is quite slow. preliminary exploration of questions that are of prime An estimate of the time required for the hydroly- concern for the long-term safety and stability of silicon- sis to be complete, e.g., to reach the stage shown in ester-impregnated solids. An appropriate analytical Figure 2, cannot be given at this time with much procedure has been developed, and some insights into confidence, because of the assumptions that would have the hydrolysis and condensation behaviour of a particu- to be made (e.g., that the rate of reaction is constant, lar silicon ester mixture have been gained. Further independent of the degree of hydrolysis and conden- studies are needed with other types of stone and mud- sation; also, that the initial reaction is not sensitive to brick, and over additional aging periods. the solvent concentration; etc.). It does appear, how- ever, that the degree of hydrolysis probably does not change much during the first several years of aging. References Furthermore, it is not yet clear whether the slow, 1. P.M. Schawartzbainn, C.S. Silver, and C. Wheatley, "The progressive increase in the degree of hydrolysis during Conservation of a Chalcolithic Mural Painting on Mud Brick from aging will necessarily result in a loss of the consoli- the Site of Teleilat Ghassul, Jordan", Third International Sympo- dating and strengthening effect. The glassy stage of sium on Mudhrick (Adobe) Preservation, 29 Sept. — 4 Oct., 1980, (2) , which is the form Ankara, ICOMOS, pp. 177-200. condensation of silicon esters S.Z. Lewin, "The Current State of the Art. in the Use of ill 2. present in the initially cured liquid, as carried out Synthetic Materials for Stone Conservation. Part. I. Inorganic and vitro in the laboratory, gradually crumbles to a fine Metal-Organic Compounds", International Symposium on Resto- powder as the hydrolysis reactions continue on toward ration and Conservation of Cultural Properties in the Open, 30 completion. It might be assumed that something similar Aug — 2 Sept., 1983, Belo Horizonte, Brasil.

81

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- -; ',' i't : Conservation of Structures and Adobe Decorative Elements in Chan Chan

Ricardo Morales Gamarra

This paper analyzes the conservation problems We divide them into two groups: intrinsic causes related to the structures and high-relief ornaments in (geo-topographic situation, nature of the soil and in- the archaeological complex of Chan Chan (X I Ith-XVth herent defects in construction) and extrinsic ones centuries A.D.) located near Trujillo, in La Libertad, (climate, physical and chemical phenomena, etc.). We Peru. do not include socio-economic factors, for we concen- For a better understanding of the topic, we deal trate on technical aspects. One should bear in mind with the causes of alteration, the building techniques that these causes are all interrelated. and how reliefs were made, the criteria used in resto- The alluvial terrace presents the following ration and the treatment applied. characteristics: slight orographic inclination (10 to 15 m. above sea-level); high salinity (over 7.5 pH) soil texture varying from sandy to very sandy; good electri- cal conductivity, high phreatic level (2.60 metres/ Causes of Alteration average) and proximity to the sea (1,000 metres, ap- We will examine here the causes of alteration proximately). specific to Chan Chan, which occupies 18 sq. kilometres. As additional information, it is interesting to

83 note that the lands south of Chan Chan were known stand the mechanics of what affects the adobes and in the last century as "Los Gramadales", because to give the necessary solutions. The joint action of gramalote (Panicum purpurescens) grew abundantly in these phenomena ("weathering") causes serious dam- them. This plant needs humid soil and does not tolerate age in the structures. Nocturnal moisture softens the prolonged dryness. In sum, the soil is humid, saline and surface of the bricks and activates the salts; insolation has little clay. If we add that it is generally agreed causes contraction, due to sudden drying of the surface that the adobes were made with materials found in the and produces saline efflorescence. Wind brings salts area, we can understand why chlorides and other salts in suspension (sodium chlorides) as well as sand from are found, in varying percentages, in most bricks. These the ocean; thus it becomes a highly erosive element salts are activated by humidity and by the salts in which also destroys the loose crusts in the upper part suspension brought in from the ocean by the wind. It of the walls. Finally, rain washes out surfaces, due to is thus important to recognize the negative action of the fragility of clay; it increases the weight of pro- the climate; this constitutes the most dynamic factor in jecting decorations, causing their collapse and forms all the degradation cycle. pools that seep into the foundations, causing the The climate in Chan Chan does not correspond collapse of walls and the loosening of the reliefs. to its geographic location: the cold of the Humboldt current bring a modification to the climate For these climatic reasons, we reached the con- and of the north coast of Peru. Thus, summer clusion that consolidation work should not be carried is warm, with little or no rain and dry, while winter is out between July and November, especially because of temperate, misty and with a special type of rainfall. the humidity and the activity of salts. We also concluded that roofs and covering are not an integral answer to When the warm waters of the "El Nitio" current appear, the climate is substantially altered. Tempera- the problem of rain, for the concentration of water in ture rises and remains high during several months, and specific areas requires appropriate drainage. To come rains are torrential. This causes serious floods, as was up with an adequate drainage system we must consider the case in 1983 and in previous years (1701; 1720; the underlying structures which we wish to conserve. 1728; 1858; 1891; 1925 and 1972). That is, the solution must include collateral actions. On the other hand, protective cappings also cause rapid Normally, temperatures are highest between January and March (27?C mean maximum). Relative hu- moistening and salinity in the top of the walls due to lack of sunshine. midity is the lowest (81 % mean maximum) and wind is predominantly S. and S.E. (1 1 mts./second, mean maxi- The permanent erosion caused by wind is helped mum). Rains are scarce and fall usually around Holy by the flat profile of the alluvial terrace. This is why Week. We do not have official data for rainfall; how- planting a protective barrier of trees (small, medium and tall) has been proposed. ever, we refer to Paul Coremans, who gives 38 mm. per year for Lima and somewhat higher for the north coast. This barrier would also indicate the start of the Zoltan Zsabo indicates an average of between 0.025 and Intangible Area and would help modify the climate. 50 mm. per year for the north coast of Peru. In 1983, We will now discuss some of the dangers caused the hours of rain totalled 36; the rainfall of 12 April by salinity in Chan Chan. (These are the conclusions of a test carried out by Miss Noemf Rosario Chirinos, a lasted 55 minutes and averaged 7 mm. chemist working for the INC). Between July and September, temperatures are the lowest (14?C is the mean minimum). Relative humidity Samples were taken from Ciudadela Tschudi. is the highest (86% monthly mean); wind is predomi- Eleven came from Temple N? 8, oriented towards the ocean. The average for chlorides here is 0.84% and nantly S. and S.E.E. (12 mts./second, maximum mean). for sulfates 0.79%. The second samples were taken Rainfall is almost absent — there is a type of fine mist called "gartia". from the Temple known as "Pelicanos Estilizados", located with its back to the ocean. The following re- This climatological information is basic to under- sults were obtained:

84 the sides of the adobes; there are empty spaces (of Samples Head of Salts Adobe Plastering the Wall varying width) between the bricks. This allows a certain elasticity during earthquakes. However, we must recog- Chlorides 0.21% 0.22°% 0.54% nize that this type of structures also allows rainwater 0.09% 0.04% Sulfates 0.05% to filtrate, causing crumbling or dripping of the mud. The perimetric walls have a trapezoidal shape This gives us two well-defined situations: 1) The — some are as high as 12 metres. The inside walls are location of the structures in regard to the sea and smaller and have geometric designs, such as lozenges wind determines the concentration of salts, which varies or chess-board patterns. In this last case, reeds or according to the height and movement of the under- other vegetable materials are used for horizontal sup- ground water (phreatic level); 2) The concentration port. Their decay, due to insects and to the excess of sulfates is equal or higher than 0.1 %, which Muni weight of the mud having absorbed water, causes prob- Kendam gives as a minimum before considering them lems and loosens the adobes. damaging in adobe monuments. The plasterings and decorations are highly plas- tic — they contain an average of 18% clay (while in the adobes the percentage of clay is 12%). Building Methods and High-Reliefs These reliefs and decorations are made after plastering, taking advantage of the plasticity and Chimu architecture is characterized by the ex- malleability of the clay. Once the mortar is applied on clusive use of adobe and cotton as building materials. the plastering, the relief is shaped by excision; to Stone was also used for the large foundations and complete the ornamentation, incisions are then gravel mixed with clayey mud for the upper foundations. practiced on them. Finally, the surface is polished and This mix (gravel and mud) was used for the painted in different colours. large-type adobones, which we find in the tall outside walls (Ciudadela Rivero) or in the funerary chambers, where they function as lintels in the tombs. They are Technical Criteria Used trapezoidal in shape, which helps to place them in the Our intervention followed certain criteria; we structure. will list the most important ones: Adobes are predominantly rectangular in shape, although some trapezoidal ones exist. Their size depends a. Stop the factors of decay and consolidate the struc- on their location in the structure; that is, the larger tures. ones are placed in the lower parts of the walls and b. Avoid restoration which seeks formal repair of the the smaller ones on top. These adobes, in Kolata's monument or its scenographic reconstruction. opinion, maintain a certain proportion, between height c. Additions are justified only for reasons of structural and width in any of the sizes. This researcher adds stability, distribution of rainwater at the top of the valuable information: when adobes were made, different walls, reinforcement or protection. forms or molds were used, including multiple-forms. d. The above requirements have to be satisfied prior Garbage was used in making them (as well as for filling to other considerations which take into account the in the structures). Evidently this suggests a certain tourist value or artistic aspect of the monument, for deficiency which, compounded with the use of saline these last considerations are both subjective and local earth makes these adobes more fragile than is controversial. usual. e. The relativeness of the concept of "reversibility" Adobes are placed on the wall in a way that must be considered, due to the nature and treatment specialists have recognized as seismo-resistant; that is of adobe. In the case of adobe, many products are one row is placed head down the next facewise. It is irreversibly applied, because of the mechanics of the interesting to note that the mud mortar does not join applications itself.

85 Restoration Treatment Chiari was soil-cement (earth-sand-cement). But con- sidering the salinity, humidity and the incompatibility We believe that, in principle, there is a technical of this material with saline earth, we decided —as an order to be followed when treating a structure. This alternative— on the use of lime. Subsequently we order may change, according to priorities which depend added to this lime-soil solutions of Primal AC-33 (acrylic on its condition. Isolated intervention, in any of these emulsion) at 10 and 20% in water, trying to find a stages, does not guarantee integral results. The order better formula against weathering. —in our judgement — should be as follows: We took into account the cost and the apparent a. Structural reinforcement. rigidity of this method, and proceeded to carry out b. Protection of the top part of the walls. tests using three types of sand and earth mixtures (2: c. Consolidation of plasterings and reliefs, as well as 1; 2.5: 1; 3: 1 vols.). We added lime to some and cement fixation of the colour. to others, in percentages of 2.5; 5; 7.5; 10; 15; 20:. The d. Total drainage. criteria for evaluation were: colour, endurance against Structural reinforcement has been directed, princi- drops of water and superficial hardness. The test which pally, to replacing missing adobes in the walls where gave the best results was lime at 10% in the three cases, there are holes, cracks or loss by crumbling. It also although the whitish colour produced was always a has meant changing adobes attacked by salinization problem. and putting in new ones, or re-using original adobes. We insisted on the use of plastic substances due In the case of the perimetric Tschudi wall, rows to the failure of soil-cement and the relative endurance of new adobes (reinforced with lime) have been placed of soil-lime in prolonged exposures. We needed a in the upper sections, to protect original adobes from stabilized capping whose endurance to weathering would weathering. justify the investment and would guarantee effective protection. In other cases, parts of decorated walls which At first, this capping was applied following the have slipped and are in danger of collapse have been original shape of the top of the walls; however, we placed elsewhere. Automobile jacks and mud mortar observed, during some rains, that there were difficulties, were used to secure them. in the distribution of the water and that the danger The use of wooden keys (using carob or similar of gullies subsisted, due to the intensity of the rains wood) has had good results for consolidation and which surpassed the capacity of absorption of the reinforcement of crumbling areas. capping. One of the most critical questions in the conser- This led us to find another solution: to incline vation of adobe archaeological monuments is the pro- the top of the wall towards the side of the wall with tection of the top part of the walls. Interventions seek no decoration. Evidently this alters the look which we to avoid loss of height of the wall, as well as drippings were accustomed to see, but it does not imply a formal and which affect both the reliefs and plaster- reconstruction of the treated area. ings and the structural stability of the walls, due to This solution was applied in the area of "Ara- rainwater filtration through the cracks. bescos", Ciudadela Gran Chimu. The heavy rains of Experiments in restoration, following this treat- the summer of 1983 supported our thesis. The reliefs ment, were begun only in 1977 in the area known as in the first sector did not suffer at all, while a stylized "Ciudadela Tschudi". Several UNESCO experts, among pelican in the second sector was affected by the gullies them Giacomo Chiari, Rodolfo Vallin and Jose Maria Ca- formed. brera provided suggestions and valuable advice for this We did not use lime in these tappings: the mix experimental project. used was coarse sand and earth (2:1 vol.) and poly- The main idea was to apply a stabilized capping vinylic acetate at 5% in water. in these areas. The type of mortar suggested by Mr. Capping should be applied following these steps:

86 A series of tests have been carried out, namely a. Elimination of superficial crusts and of humid-saline earth found under them. the application of chemical substances of a plastic b. Filling of cracks and holes with an earth-sand mortar nature on the surfaces of plasterings, reliefs and even (1:2 vol.). on the adobes themselves. The products used were: c. Consolidation of adobes, using Mowilith DM-1H at Primal AC-33 (acrylic emulsion); Mowilith DM-1 H (po- 5% in water, after having wetted the area with water- lyvinylic acetate); Paraloid B-72 (copolymerous acrylic); alcohol (1:1 vol.). Bedacryl 122 X (metracrilate) ; Calaton CB (soluble d. Addition of adobes (new or old) to form a slant or nylon). These solutions have not, had the desired results, inclination at the top of the wall, leading away from although the percentages used were very low (5% maxi- the decorated side. mum). After two years, we find cases of exfoliation, due to the humidity contained in the structure or In the case of walls having decorations on either because of the orientation in regards to the ocean. side, a concave roof covering was made with cane. This Moreover, the plastic film formed makes future ap- permitted the water to flow towards a ramp, built next plications difficult. to the structure. These elements are totally reversible, However, the adhesive action on the plastering, as is the capping. This solution was suggested by Ismael as well as between the plastering and the supporting Perez. wall (that is, its application in depth) presents no ex- e. Application of a mortar of coarse sand and earth foliation problems. (2:1 vol.). The cracks caused by drying will help the We have used, with good results, ethyl silicate stabilized capping to adhere better. 40, combined with ethyl alcohol at 96% and hydrochloric f. Use of the stabilized capping, as mentioned. This mix acid. Giacomo Chiari first introduced this treatment in must not be too watery, to avoid cracks. The first layer Peru in 1975 and we have followed his steps. Appli- must be applied with a spatula, for better adherence. cation of this substance, however, still leaves some and then the hand should be used, to avoid surfaces specialists skeptical, due to its irreversible character with too much polish. and the fact that it causes structural alteration of the The torrential rains of 1983 have shown us two adobe. However, considering the results obtained, we things: first, the strength of the capping, its ability to believe that —to the present — this product is the most absorb water and to dry without cracking; second: that appropriate one, due to its waterproofing capacity as there is a critical problem in its adherence to the wall. well as because it gives good consistency to adobe and Because the wall is not located with a waterproofing produces minimal alteration of its colour. consolidant, it is affected by water. Thus, we believe To give an idea of its waterproofing capacity and it necessary to use a silicate, or a similar product. consistency, we will report a simple test. We plunged A second aspect in the conservation of Chan Chan two specimens of reliefs in water, one untreated and is the treatment of plasterings and high-reliefs. The the other consolidated by immersion, with ethyl silicate exceptional aesthetic quality and the testimonial char- 40. After ten minutes, the first was totally destroyed, acter of these decorations conditions all restoration keeping only the superficial crust. The second specimen action, for the treatment of the plasterings and deco- endured four hours, unaltered. It was then placed at rations is linked to the supporting structures. a temperature of 52°C (it dried in sixteen minutes) This link between support and relief-decoration and then was immersed four more hours. It showed no conditions the treatments applied at the following signs of alteration after this treatment. levels: Certain requirements have to be met when ap- plying ethyl silicate: a. Consolidation of the clayey structure of the plastering must be 96%. and relief-decoration. a. Quality of the ethyl alcohol: it b. Adherence of the plastering to the wall. b. Wind or air currents which accelerate the normal c. Adherence of the relief to the plastering. evaporation of alcohol must be avoided. Evaporation

87 is slowed down by covering the area with plastic, for planes which carry the rainwater towards them. a period of 5 to 7 days. 2. Drainage is the immediate and necessary solution c. A high degree of humidity (both contained and for Chan Chan and similar monuments. atmospheric) must be avoided, for it impedes polymeri- 3. Protection for the top of the walls should be done zation of the consolidant. using capping whose structure does not differ from the d. The surface to be treated must be cleaned of any walls they protect. These cappings require permanent particles adhered to it, as well as of dust. Cleaning maintenance. must be thorough and should respect original forms. 4. Consolidation tests clearly show the advantages of Faced with the problem of adhesion between using ethyl silicate 40 over all other plastic materials. the plastering and the wall, and between the relief 5. It is necessary to set up an Emergency Project, where and the plastering (which is not solved by this product) priority actions be established according to the types we decided on the use of Mowilith DM-1H or Primal of natural disasters. AC-33 at 3 or 5% in water, as we have previously explained. The voids or pockets which are eventually formed between these layers are filled in with aqueous Suggestions mixed of earth and fine sand (1:2 vol.) and lime at 1. To set up a Regional Project for the Peruvian North 10%. Naturally, the area to be treated is first wetted. Coast, where norms would be established and carried The solution, thus, was found in the use of a out for the protection of archaeological adobe monu- mixed technique: silicate and polyvinylic acetate. ments during rainy seasons against flooding and other Finally, we drained the Temple of the Arco Iris natural disasters. (Rainbow) using PVC tubes 4" in diameter. This pipe 2. To seek the participation of international organi- system was connected to the fourteen enclosed deposits zations, such as the OAS, UNDP and others, as well which surround the central structure; at the centre of as the Peruvian Government, to establish the a- each enclosed area a was built. Two other forementioned Regional Project for the Protection of were placed in the lower part of the inside the Adobe Archaeological Heritage. corridor, to collect the rainwater and drain it to two 3. To establish in Chan Chan a Research Project for its other reservoirs, with a capacity of 12 m' each, placed conservation. 10 metres away from the perimetric wall. The tains. however, surpassed the capacity of the reservoirs. These measures prevented flooding in the reliefs and Bibliography structures; this is extremely important, for this monu- ment, we must remember, lacks foundations. CABRERA GARRIDO, José María, "Informe técnico". We have examined, in this paper, the more im- UNESCO, Cusco, 1977. COREMANS, Paul, "La Preservation du Patrimoine Culturel du portant aspects of the conservation of adobe in Chan Pérou". Misión UNESCO, mars-avril, 1964. Chan. This work has been carried out by a team of CHIARI, Ciacomo, "Informe técnico de trabajos en Chan Chan". restorers and archaeologists since 1974. Our thanks to Presentado al INC-Trujillo, 1977. Carlos Castañeda, Carlos del Mar, Héctor Suárez, Ana MORALES, Ricardo, "Informe técnico del Proyecto Piloto de María Hoyle and to the Director of the Restoration Conservación del Adobe". Trujillo, 1977. Centre, Cristóbal Campana. MASSARI, Giovanni, "Humidity in Monuments, Roma, Inter- national Center for Conservation", 1977. RAVINES, Rogger, "Chan Chan, metrópoli Chimú". Lima. Insti- tuto de Estudios Peruanos, 1980. Tecnología andina. Lima, Instituto de Estudios Peruanos, 1978. Conclusions SANPAOLESI, Piero, "Cause de détérioration des monuments", 1. It is urgent to take measures to protect the base in: La conservation et la restauration des monuments et des bâtiments historiques. and lower part of the wall in order to avoid inclined París, UNESCO, 1973. STAMBOLOV, J.R.J. Van Asparen de Boer, "The Deterioration 88 and Conservation of Porous Building Materials in Monuments". Brick Preservation'', in: Estratto de Mesopotamia (Revista di Roma, 1972. Archaeologia, Epigrafia e Storia Orientate Antica). Torino, G. SZABO, Zoltan, "The Conservation of Adobe Walls Decorated Ciappichaelli Editore, 1972. with Mural Paintings and Reliefs in Peru". Zagreb, 5th Triennial VALLIN, Rodolfo, "Informe Tecnico de Trabajos en Chan Chan". Meeting ICOM, 1978. Lima CIRB, 1975-76. TORRACA, Giorgo, "Informe Tecnico". Mision UNESCO, Cusco, WINCKLER, E.M. — CLIFTON, J.R. "Solvents for Adobe and 1978, Stone Preservatives" in UNESCO-RIEEM, Colloque International. TORRACA, G. — CHIARI, G. — CULLINI, G. "Report on Mud- Paris, Junio 5-9, 1978.

89 t4441. 44Witt Alteksa .41st

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Iowa: pat 'yt-14.- :. . 14 if it41..t' eviv%$ trvistet ;tf,... 1141:- 41141444 Prio50! - 'la* -Alio& .w14101 oft --4*,e41001,itt A Survey of the Painted Mud Viharas of Sri Lanka Ashley De Vos

The Island of Sri Lanka, an Independent Republic The construction technology of the buildings in located South of the Indian Land mass, is predominantly a typical temple complex consisting of the temple (vihara, Buddhist. It has a well documented and written history pilimage) bo-tree and platform (bodhi maluwa), the of over 2200 years and a civilization extending dome-shaped monument enshrining sacred relics (da- much further into time. Sri Lanka is not affected by goba, stupa) preaching hall (bana maduwa) and the earthquakes or cyclones but is subjected to four months residences of the monks (pansala) leaned heavily on of annual rain and an 80% humidity. It is, therefore, that of the simple village dwelling for methodology a country possessing an aggressive vegetation and tropi- and style. cal climate. The dwellings in the villages were basic and built Life in a typical Sri Lankan village revolved of material extracted from the immediate environment. around the temple, its focal point. The temple was the Mud being readily available in a variety of compositions school, the community centre, •the council and refuge. and qualities dominated this technology. Six basic Sri Lanka can still boast of about 2500 such temples of construction techniques were used, namely, different shapes and sizes scattered around the coun- a. Wattle and Daub (Varichchi) try in varying conditions of construction, maintenance or decay. b. Cob (Undi)

91 c. Adobe (Mordegal) external face of the rock. The donor's name was at d. (Thappa Bammi) times carved on the face of this ledge. Immediately e. Stone walling in Mud (Sakka Bammi) below this ledge, a timber framed, terra-cotta tiled, f. Laterite block (Cabook) lean-to roof supported on carved wooden pillars or (along the western coast line) stone columns (kuluna) with wooden brackets (pekada) formed a protected walkway or verandah (pilla) . A The vertical surfaces of the buildings were pro- thick wall with one or more doors and windows sepa- tected from rain erosion by constructing roofs with rated this verandah from the inner in which the wide eaves. image or images were placed. The viharas are of two basic types, the cave This wall was made of mud carefully smoothed. temples (gal viharas) and temples built on pillars or plastered and covered with paintings of the latakas platforms, the structural temples. (stories on the lives of the Buddha) or other significant a. The cave temples, consist of natural caves, specially events. The ceiling of the cave was levelled and sized prepared with a drip ledge (kataraya) cut around by covering it with a layer of finely ground sand and the mouth of the cave. This ledge protected the interior clay mixed with water. This surface was further of the cave from rain water runoff flowing down the prepared before painting.

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92 b. The structural viharas, like the village dwellings are inner wall, made of mud, plastered smooth and painted raised higher than the surrounding ground. They are is afforded protection from the elements by the veran- either built on: dah and wide eaves that encircles it. In the hill country, the viharas are often built on top 1. Short stone columns of rock outcrops. These temples stand out in the 2. On boulders environment and form focal points in the landscape. 3. On high plinth: or The walls are often made of stone set in mud, plastered 4. On bare rock outcrops and painted. In other areas high terraces of stone and The viharas on short stone columns (Tampita Viharas) mud are constructed on which the viharas are placed. or on boulders are reminiscent of the mud These viharas are at times two-storeyed. They are (bihi) or paddy storage bins in the village that are capped with timber framed, terra-cotta tiled roofs with raised in a similar fashion as a protection against wide eaves to protect the mud walls below. The upper termites (white ants) or rising damp. These temples floors are made of timber boards supported on timber consist of a single rectangular or square image house, sub-frames. covered by a timber framed, double slopped terra cotta tiled roof. The outer part of the roof shelters the Location of Painted Surfaces open verandah, that encircles the image house. The Most walls of the viharas are covered with paintings of the Jataka Stories, in long, narrow, con- tinuous panels. This visual narration is at times inter- spaced with an explanatory note. In the majority of the temples, the paintings are limited to the inner face of the shrines. However, examples of viharas with the external faces painted do exist. The decision to paint a particular wall is not governed by a convention but rather by a decision dictated by time and place. In addition mouldings, pilasters and ceilings were also painted. The areas inbetween were filled up with V1HARA- EXTERNAL. CORR/DOR EITHER designs to create a continuity of painted surface. The TIMBER COLUMNS OR MASONARY , /IUD statues of the various deities were first framed in WALLS ENCLOS/NG MA/A/ SHRINE timber, moulded in mud, plastered, painted and placed in their order of importance at the entrances to the shrines. The statues in the inner chamber of the shrine had a core of stone, brick or timber, completely moulded in mud and were carefully plastered and painted.

Methodology The wall surface was carefully prepared by first plastering the mud wall with a layer of finely ground clay and sand. Clay from termite mounds was ideally suited for the purpose. It was then covered with a thin layer of kaolin (kirimati) made very smooth and VIHARA - TWO STORIES. IMAGE HOUSE ON UPPER FLOOR PREACHING HALL compact by rubbing with a metal or . This (.6teznet .1.1crae...,ra) ON GROUND FLOOR. was finally covered with a coat of magnesite (makulu) .

93 The outline of the painting was then executed on schedules have changed, in that concrete is used this pure white surface using a fine brush made of teli to repair mud. Cheap, glossy oil paints have replaced tana grass (aristida adscensions) and black paint. the traditional paint , all culminating in de- Brushes made of squirrel's hair for fine work, struction rather than preservation of the temples. and those made out of the root of the Pandanus The temples, traditionally lighted with oil lamps, (vetakeyiya) were used for filling up the spaces are today fitted with electric lamps in an effort to between the figures. This back ground was executed exhibit the paintings to 'tourists'. The crude fixings of in a technique using layers of two to three coats of the light fittings with wires trailing across the painted pink and red , until the final intensity of the surfaces are a common sight. required red background was reached. The temples of the East are objects of a living The materials used in the manufacture of the vari- religion as opposed to the Museum attitudes in the ous colours were first gathered and carefully ground West. The dark, limitless spaces are used for meditation, into a fine powder using a stone mortar. This powder but today the electric lights add a theatrical quality to was mixed with gum (divul latu) from the elephant these simple spaces. Suddenly the boundaries are visi- apple tree (feronia elephantum) and water to form a ble. The lights have displayed paintings hitherto un- paste. The paintings were executed using a tempera seen, but the exposure to excessive light has started a technique. The paintings in exposed situations were new type of decay from exposure to radiation, leading done using the oil from the Dorana Tree (Dipterocapus to the fading of the colours. These lighted temples Glandulosus). attract more visitors, thereby increasing the humidity The painters painted traditional themes in a levels, which in turn causes the paint film to peel off. traditional style, drawing inspiration from scenes and The large numbers of visitors have destroyed the objects in their particular contemporary environments. sanctity of the interiors of the shrines. Guides tramp These paintings today are a window into the History across sacred boundaries dragging behind them gaggles of the times. Their visual narration make them more of tourists, like geese trouping across pasture land on accurate than any history book. The scenario unveils their way to the water. exactly how the people lived at the particular period Traditionally, windows were provided for both the paintings were executed. The architecture, fashions ventilation and light. The introduction of glazed pan- and designs, the transport systems, the food, the furni- els might keep out the bats, birds and maintain the ture, the foreign influences, the fauna and flora, etc., natural light levels, but destroys the effect of natural were all vividly portrayed on the walls. air movement through the structures, which is essential, for drying of the wall surfaces in the humid tropics.

Deterioration Factors Conservation and Conclusions This patrimony is subjected to a number of de- The causes of destruction are universal and so terioration factors both natural and caused by man. is the theory of conservation. Each country should That which is mancaused, namely neglect or lack of evolve a theory best suited for its aspirations, within the maintenance, is invariably the most serious. guidelines set out in the International Conventions. We In the past these temples were patronised and should not forget that all cultural property belongs maintained by the village. The temples were repaired to the Heritage of Man. It is our duty to preserve it and repainted on a regular basis by the temple societies for those who come after us. Our choice of methodology (Dayake Sabhas) using traditional techniques and meth- should be responsible and devoid of excessive experi- ods. Today, with education and the chase for material mentation. Traditional methodologies, which included wealth, the traditional protection devices have dis- careful and regular maintenance has preserved muc6h integrated. The population has less time, the material of this patrimony from the ravages of time.

94 This presupposes a need to re-acquire some of Bibliography this lost knowledge. The conscious study and the system- Wickremasinghe, Sinhalese Manuscripts in the British Museum. atic documentation of traditional technologies is of Coomaraswamy Ananda K, Mediaeval Sinhalese Art Pantheon prime importance. The most humble village is an unlimit- Books. ed fountain of knowledge. Many of the solutions to our Cave H. W., The Book of Ceylon — 1908. Cassell and Company Ltd. problems are available at grass-root levels. We must De Silva R. H., The Technique of Ancient Sinhalese Wall Paintings be humble enough to acquire them. We cannot always — Sigiri, Paranavitana Felicitation Volume — Colombo. pray to the Gods (UNESCO) to constantly send us De Vos Ashley, Some Aspects of Traditional Rural Housing and experts to solve our problems. We need to develop Domestic Technology — 1977. National Museum — Colombo. skills within our own countries; we need to communicate Mud as a Totally Viable Building Material — 1977. Architect in Development — Colombo. with each other. It is only then that the real meaning Restoration and Rehabilitation of Historic Houses — Possibilities of the Heritage of Man will emerge. and Attempts — 1982. Architect in Development — Colombo.

95

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4rftrf -f ' A reconstitution of the tower of Babel in Babylon. It is most probable that the huge tower dedicated to the god Marduk was ri/I the tower mentioned in the Bible. , _rr`rEr rr -rirrrri r1 c

Temple of Emah, Babylon, Iraq. Recon- struction.

97 Iran. Yazd. Domes on the roof of the bazaar.

98 Adobe building, Punjab, .

Ecuador. Rural adobe arquitecture.

99 ***t1t*Iikt*PrO"

100 Previous page: Adobe buildings, Mali.

Adobe and mud architecture. Mali.

The Mission Church at Tumacacori, New Mexico, USA after restoration. It is a Na- tional Monument today.

Using precise levelling equipment to detect foundation settlement at Tumacacori Natio- nal Monument.

k

The Masmak in Riyadh, Saudi Arabia. Around it the city loses its character and has become "westernized".

Tower inside the Masmak in Riyadh, Saudi Arabia before and after reconstruction in 1982.

101 Ruins of Chan-Chan, Trujillo, Peru: a view of the archaeological site after the heavy rains of March, 1982. Drainage is crucial to solve this problem.

Huaca del Dragon, Trujillo, Peru. Initial consolidation of the relief by injecting plastic substances.

102 Making adobes in Osak, Turkey.

103 Drying adobes in Iraq

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• __A /1•1,'44 Drying adobes in the Andean region.

Conical adobes are shaped by hand in Africa.

104 The mud is mixed with straw to strengthen the block. Making adobes in the Andean region.

Cers, France. Adobe and wood architecture. Notice in the lower part of the house the different techniques used for plastering.

105 Dr. Erder and Mr. Sylvio Mutal, Regional Coordinator of the UNDP/UNESCO Regio- nal Project on Cultural Heritage and Deve- lopment chat with the former President of Peru, Architect Fernando Belaunde Terry during the visit to the Government Palace.

Dr. Cevat Erder, Director of ICCROM, and tYlku Izmirligil from Turkey in Machu Two views of the work sessions during the Symposium. Picchu.

106 The participants visit Puruchuco, a pre- Columbian adobe monument outside of Li- ma.

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107 Giacomo Chiari (ICCROM, Seymour Z. Lewin ( USA) and Paul Schwartzbaum (ICCROM).

A group of participants in the Symposium during the visit to the National Museum of Anthropology and Archaeology, Lima.

108 Right: French Basque region. Earthen construction on the right- hand side of the street.

Legislative Palace, Tlaxcala, Mexico.

Convent of Tepeyanco, state of Tlaxcala, Mexico.

Below: Interior of the open chapel at Tizatlan, Tlaxcala.

109 Left: A typical 18th century house near Cusco. It is still used today as such, but lacks plumbing and other services.

Casa Vivanco, Ayacucho, Peru, restored by the Banco In- dustrial and now its headquarters in that city.

Hacienda-house, Buena Vista, Cusco.

Below: Determining changes in wall tilt by periodically measuring the distance between a plumb bob string and a permanent reference bracket.

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Ancient College of San Bernardo, Cusco, restored with support from Unesco. Today it is the seat of the National Institute of Culture in that city.

111 Left: Old convent of Sap Francisco, Santiago de Chile. Once restored, it houses a Museum.

Tower of the former Hacienda Mendoza in Rengo, Chile. Today it is the seat of a Benedictine Monastery for Women.

II I

'7 Below: Tower of the Church of La Merced, Rancagua, after 11111 -.. restoration.

1 1 2 Bamba, Senegal. Plastering with mud over adobe.

Malatya, Turkey. Contemporary adobe houses.

Experiments carried out at the Catholic University of Peru to achieve seismic- resistant adobe houses.

113 Fortress of Van, 12th century A.D. Adobe towers, Turkey.

114 ' - •411 • .

China. Turfan oasis. Central Yar Steppe. Siria. Inside of a house under construction. Mud frieze, Chan-Chan, Trujillo, Peru.

Next page: Convent in Tod, Egypt.

115 I lb Raw Earth Techniques (llanco') Used in Mali Nianti Bouare

I. Introduction The country is subject to the influence of two Mali is located in the heart of West Africa. It predominant winds: occupies an area of 1.240.710 square kilometres and —a dry wind (northern trade wind or harmattan), extends between 10° and 25° latitude north. The which blows from northeast to southwest during the dry Greenwich meridian crosses Gao. The country is land- season. locked and surrounded by Algeria to the north; —a humid, warm wind (the monsoon) which blows from to the east; Upper Volta, the Ivory Coast and Guinea the southeast to the northwest and which brings rain. to the south and Senegal and Mauritania to the west. Different climatic zones exist; going from north Bamako, the capital, is 1.272 km. from Dakar by railroad, to south these are: and 1.086 km. from the seaport of Abidjan by road. The country is located in the northern tropical —a tropical and humid zone, with a Sudanese climate, zone. Two seasons exist: the rainy season, going from which extends south of a line passing through Kayes June to September, and the dry one, extending from and Bandiagara. Annual rainfall varies between 1.350 October to May. mm. to the south and 800 mm. to the north. The average annual temperature varies ac- —a tropical arid zone, with a Sahelian climate, ex- cording to the latitude; towards the north, it is quite tending between this line and the parallel of Timbuktu, high. with an annual rainfall of between 600 and 250 mm.

117 The Saharian zone, extending north of the of ceremonies. The cult of the Gabibi is celebrated; parallel of Timbuktu, whose annual rainfall is under (that is, of the being possessing spiritual powers that 300 mm. confer grace) and a festive atmosphere exists as a According to the 1976 census, the country has a result of the help given by all the community to the population of 6.750.000. The district of Bamako and its person building his home. satellites (Kati, Kulikoro) has a population of 600.000. The building techniques and the material have There are 43 cities with over 5.000 inhabitants. remained almost invariable through the years. It would About 90% of the population works in the primary be desirable, however, that the necessary measures be sector (agriculture, fishing, cattle raising). taken for the good conservation of the old cities —among Historians agree that —as far back as one may them, Timbuktu. Teams of archaeologists should continue go in the history of humanity— the first civilization to excavate the historical buried sites and consecrate appeared on the banks of the Nile. themselves to the protection of those sites which have From this Egyptian civilization come the Proto- already been dug-up as well. Wangara, that is, the civilization of the soninkes situated in the border area between Senegal and Mali. The Sarakoles in Senegal and the Marakas in II. Building Materials Mali have inherited a knowledge thousands of years Mali has an enormous potential insofar as tra- old, and have transmitted it from generation to gene- ditional building materials are concerned. ration. (Cf.: Africa, Cradle of Civilizations and Black Throughout the country, clay, lime, sand, laterite, Civilization or Barbarism, by Cheich Anta Diop). etc. are found. In certain regions, also slate, schists This explains why the Sudanese — Sahelian style and marble exist. is found throughout this area in north and northeast West Africa. 1. Banco The trade between Black Africa and White Africa gave rise to cities in the crossroads of the caravan Banco is the most traditional building material and the routes. We will mention here only the oldest cities: one most commonly used in Mali. The use of this ma- Timbuktu, Djenne, Mopti and Gao were born of this terial makes Malian architecture extremely original and traffic and their layout, often radioconcentric, has a very well-known, both in Africa and world-wide. flexible texture. Banco pits are found all over the country; however, the chemical composition, as well as the physical and The building material used was always earth; mechanical qualities differ from one region to the next. often, the houses were two —and three— storeys high The rural habitat (over 90% of the total population lives and the thickness of the walls lessened as they grew in rural areas) is made of raw banco; the same is true higher. This gave the buildings a truncated-pyramid of the historical monuments which are the pride of Mali. look. The majority of these edificies are well con- served, thanks to the constant maintenance given to 2. Some Traditional Methods Used in the the important buildings, such as the and the Conservation of Raw 'Banco' large "bourgeois" homes. A large part of them, how- The rural populations, concerned with preserving their ever, has been destroyed by razzias, wars or other homes against the inclemency of the weather, have conflicts. developed certain methods for the conservation of The use of earth as a building material is deeply banco. Among them are the following: rooted in the soul of the Sudanese-Sahelian population, closely linked to the nourishing earth. —Stabilization using straw Construction of a building gives rise to a series This technique consists in mixing a certain proportion

118 of straw with bunco (this is known as "reinforced this, it is necessary to find a cheap basic binder. banco"). This stabilization method is used both in the This project, now in its third year, has established an making of the bricks and in plasterings. inventory of the existent typology of buildings in Mali. It has indicated the location of the different sources —Stabilization using oil of lime in the country, as well. This project will make it possible to obtain cheap In the south of the country there is a tree, called basic binders, by installing small artisanal lime ovens Karite, whose nuts produce oil. The inhabitants of this near the rural centres. region mix this oil with the banco to obtain a material In keeping with the concern to use banco as a fit resistant to rain. Generally, the plasterings are stabi- building material, Mali has initiated the construction of lized either with the oil or the residue of Karite nuts. some public buildings, such as the Health Centres. These — Stabilization using animal excrements buildings, financed by the African Development Bank (BAD) will be built by the ADAUA (Association for In many areas, earth is mixed with animal excrements the Development of an African Architecture and Urban to obtain a more resistant material against weathering. Planning). All these efforts undertaken by Mali, one of the —Stabilization by firing countries most severely touched by the drought, risk 1 n the regions of Mopti, Goundam and Dire, small fired being in vain if a solution is not found for the conser- bricks are made. These bricks are used to line the flat vation of raw banco. In effect, because of the already terrace-roofs. This method is unknown in regions with exorbitant cost of imported cement (1.100 French francs; abundant rainfall. about US$ 137 per ton) stabilization using cement, even in percentages of 5%, is no longer economical.

3. Actions Taken to Revalue the Use of Local Materials III. Research Structure Bamako, the capital of Mali is 1.000 km. away from a In almost all of the countries of West Africa, maritime port, as we have seen. research organizations have been set up. Among them Since 1973, as a consequence of the energy crisis, the we may mention the following: price of cement augmented noticeably. The Government —in Senegal: the School of Architecture and Urban of Mali at this time established a policy with a view Planning; the Research Centre for Habitat, Urban to revalue the use of local materials and to improve Planning and Architecture (CRHUA). traditional building techniques. —in Mali: the National Centre for Research and Experi- The National Centre for Research and Experimentation mentation for Construction and Public Works (CNREX- in Construction and Public Works (CNREX-BTP) was BTP); the Project of the Centre for Adapted Technology pits found asked to do a study on the different banco (CTA), which is funded by UNDP. in the diverse regions of Mali; this work was sollicited —in Togo: the Centre for Construction and Housing at by the Department of . Cacavelli, near Lome (CCL). The results of this study are to be found in a publi- —in the Ivory Coast: the Centre for Research, Archi- cation entitled: Studies on Stabilized Earth in Some tecture and Urban Planning. Regions of Mali. The most important research project in the field of An essay in sub-regionalization has been under- Banco is the one of the Centre for Adapted Technology taken by the Centre for Construction and Housing in (CTA), whose objective is to improve the living con- Togo. On a sub-regional level, mention should be made ditions of the poorer sectors of the population by of ADAUA in Ouagadougou, Upper Volta and the ENDA improving their traditional habitat. In order to achieve in Dakar, Senegal. 119 One of the problems that limits the use of banco It would be desirable that the international is that of roofing. There are some ongoing research organizations establish a set of specific norms for each projects to try to solve this problem. ADAUA has built, region, so that buildings made of banco might have the in Rosso, Mauritania, homes with a dome as a roof. In same access to bank loans as those built in concrete Mali, as well, the Agency for Cooperation and Equipment or cement mortars. (ACA, France) has experimented with straw roofs with Much has been done to the present, but unfortu- intercalated polyethylene sheets. Although one should nately information concerning banco has not been be careful in predicting the durability of these straw centralized. UNESCO, ICCROM or ICOMOS could take roofs, all these experiments should be fostered and up this task of centralizing and divulging all existing supported. information regarding banco.

120 The Protection and Conservation of the City of Tlaxcala, Mexico Gilberto Reyes Zepeda

During the Conquest, and as a result of the al- The city of Tlaxcala, the State capital, has 20,000 liance of the Spaniards and the Tlaxcaltec Culture, inhabitants and in its surroundings at least 80,000 more, were built, among other buildings, several open in villages and cities comprising five municipalities. chapels, which are characteristic of the first phase of Following the urban development plans and in the Conquest; as well as Franciscan monasteries in accordance with the decision taken both by the State the XV1th century and churches during the XVIIth, Government and the National Institute of Anthropology XVII Ith and XIXth centuries. and History to define an area — urban center, norms From the point of view of , several have been established to maintain the 400 year-old cities, such as Huamantla, Calpulalpan and the capital image of the city. Tlaxcala, are characterized because they have main- In the streets and urban locations, the solution tained practically the same urban image during the last has been to provide sidewalks suitable for the circu- 400 years. Specific measures for their preservation, lation of pedestrians with a row of trees and low and restoration plans for several buildings, both public bushes, as well as to maintain a harmony in the colour and private, have been taken with the basic objective of the facades within the same range of shades, of preserving the cities, their buildings and the existing varying from ochre to oxide red. and future urban image as a cultural heritage for the This same criterion has been applied in small inhabitants. towns and cities where common spaces like the Civic 121 Squares and meeting places have also been treated. spected, creating at the same time a luminous atmos- Special attention has been given to the recovery phere with an inner garden. and restoration of public buildings, of a historical The open chapel of Tizatlan was an interesting and cultural value. These buildings have a special restoration example; it was close to collapse and, while characteristic: all were built in adobe and a soft stone recovering the monument, two XVIth century frescoes called xalnene, which combined with adobe provided were also discovered. them with an adequate resistance. The convent of San Francisco in Tepeyanco, is One of the sites which has been preserved is also a XVIth century building, monumental in its the Monastery of San Francisco, a Xlth century complex construction and comprising an open chapel with five which has survived the centuries and consists of a big arcades with a double aisle, now under restoration. cathedral, monastery, walls and surrounding streets Another convent of the XVIth century, one more with buildings made of adobe and xalnene, including of the twelve existing in the State, is the Franciscan the bullring. convent of Atlihuetzia. This complex is spectacular also Another building is the State Art Gallery, origi- for its monumentality. The principal nave and the nally a private home. It was adapted respecting all convent in itself have lost the roof, but its main inner the spaces and recovering others already deteriorated. arcades, in the choir area, have been conserved. Its to serve as exhibition hall and paintings deposit. The walls are still standing, creating a space both pleasant straw loft was transformed into a small auditorium. and impressive. The Legislative Palace, located downtown, was What we have showed in this Symposium is part built at the end of the XVIth century and originally an of a State's effort, within a country like Mexico, where annex of the church, presently known as Parroquia both the inhabitants and government officials are de San Jose. During the last 30 years, this building trying to maintain, among other things, the historical operated as a hotel. The building was completely and cultural patrimony inherited from our ancestors. deteriorated, outside as well as inside, having lost its It is also their concern to leave to future generations original characteristics. Attempts were made, when witnesses of a country's cultural development. We hope restoring this building, to preserve the oldest walls; you will have the opportunity to visit us and enjoy inside, two arcades which are the most valuable elements these buildings in their original location and, above were found during this restoration. all, see them functioning, given that the basic criterion What originally was a school, built at the be- for their restoration and recovery has been daily use, ginning of this century, was adapted to serve as the which also supposes timely and preventive main- State General Archives. The original spaces were re- tainance.

122 Tumacacori National Monument Paul McHenry, Jr.

Other features of the monument include partial History remains of a , funeral chapel, service buildings The Tumacacori Mission, located approximately and a camposanto wall. The camposanto wall plaster 50 miles South of Tucson, AZ, the northern outpost of was decorated with red brick chips, original portions a mission chain constructed by Franciscan Priests in the of which still remain. Plastering techniques used made later 1700's. Its present form was completed and in use of locally available materials without the newer use about 1823. The principal structure is a church, portland cements and products used today. Until its designation as a National Monument in built mainly of adobe bricks with 6 ft. thick lower walls. The church building incorporated a single bell tower, 1908, the structure had been vandalized and looted a dome over the sanctuary, and a barrel vaulted for usable building materials. Since its acquisition, sacristy. Many ornamental features were done in low repeated efforts had been made at various times for fired (burned) adobes. restoration and stabilization. Many of these well meant Most of the wall surfaces were plastered with a efforts incorporated new types of building materials, lime/sand plaster, with the lime being located on i.e. asphalt stabilized adobe bricks colored cement the monument grounds. , plastic vapor barriers, various types of chemical 123 waterproof coatings and sealants. Some of these repairs locations not previously affected. The major task of created unwanted side effects, concentrating moisture the stabilization effort was to determine original mate- and accelerating deterioration. Moisture infiltration rials and techniques used, duplicate them, and evaluate from unknown sources in the massive nave walls was the results compared with more modern materials and of prime concern. methods. The methods evaluated would provide new information and guidelines for the maintainance of Design Criteria other earth monuments for which the National Park Service is responsible. The criteria established by the National Park Adobe test walls were built on the Monument Service was to stabilize and preserve the cultural grounds and subjected to various conditions and treat- resource rather than full restoration. First priority for ments. Extensive testing was perfomed by NPS labo- the project was to determine causes, stabilize the struc- ratories on soils used in existing historical walls and ture to prevent further deterioration, and to take no plaster, as well as repair materials proposed for use. steps that might have unforeseen consequences. The Adobe bricks were manufactured, using idealized soil first rule of preservation technology was to be followed, mixtures, as well as locally available soils. By laboratory do nothing that would be irreversible. standards, the local soils seemed unsuitable, having Stabilization methods and materials used in the a high percentage of expansive clays, but it was past were to be examined and evaluated. Fragile discovered that they worked well for both bricks and plaster wall decoration, rapidly deteriorating from plaster. Traditional historic materials and techniques moisture was to be stabilized and preserved. A futher were employed for repairs, supplemented in some cases purpose was to make the project serve as a testing by modern tools and equipment. Ongoing maintainance site with field conditions for the determination of ap- costs were evaluated. Wall voids were repaired with propriate, practical procedures for restoration of adobe adobe bricks or mud plaster, depending on the depth structures. of the damage. Satisfactory mix proportions were determined by trial and error, duplicating the original Implementation surface coating, and were applied to test walls. The stark white color this produced, which was a visual The primary problem to be addressed was mois- intrusion on the monument, was tempered by the ad- ture infiltration into the massive walls, from an un- dition of a clay soil wash, which enhanced the overall determined source. A superficial surface investigation appearance. did not offer any obvious clues for the source of the Lengthy testing and careful maintainance cost water. Major wall cuts, often a practical approach for projections indicated that the use of original materials many earth buildings, were not adviseable because of and labor intensive methods would not be more costly the historic nature of the resource. Crack monitors than modern materials. were installed to check and measure wall movement A repair crew was formed of NPS maintainance and settling. Moisture sensors were placed in the walls personnel, from the monument and regional staff, at regular intervals and at different heights and depths supplemented by local unskilled labor, including Uni- so that a profile of the moisture levels could be versity of Arizona students and faculty. Training ses- determined. Monitoring of these sensors for several sions were held and various team assignments were years indicated that the probable moisture source was made, matching natural aptitudes with the tasks to be from capillary action from the base of the wall. performed. Work commenced and was completed in a These profiles apparently had some seasonal timely manner. On completion of repairs, the monument variation. Cement stuccoed walls, preventing the evapo- presented a pleasing appearance, integrating old and ration of wall moisture, and the insertion of stabilized new surfaces neatly, obviously of the same basic ma- adobe bricks had caused moisture transference to other terials, but delineating old from new in a subtle manner.

124 The visitor center was built in the 30's by One outstanding exhibit is a small diorama of the the Works Progress Administration during the great interior of the church during its peak period. The monu- depression. It was designed in the architectural style ment is intact for visitor enjoyment in the actual spaces of the original mission buildings, and built of adobe used, and the diorama offers the fully restored space bricks, using many hand labor techniques. It contains appearance at a minimum cost, as opposed to full total artifacts, models and exhibits of significant features. restoration of the monument itself.

125

Adapting Adobe Buildings and Monuments to New Use

Roberto Samanez Argumedo

Preliminary Remarks function for which it was destined. This explains the fact that some buildings which remain standing today As opposed to other artistic expressions, such as have been admired by contemporaries and forgotten music or literature, which can be copied or conserved later. by oral tradition, architectural creations are linked to Thus we see it is not the monument that changes, the materials which form them. When these materials but the mentality of the people, who change their way disappear or suffer decay, the architectural work dies of feeling about historical monuments and their way as well. In this inevitable natural cycle, the need arises of valuing them. to preserve the works that remain, while human histcry Our century is characterized by the importance goes by. given to history; consciously or unconsciously, we all Materials, however, are only one of the compo- perceive it — even if we are mere observers of changes nents of the architectural works inherited from past and events. Carlo Ceschi, the late master in restoration, generations. The historical character, the testimonial used to say that, to see how immersed we are in history, condition and aesthetic expression of these works are it suffices to observe how even moderately-educated factors linked to them; this is why it is so important people can identify the historical period of the monu- —and at the same time difficult— to preserve this ments of their city. heritage from the past in an authentic manner. In this context, it is easy to see how theories Architecture, on the other hand, is always linked have been established, as well as ethical principles, to the aesthetics of a given period, as well as to the seeking an authentic conservation of the past and how

127 a technology of restoration (related mostly to the older Firstly, because a new use, quite different from the and more abundant experiences, that is, the European original one, can have more respect for the integrity ones) has emerged. In these brick or stone edifices, of the building than to continue using the building in experience accumulated during half a century of sound its original function. He gave as an example the restoration work has been applied. We should, however, conversion of a Renaissance palace into a modern home. point out that when dealing with earth as a building This can only be done with changes which affect it more material, we confront different experiences and tech- or less seriously, and which are inevitable requirements nologies. of modern life; adapting it to a Museum or cultural Without discarding universally valid theoretical center, on the other hand, can be done with less principles, the context where adobe historic buildings sacrifice. are located (usually underdeveloped countries) makes it impossible to apply the aforementioned technology. He also considered that the distinction between "living" monuments and "dead" monuments should be As an alternative, a technological adaptation is debated, for these concepts are based on an empirical proposed, applying the technology which is more approach to the problem. If one wanted to refer to a appropriate to the financial possibilities of under- monument as "living", because it could be used, one developed countries and which implies a return to the should remember that many ruins are more alive and traditional building methods and artisanal techniques "usable" than many complete monuments. He proposed used in the past. the statement to read thus: "That the monuments that Experiments in adobe restoration are quite conserve their internal spaces intact be destined to recent, compared to those of stone, masonry or wood. functions which will not go against the formal configu- As we have stated, in all monuments one must conserve ration of those spaces". not only the form but the material of the building itself, which embodies its personality and aesthetic expression. This last definition is very precise and contains In the case of adobe, this is truly a challenge: one the ideas that can be a starting point and orient us must restore these buildings, not make them into copies when we consider adapting an old adobe edifice to or variations of the monument existing before inter- contemporary use. vention. The precautions and recommendations are not to be taken dogmatically or rigidly, because the scope of pcssible adaptations of a building to new use is immense and each case is a specific problem. Oftentimes, it is Criteria for Adaptation hard to obtain funds for the conservation of historical monuments and the possibility of giving them a practical Twenty years ago, during the International use —in many cases— justifies an investment which Restoration Conference held in Venice which gave rise would not be considered otherwise. If the fact that to the Venice Charter, Piero Gazzola brought some an old building can be adapted to contemporary use important corrections to the final recommendations. It with all the necessary modern confort were understood, had been proposed that: "when adapting edifices we could avoid the idea (held by many public officials considered as 'living monuments' to new use, they and experts) that substituting new for old is always should be destined to functions or uses not too best. different from their original end, so as not to alter When dealing with the conservation of historic —when adapting them— the essential parts of the centres, it has been confirmed that it is not only building". necessary to have legislation for the protection of these Gazzola considered that, although the intention areas; it is also necessary to establish to avoid adapting a building to a practical use in order plans, studying the typology of the buildings so as to to avoid negative results on the integrity of the building propose a new function for them and introduce modern was valid, this intention had been stated erroneously. comforts without altering the traditional structures or

128 moving the inhabitants from one neighbourhood to their adaptation to contemporary use, emphasizing the another. importance of this not only because of the intrinsic Every day, more and more adobe, tapia and value of the buildings, but because their adaptation to quincha buildings are lost in the historic centres of new use can teach contemporary architects. It is true Latin America. Thus, it is urgent to establish pilot that adapting buildings of the beginning of the indus- projects showing that one can, at the same time, pre- trial age is easier than converting an important historic serve the historic past and solve the acute housing monument which, by its very nature, requires the inter- problem, present in all these countries. vention of a specialist, and limits the choice of possible Unfortunately, there is no awareness of the new uses. fact that what is happening to our monuments and When intervening in these buildings, one must historic complexes is similar to what happened in other strive to maintain and respect them. This contemporary parts of the world, where economic pressures and real- position is not new: the adaptation of buildings to new estate speculation changed the use of buildings: these use has been done in the past. During the Renaissance, became shops and later, collective dwellings which were Michaelangelo adapted a great Roman edifice, the Baths literally hovels. When the process of social change of Diocletian, and converted it into the Church of Santa was accelerated because productive activities became Maria degli Angeli. We have some examples of this in concentrated in few hands, the buildings in the central our midst: the first convent of Santa Clara, built in zones were demolished and substituted by new ones. Cusco in 1558 was transformed in 1649 into the House This produced congestion and deteriorated the quality of Don Jeronimo Luis de Cabrera y La Cerda, Mayor of urban life in these areas, once more there was a and Chief Justice of the city. This was done using the migration towards the peripheral areas. Modern cen- walls of the church as the façade. tres sprung up, centred around business activities. This In Germany and England many churches which process takes place, with some variants, in most cities: are not used for religious services have been trans- improvisation, tolerance, the acceptance of initiatives formed, with the approval of the ecclesiastical that are merely commercial ventures, have had a sad hierarchy. The Anglican church studied the functions result for the cultural and archaeological heritage. If it considered appropriate for buildings not used for we want to learn this lesson and avoid its repetion, religious services any more; it proposed they should we must urgently renovate old buildings for use as be used as concert-halls, libraries, social centres, exhibit homes, as well as other public buildings which have halls and museums. become obsolete, assigning new functions to them, but In Urbino, Italy, the well-known architect, Gian- always in keeping with the needs of the community. carlo de Carlo adapted an Agustinian convent of the XVth century which had been used as army barracks Adapting Historic Buildings to a university facility having a library, auditorium and classrooms. The possibilities of the building were It is interesting to analyze a precedent; that is, exploited to the hilt; the appearance and character of the contemporary use of industrial buildings of the the edifice were preserved. The library, reading room XV I I I th and XIXth centuries. Most of these inter- and book deposit which needed large spaces were built ventions were carried out in England, Germany, Italy underground, under a garden and the cicister. This and other countries in Europe; this was also done in solution, which required complex work, is an example the United States. In all cases, it has been very of adaptation to new use, while maintaining the char- important to determine the social or cultural signifi- acter and original style of the convent. cance of the activity to which the building was to be We do not want to continue using European adapted. examples. To conclude, we will cite the case of England, The well-known US publication, Architectural where rural buildings such as barns, have been adapted Review devoted one of its issues to old buildings and to music, dance and theatre centres. Thanks to the

129 support of private British Foundations, such as the in Lima at the start of the XVIIIth century. This stately National Trust, these modest rural edificies have been home, with its Sevillian tiles, tall galleries supported saved and stand as testimonies of another age in an by superimposed corbels, and Mudejar arches, has industrialized society. been restored and serves today as the seat of the Ministry of Foreign Affairs. Another interesting exam- Adaptation of Adobe Buildings ple, the Casa de Oquendo, of the end of the XVIIIth to New Use century, with its five balconies and a portal as high as the house itself is presently being restored to be In Brazil, the National Institute for the Safe- used by various cultural associations linked to the guard of the Artistic and Historic Heritage, with Institute de CooperaciOn Iberoamericana. the support of the Programme for Historic Cities of the In the city of Ayacucho, on the occasion of the Planning Secretariat has established an interesting 150th anniversary of the Battle of Ayacucho which put programme for the preservation of the artistic and an end to Spanish colonial dominion in America, an historic heritage. Many of the monuments included are interesting initiative was taken by the public and built in rammed earth and the interventions performed private banks: each one of the commercial banks on them constitute interesting examples of restoration acquired an ancient house. These adobe and stone of this material. houses were restored, and used as headquarters for The house of Antonio Diaz in Ouro Preto, the these banks, as well as for the College of Architects. Intendencia in Sabara, which was transformed into the Finally, in Cusco, a great number of Colonial Gold Museum, and many others have been salvaged and adobe buildings have been adapted to contemporary converted into Museums. These buildings have become use. The first intervention was the restoration of the special tourist attractions in the circuits established in home of the writer Inca Garcilaso de la Vega, son of a the historic cities. Spaniard and an Indian. The house initially was In Chile, interesting restoration work has been transformed into an Art Museum; today it houses the carried out in the "haciendas" of the central valley; Historical Archives of Cusco. these constitute important examples of adobe archi- In the framework of the Technical Assistance tecture and include the plantation houses, warehouses Programme of UNESCO and the COPESCO Plan, and annexes. The Hacienda at Calera de Tango, which between 1975 and 1979 the following monuments, among was owned by the Jesuits is a vast complex of horizontal others, were restored: the Jesuit College of San Bernar- buildings having a facade more than 200 metres long, do, built in 1620 and probably one of the Cusco as well as 10 patios. Although it had suffered modifi- buildings which has been used successively for more cations, today it has been restored thanks to the functions —many of them inadequate. It was a school, initiative of a philantropist. Other cases include the the seat of the Departmental Junta in 1828; it housed house at Lo Fontecilla, near Santiago, restored by a the Post Office, it then became seat of the Court of historian, and the Hacienda Lo Contador, an XVIIIth Justice, and, at the turn of the century, was transformed century building which houses the School of Archi- into the seat of the Provincial Council, until the 1950 tecture of the Pontifical Catholic University of Chile. earthquake. Twenty-eight years after the quake it was We could continue with other Latin American restored and the old College became the headquarters examples of adaptation of adobe buildings to new use, of the National Institute of Culture. yet we believe it would be illustrative to comment on Another monument restored within this same the buildings which the participants in the Symposium programme was the Casa del Almirante, the best exam- has a chance to visit, that is, the Peruvian examples. ple of civil architecture in the city, outstanding because One of the richest and most attractive homes in of its mullioned windows and a façade crowned with the Colonial architecture of Latin America was, without two coats of arms, as well as for its coffered ceilings a doubt, the Palace of the Marquis of Torre Tagle, built and a patio with arches on two levels. After resto-

130 very unsatisfactory manner. There are still numerous ration, part of the house was transformed into the buildings of historic value in Cusco which have not Regional Historical Museum, while another part houses been restored and have been adapted inadequately. a section of the University of Cusco. The Banco Hipotecario sponsored the restoration Such is the case of the three buildings which house the Guardia Civil (Police Force) ; the seats of different of the House of Fernando de Vera y Ztiniga (XV11Ith political parties; or the many ones which, adapted in a century) which, during the last century was the home makeshift way, are used as stores. of the writer Clorinda Matto. This building has valuable murals and today is the headquarters of the Bank. The In the last years, inadequate adaptation of some Community House of Las Nazarenas, also an old adobe buildings has meant irreparable loss of the cultural building, has been adapted to serve as administrative heritage. The House of the Marquis de Valleumbroso headquarters for the COPESCO Plan, while the House was occupied by a political organism, until a throng of of the Marquis of Valleumbroso is being restored to university students set fire to it. Recently, another fire house the Regional School of Fine Arts. demolished a business concern, located in a large A larger adobe building, the Seminary of San portion of a XVIlth century building. Antonio Abad, is being restored to serve as hotel; this is probably the first example in the city where a The examples analyzed and the comments building destined to this end is transformed with respect expounded have allowed us to gather information on for the original edifice. the adaptation of adobe and rammed-earth buildings. We should emphasize that many adobe buildings Valid conclusions may be reached and applied to the in the city were repaired and adapted to become different contexts where adaptation of old buildings to hostals or small hotels. However, this was done in a new use is sought.

131

Protection and Conservation of Adobe Historic Complexes

Jacques Verite

society and to the growing complexity of its organi- 1. Historic Complexes and zation" (1). Building Materials — for the building technology: on the various existing In order to identify the place of earth as a possibilities. There are houses covered with earth or building material in historic complexes, the different excavated in it. Trogloditic houses; "quincha" (wattle architectures, technologies and the material itself must and daub); layers of plastic mud (barroca in Brazil); (tijuco in Brazil); be considered. champas (Argentina); mud shells These differences depend: layers of mud placed on rush-matting; hand-made adobes, on environmental factors, moulded adobes, rammed blocks and compressed earth —for the architectural styles: (tapia, adobon) are also used. such as climate, topography, nature of the terrain, ma- — for the material itself: on the nature of the soil used terials available; on the degree of technical develop- and its transformations (added materials and clay ment reached by a society; on social and cultural stabilizers). factors — but, above all "without falling into a linear evolutionism... one must consider the habitat in relation This general level, however, is not sufficient to to the development of the productive forces of a given explain the variety existing whenever earth is used in

133 historic complexes. Following the methods applied by — Finally, even in societies where writing is unknown, linguists in the study of the vernacular tongues and the cultural exchanges produce a unity in diversity: the dialects, we will try to determine specific rules. It is Tiahuanaco or Inca horizons have a unitarian influence, essential, in order to do this, to emphasize the rupture identifiable in the regional variants with which they between the vernacular and the modern (2). coexist or on which they are superimposed.

Vernacular Architectures The Strata: "Culture" Architecture Vernacular architectures are defined as "habitats and Vernacular Architecture conceived and produced in and for specific place "Culture" architecture is defined as the archi- and culture" (3). At a given moment, these have a unity tecture transmitted and taught by written documents. within a geographic space: they constitute an area. a. The role of "culture" architecture a. Areas "Culture" architecture is applied to monuments The regional variations, differences and specific in the first place; it intervenes in the modification of forms define the architectural areas. In Peru, we can the architecture, the technology and the nature of the define architectural areas following two : along building materials. The research undertaken by ar- the coast, variations can be observed from valley to chitects against earthquakes in Latin America is an valley; within one valley, perpendicular to the coast, example of this: "Soon after the earthquakes of 1606 variations are also visible. and 1609, a council of architects decided to change the roof of the Lima cathedral, which was originally a Limits and Transition Zones b. with arris domes substituting it by ojival- Actually, these areas are crossed over by dif- style vaults. In 1639, Vasconcellos adopted... a system ferent architectures, technologies and building ma- of vaults... made of quincha or bahareque. Quincha is terials, so that their limits become relative. This leads an ingenious system, using wood and straw with mud, us to define transition zones. which was employed to build the arches. It is a very lightweight ensemble and acts very flexibly in the —the different areas may be crossed over by simi- vibrations produced by earthquakes" (6). larities linked to the geography and the possibility of contacts. But the similarity depends on the criteria b. The knowledge of "culture" architecture used when identifying the different forms of Pre-Hispanic adobes found in Peru, we find a common element in "Culture" architecture can be transmitted and the technology employed: they are all hand-made (4). superimposed on vernacular techniques. Thus, for quincha: "this innovative system became popular in the — In an area, similar architectures are built with differ- 17th century in the Peruvian coast and the south of Ecua- ent materials and differing technologies: throughout dor. We can state that few houses or buildings of the 6000 years of history, the unity of the Chilca valley Colonial period or the 19th century remain today in the cannot be identified either by the manner of building coastal region which did not use this system" (6). or by the changes in materials (5). But the propagation of "culture" architectures —The evolutions or regressions, due to the intervention of specialists or to a type of building of a particular is also subject to variations: status, lead to unclassifiable variations. In the Southeast —if the process is slow, the technical advances or local of France, for example, in a zone 5 km. around the town practices create particular types. of Viozan, there is a style of building where adobe and —the different social groups integrate innovations small stones are used in a chessboard pattern; it is differently. Vernacular architecture can coexist with unique in its kind. "culture" architecture.

134 These phenomena were described by Tschudi cement are also a result of technical progress. Contrary when he visited Lima in 1839 and 1842: "the manner to the older binders, these have a positive capacity to of building the houses... may be considered typical, resist traction. although there are variations. The walls of the large —Technologies and architectures: changed slowly until buildings are either adobe or brick; those of the small the end of the Second World War, when concrete and houses are merely cane, covered with mud and then cement blocks began to be widely used. During this painted (7). transitional phase, earth as a building material dis- appeared but some of its technology survived: in c. The feed-back effects France, we find compressed blocks made of slag and Feed-back effects take place between vernacular lime, as well as concrete made of lime and cement, architecture and "culture" architecture. The example using the system of moulded earth. of Latin America is characteristic, for here "the ideas, forms, models and even artists transplanted had to b. Today: earth in the historic complexes adapt themselves to the conditions of the "new world" The contemporary position of earth as a building (6). It is for this reason, for instance, that —during material is defined by two extreme situations: Colonial times— there were differences in the size of — buildings made of earth have been destroyed. the adobes: "In the highlands, blocks 41 to 61 cm. long — the practice (techniques) of building with earth still and 19 to 30 cm. high are used; on the coast smaller survive. In this case, this produces a new vernacular dimensions are used" (4). stratification whose variations are the following: - the composition of the material is modified, because Conclusion: Architectures of the Past the old stabilizers and additives are not used. (The material is thus deficient, if compared to the older one). The architectural complexes of the part are Sometimes, the old additives and stabilizers are sub- characterized in this analysis by: stituted by modern binders (laterite/lime or soil/ —Areas with imprecise limits, crossed over by elements cement). of unity and variations. - the techniques are modified because of economic —A stratification of architectures, techniques and ma- reasons (the required time for mixing or drying is not terials, some of wich still survive today. observed). - the architecture and the organization space are modified: an effect of feed-back has taken place with Modernism and Remnants the prevalent architectural and urban styles. They a. The change in the XIXth century reflect a new social organization. — Between these two extremes, the position of earth as We will not discuss the changes brought about a building material is very variable. There are historic by the industrial revolution, but will only examine complexes where earth continues to be predominant. three aspects: But, often, these are only remnants (let us bear in mind —The transportation of materials: this brought about that these are stratifications). a modification in the act of building, caused by technical This earthen heritage is in danger of being destroyed. progress. A characteristic example is the action taken but we must equally stress that any interventions in by Haussmann in Paris: he was the first to have the constructed space in the historic complexes has both available the technical means to destroy the wood and negative and positive consequences: mud city which was Paris at the beginning of the XIXth - the actions leading to modification and repair of the century. habitats contribute to the destruction of the remnants, —Contemporary binders: artificial hydraulic lime and but the new constructions, built over old earthen houses,

135 or the use of new plasters are ways of conserving earth. is difficult, due to the characteristics of the soil - the actions taken by the specialists in restoration components and to the nature of the binder, clay: earth who work in the monuments included in the historic is a material with a weak resistance to traction. complexes participate of certain new fashion or styles, —building with earth is expensive. whose effects can be either positive or negative for —its thermophysical characteristics are nothing special. the conservation of the stratitifations of the material earth. (For example: the restorations of the Alhambra b. Actions on stratifications and remnants in Granada). Stratifications and residues are sometimes hard to identify, and are often justifiably destroyed during Conclusion restoration operations undertaken in "buildings" with no historic or architectural value" (UNESCO recommen- Within an architectural area, earth is identifiable dation). across the variations in the material, the techniques used, the architecture and the organization of space. c. Scientific conservation It is only within a stratification that there is The conservation of historic complexes is not a unity and we have found the following: scientific act; this is stated in the same UNESCO recom- mendation which says: "Restoration works should be — pre-industrial types: founded on scientific bases... More attention should - dominant vernacular be given to the harmony and aesthetic emotion which - "culture" models (sometimes superimposed) arise from... the different elements present in the - "culture" vernacular (which integrates into the ver- complexes..." (the use of the conditional is a confes- nacular elements of the "culture" models) sion: harmony and aesthetic emotion are social values, - "culture" model/vernacular (which integrates into essentially variable). the "culture" models elements of the vernacular) - dominant popular (with some traces of the "culture" models) Ideological Difficulties - popular/vernacular (found in the edges of the urban a. The importance of modernism sites) —modern types: The products and the incidences of a dominant modernism (real-estate speculation, hygiene, materials - one or several vernacular modern types, identifiable market, loss of technical know-how) are all partly the depending on the social groups and the proportion of cause of the disappearance of the earthen heritage, modern materials used. be it directly (by destruction) or indirectly (by disdain).

b. The dangers of nostalgia 2. The Problems of Conservation The opposite attitude is also very dangerous. By We must act not only on a material, but on the idealizing the past, generally limited to one of its superimposed or mixed imprints of different cultures. cultural stratifications, nostalgia can destroy as much as modernism (for example, the reconstruction of Cusco after the 1950 earthquake). The remnants (remains) Technical Difficulties become folklore, because appearance is preferred to substance. a. The basic problem: the characteristics of earth as a building material c. The attitude of the restorer —The transformation of soil into a building material The restorer, whether he wishes it or not, is

136 influenced by these ideologies for his action is not Earth in the Urban World scientific. A. Stevens, for example, uses erroneous judgement when writing on the condition of the roofs a. Monuments of the Palaces at Abomey (Benin): The solution for protection and conservation, and, in particular the use of appropriate tenhnologies 1. "The old roof, made of aluminum sheets.. have been considered in this Symposium. Integration: colour, when oxidized, is similar to that of the ground; ... a foreign material. b. Speculation in the urban context 2. The new roof made of aluminum sheets. Integration: none" (8). Because nostalgia revalues ancient things, people with the necessary financial means try appropriate Are metal sheets in Africa —and elsewhere — parts of the historical complexes. foreign or vernacular? Must a roof be "integrated?". Protection should be carried out: —by legal action. —by example. This example should come from the specialists and should be transmitted, above all, to the 3. Possible Solutions for the Protection actors (architects, enterprises, administration). We will and Conservation of Earth cite as an example action taken by architect C. Sanchez Gomez in Granada and we will emphasize the role that Earth in Rural Architectures private enterprises or associations can play. In the "Seminar on the Conservation of the c. The degraded urban context African Heritage" held in 1982, the working group on Two examples, two solutions: conservation of the rural architectures arrived at these — In Tunis, small teams of workers financed by the conclusions: Town Council and directed by architects-restorers are ... what must not be done: responsible for maintaining the visible parts of the habitats. Owners and tenants are also urged to revalue —transportation of whole houses to the city... their homes. —conservation aimed at tourism, without regard for the —In the Abaicin in Granada, urban planners and mu- opinion and real interests of the population... nicipal architects, together with representatives of It would be more reasonable to foresee different neighbourhood organization have acted together. A practices in regard conservation — and especially: strong and responsible community can act effectively in —to preserve in situ whenever possible, which implies protecting and conserving its heritage — even if the a policy of adapting these complexes or centres to a risk of creating a new stratification (vernacular/mod- new use. ern/restored) exists. —to substitute using documents ... this will allow conservation ... at least in memory. 4. Conclusion —in some exceptional cases, especially for structures which are obsolete, one might consider a more classical Earth disappers more rapidly in the historic in situ conservation of some specimens, eventually complexes than the rest of the cultural heritage, which changing their function" (9). we all know slowly disappears day by day. We will be aware of the importance of its conservation if we try The limits in these propositions show that earth to imagine its future — which will possibly be very in the rural architecture stands between disappearance similar to that of the French vernacular habitat (a or the museum. large part of which is built with earth) : "Probably, in

137 the year 2000, the number of persons who will enter 5. ENGEL F., Geografia humana prehistérica y agricultura pre- colombina de la quebrada de Chika, Lima, Universidad Agraria, into ancient residences will be one percent (of the 1966. French population) . It is not only a technical or fi- 6. PATRIMONIO CULTURAL DE LA HUMANIDAD, N° 10, nancial problem, nor is it related to building permits: Paris, UNESCO, 1977. it is a problem of society". (10). 7. TSCHUDI J.J. von, Testimonio del Perti, 1838-1842, Lima, Pert, 1966. 8. STEVENS A., "Les palais royaux d'Abomey. République Populaire du Bénin. Sauvegarde et mise en valeur", Ankara, References ICOM, ICOMOS, 1980. 1. CENTLIVRES P., "Habitat", in Encyclopaedia Universalis, 9. SEMINAIRE DE PERFECTIONNEMENT SUR LES PRIN- Supplement, vol. 1, p. 697 et s., 1980. CIPES ET LES TECHNIQUES DE CONSERVATION APPLI- 2. GUIRAUD P., Patois et dialectes français, Paris, Puf, 1968. CABLES AU PATRIMOINE ARCHITECTURAL AFRICAIN, 3. ALEXANDROFF G. et J.M., Architectures et climat, Paris, Abidjan, ICA, ICCROM, UNESCO, ATELIER: "Les architectures Berger Levrault, 1982. traditionnelles ont-elles un avenir?" Politique de conservation, 4. SAMANEZ ARGUMEDO R., "Los monumentos de adobe en 1982. el Pert y los casos de restauraciôn efectuados en la zona de 10. Les résidences secondaires en France, Paris, Notes et Docu- Cusco", Ankara, ICCROM, ICOMOS, 1980. ments, 1972.

138 Conclusions and Recommendations

Conclusions —There are towns and cities which, due to their geogra- phic location, economic and technological development —This Symposium dealt with the topic of adobe conserva- and availability of labor and regional materials, have tion; monetheless, it also considered, in a global no other alternative but to use unbaked earth in the manner, all architecture made of earth, be it archaeolo- construction of their buildings and dwellings. gical, historical or contemporary, partially or totally The use of this material identifies and character- built with this material. izes the urban landscape man and his city — creating — Inasmuch as adobe is a material that has been conti- a harmony with the surrounding environment, be it nuously used throughout time, different cultures have natural or built by the hand of man. been able to perfect their techniques, giving rise to It is necessary, therefore, before any inter- specific building methods which constitute a living vention, to know the cultural characteristics of the testimony of the history of different nations. different peoples, in order to avoid confrontation with Architecture made of earth, supported by the use the preexisting culture. of local materials, lead to the definition of direct and unmistakable forms based fundamentally on functional Historical monuments and, in a general way, demands and lifestyles implicating, oftentimes, tra- adobe buildings have suffered severe damage due to ditional, social and religious aspects of shared life and the rigors of weather, natural disasters and man himself. beliefs. The disadvantages associated with this behaviour are 139 being overcome, thanks to the research developed in nature of materials, techniques employed and the recent years. historical period of construction. The original architec- tonic intention must be maintained and respected with simplicity and sensibility. Recommendations —Because historic centres built in adobe are the —Upon analysis of the use and techniques of unbaked product of a society, they should be valued and earth in construction in the Latin American area, protected as the patrimonial legacy of the human group specifically, it was the general consensus of the partici- which created them. They are the cultural heritage of pants in this Symposium that the concepts which the inhabitants and should be considered as living transpired are applicable generally throughout the urban organisms, whose significance remains in force in world and especially in developing nations. ccntemporary life. — It was not the task of this Symposium to call into —Knowledge of the values of the cultural tradition will question the Venice Charter or any other document guarantee the harmonious development of the cities and drawn up by governmental or non-governmental con- their inhabitants. ventions whose principles have been internationally In keeping with the rapid development of pres- accepted, but to enrich them with a particular chapter ent times, urban dynamics and local technologies must devoted to earthen architecture. be taken into account when planning and designing the Hence, it is necessary to perform complementary development of historic cities built of mudbrick. studies on the topic of adobe and its conservation — The problem of slums in historic centres should be under the sponsorship of UNESCO, ICCROM, ICOMOS viewed not only as a problem of design, but as a social and other specialized bodies. problem as well. The solution of economic and main- —These studies/documents should compile data, among tenance problems is critical in order to erradicate it. others, on the uses, techniques and typology of existing Hence, in the case of protection of cities, experiments edifices and cities built in mudbrick, according to the are proposed, which will encourage self-help in con- historical, social, cultural and economic reality of each struction, with international technical assistance. Spe- area. cial attention should be given to maintenance; this With a view to establishing these studies, the should be done using preferably the same techniques organization of regional and sub-regional networks of employed in the original construction and homegeneous specialists should be considered. These experts should materials. set up an interdisciplinary, geographically well- represented team. It was suggested that ICCROM, —With regard to archaeological sites built with earth, UNESCO and UNDP, through pertinent channels, make it is recommended that a detailed inventory be the necessary arrangements in order to carry out this established in collaboration with agencies such as work. UNESCO, so that governments and specialists may pro- The output of these studies should be compiled gram their research, restoration and maintenance acti- within two years at ICCROM and would become part of vities. the existing data bank. — In relation to the preservation, conservation and These studies shall prove extremely useful, es- restoration of the historical sites, it is recommended pecially in training courses given at ICCROM or at that a group of experts establish the criteria to be other national, regional or international institutions adopted, taking into account the interests and the which deal with the conservation of adobe and other knowledge of the community itself, since the community materials made of mud and unbaked earth. is heir to the original tradition. — In the case of intervention in architectural works This should be reflected, as well, in accompanying made of earth, the architectonical language must be architecture, which must take into account the popular taken into account, including the original structure, the know-how of the region.

140 Likewise, the use of traditional techniques, mends a massive dissemination of the qualities that can be attained, so that mud architecture continues to where they are still known, is recommended for com- be used not only by lower-income groups but by all pletion or repair of ancient edifices, thus ensuring the sectors of society. survival of expertise in the use of analogous techniques and materials. —Adobe structures used in monuments and historic Governments should give special emphasis and sites should be studied with the purpose of safeguarding interest to the preservation of historical evidences made them against earthquakes and other natural disasters, of mud in order to ensure their survival as the cultural taking advantage of the latest technology and research heritage of future generations. This should be done developed in this area. with support from regional and local legislation which —Studies on the construction and restoration of present- will guarantee its application. Special tax exemptions ly-damaged monuments located in seismic regions should and economic incentives should be given to those who include a complete seismic analysis of the edifices, maintain these buildings. leading to the interpretation of causes of faults and — Historic centres should reflect and genuinely express potential damage. This, in turn, should encourage re- the life of the society which inhabits them, and not be pair projects which will avoid such damage in the future. merely "scenery for tourists". Competent agencies should channel all pre- — ft is recommended that international credit organi- ventive actions in order to ensure that specialists will zations, as well as national, state and private ones, allot be in charge of rescue and restoration operations in special funds for the restoration, conservation and the case of disasters. preservation of cities, buildings and dwellings made of Due note was taken of the work being carried mudbrick. out in areas affected by natural disasters, such as — One must bear in mind that adobe buildings, owing to Popayan, Colombia (earthquake) and the north of Peru their specific construction quality, are not adaptable to (floods). any new use. Hence, careful study should be given to The Symposium recommended taking into account any foreseen changes, taking into consideration suit- the conclusions and recommendations of the Seminar on able structural and functional adaptation. the Protection of Historic Monuments in Seismic Areas — Knowing that the installations will become obsolete organized by UNESCO/UNDP, UNDRO, ICOMOS and long befcre the structure itself, the Symposium recom- the OAS in La Antigua, Guatemala and published by the mends that in projects designed to give a new use to UNDP/UNESCO Regional Project on Cultural Heritage, mudbrick buildings, the mechanical fittings and installa- as well as the establishement and publication of studies tions be incorporated in a totally reversible manner. on the protection of adobe monuments, historic centres — It is specially recommended to study the adaptation and buildings located in seismic areas. of mudbrick buildings for housing, thus ensuring their — When intervening in the structural reinforcement of survival and, consequently, that of the historic centre. monuments all possibilities of using the same materials —Taking into account the acute housing shortage felt and/or traditional techniques should be exhausted throughout the world, it is recommended to promote before employing other materials, foreign to adobe. earth architecture, given its proven economic and —Bearing in mind the specific problems of painted surfa- climatic advantages, incorporating technical advances ces on adobe wall's and the need to improve preser- only when necessary. To this effect, it is recommended vation techniques, it is recommended that a pilot to carry out studies on the functional characteristics project be established for study, experiment and of adobe housing, taking into account technical, eco- training of personnel specialized in the conservation nomic and social aspects. of these paintings in a country possessing a rich her- —Bearing in mind the need to eliminate prejudice itage of said paintings and especially trained personnel. linked to the use of this material, the Symposium recom- For the purpose of continuing work initiated in this

141 field in Peru, it is recommended that this project of buildings using traditional know-how. studies and training be established in Peru with the —These studies should be published and made available suppert of UNESCO and ICCROM. to professionals in order that they be applied both in —An international study-group shall assess, within two conservation and in the construction of new edifices. or three years, the results of this program and arrive For this reason, the Symposium recommends to continue at relevant conclusions. holding periodical specialized meetings. —Universities and higher-learning centres should place It is recommended that the working papers particular emphasis on training and both experimental presented at the Symposium, enhanced by the lecturers and in situ research, seeking to improve the qualities and discussions, be included in a special publication to of the material. Special efforts should first be made be distributed worldwide by the organizers of this to reinstate traditional techniques, and then to study meeting, i.e. UNDP, UNESCO and ICCROM. It is also the possibility of incorporating recent technical de- recommended that UNESCO publish didactic material velopments, in keeping with economic, social and cultur- (in the form of booklets, exhibits and audiovisual aids) al characteristics. on the history and conservation of adobe. For this — It is recommended that intensive courses on adobe purpose, private and public, national and international conservation be given at existing training centres (such financial support should be sought. as universities) and that this topic be included in —The conclusions and recommendations herein stated national, regional and international courses on restora- engage the participants in this Symposium to follow tion and conservation of monuments and historic sites. them henceforward, and to enrich and divulge them in —Training relative to the technology of the material their respective countries, so that earth architecture should also include middle-level professionals and, may occupy the place it deserves in the context of the primarily, the social groups who build their own Cultural Heritage of Mankind.

142 Roma — Milán Conferencistas / Lecturers ICCROM — IILA —ALVA BALDERRAMA, Alejandro —LEWIN, Seymour (USA) ICCROM — Roma New York University —CHIARI, Giacomo (Italy) New York — USA ICCROM — Roma ICCROM —CROSBY, Anthony (USA) —MORALES GAMARRA, Ricardo (Perú) National Park Service Instituto Nacional de Cultura Colorado — USA Trujillo — Perú ICCROM UNESCO / PNUD — ERDER, Cevat Director — REYES ZEPEDA, Gilberto (México) ICCROM — Roma Gobierno del Estado —ESTABRIDIS CARDENAS, Ricardo (Perú) de Tlaxcala — México Instituto Nacional de Cultura UNESCO / PNUD Lima — Perú —ROJO ANABALON, Sergio (Chile) UNESCO / PNUD Consultor en estructuras, Santiago de Chile —HELG, Franca (Italy) UNESCO / PNUD 143 —RUTENBECK, Todd (USA) — LEME GALVÄO, José National Park Service Fundagäo Nacional Pro Mémória Colorado — USA Brasilia, Brasil ICCROM —SAMANEZ ARGUMEDO, Roberto Colombia Instituto Nacional de Cultura —MARTINEZ, Gloria Cusco — Perú Fundación para la Conservación y UNESCO / PNUD Restauración del Patrimonio Cultural —SCHWARTZBAUM, Paul Bogotá, Colombia ICCROM — Roma —CASTRILLON, Tomás —STEVENS, André (Bélgica) Servicio Nacional de Aprendizaje Consultor, Gobierno de Bélgica Popayán, Colombia ICCROM —VERITE, Jacques (Francia) Consultor UNESCO — Paris Cuba UNESCO/PNUD —CUADRAS, Zoila —VARGAS, Julio (Perú) Ministerio de Cultura Pontificia Universidad Católica La Habana, Cuba Lima — Perú UNESCO/PNUD Chile —CERVELLINO, Miguel Dirección de Bibliotecas, Archivos y Museos Copiapó, Chile — BINDA, Edwin Participantes / Participan ts Universidad Católica de Chile Santiago, Chile Argentina — YRARRAZAVAL, Amaya —MONK, Felipe Universidad Católica de Chile Centro de Estudios de la Santiago, Chile Sociedad Central de Arquitectos Buenos Aires, Argentina —VIÑUALES, Graciela M. —BOLAÑOS, Guillermo Universidad Nacional del Nordeste Museo del Banco Central Resistencia, Argentina Quito, Ecuador —MUÑOZ, Patricio Comisión del Centro Histórico de Cuenca —PRADO RIOS, Luis Cuenca, Ecuador Instituto Boliviano de Cultura —DEL PINO, Inés La Paz, Bolivia Centro de Investigaciones Ciudad Quito, Ecuador Brasil —ORTIZ, Lenin —ROMANELLI D'ASSUMMO, Livia Concejo Provincial de Pichincha Fundacäo Nacional Pro Mémória Programa Cochasquí Belo Horizonte, Brasil Quito, Ecuador

144 España Mali —BOUARE, Nianti —SANCHO RODA, José Centre National de Recherche, Ministerio de Cultura Experimentation, Bátiment et T.P. Madrid, España Bamako, Mali Etiopía Nicaragua —HALLE MARIAM, Jara Assistant Architec Restorer — IBARRA, Asdrúbal Adis Abeba, Etiopía Ministerio de Cultura Managua, Nicaragua Estados Unidos —Mc HENRY, Paul Panamá Architect, A.I.A. —CABALLERO, Jaime Adobe Architecture Consultant Instituto Nacional de Cultura Albuquerque, New Mexico, Estados Unidos Panamá, Panamá —TORAL, Demetrio Guatemala Instituto Nacional de Cultura —CEBALLOS, Mario Panamá, Panamá Concejo Nacional para la Protección de Antigua Antigua, Guatemala Perú —MORALES, Jorge Mario —ARAOZ, Hernán Centro de Investigaciones de Ingeniería Instituto Nacional de Cultura Guatemala, Guatemala Cusco, Perú —ASTETE CANAL, Luis Corporación de Fomento y Reconstrucción Haití Ayacucho, Perú —10LIBOIS, Henri Robert —BECERRA CAMPANA, José Instituto de Protección Instituto de Investigación del Patrimonio Cultural Universidad Nacional San Antonio Abad Port-au-Prince, Haití Cusco, Perú —CARRILLO, Pablo Américo COPESCO —SOTO GEHLHAAR, Rolando Cusco, Perú Instituto Hondureño de —CORNEJO GARCIA, Miguel Angel Antropología e Historia Universidad Nacional de Trujillo Tegucigalpa, Honduras Trujillo, Perú —COSMOPOLIS BULLON, Jorge Banco Central Hipotecario Jamaica Lima, Perú —BARNES, Stanley —CHANG LAM, Luis National Gallery of Jamaica Concejo Provincial de Trujillo Kingston, Jamaica Trujillo, Perú

145 —ERMAN GUZMAN, Pablo Turquía Instituto Nacional de Cultura —IZMIRLIGIL, Ulkü Lima, Perú Ministry of Culture and Tourism — ESCOBAR, Freddy Istanbul, Turkey COPESCO Cusco, Perú —ESTELA, Bertha M. Instituto Nacional de Cultura —HOJMAN, Carlos Lima, Perú Intendencia Municipal de Montevideo —GALVEZ PEREZ, José M. Montevideo, Uruguay Arquitectos Restauradores Ingenieros Estudios y Servicios (ARIES) Venezuela Lima, Perú —DIAZ NOGUERA, Yazmin —GIBAJA, Arminda Complejo Cultural Helicoide Roca Tarpeya Instituto Nacional de Cultura Caracas, Venezuela Cusco, Perú —HOBAICA, Gustavo —MARROQUIN P., Jorge Fundación Grupo Tierra Cordiplan Instituto Nacional de Cultura Caracas, Venezuela Lima, Perú —PEÑA FLORES, Julio COPESCO Cusco, Perú Observadores / Observers —ROJAS, Julio —VARGAS MERA, Ramón Instituto Nacional de Cultura Oficina Regional de Cusco, Perú Educación de la UNESCO —TEJADA, Mario R. Chile Instituto Nacional de Cultura —VIAENE, Martín Lima, Perú Oficina Regional de Ciencia y Tecnología Portugal para la América Latina y El Caribe de la UNESCO —DE FREITAS TAVARES, Antonio das Neves Museu Monográfico de Conimbriga Uruguay Condeixa, Portugal —ROMANELLI D'ASSUMPÇÃO, Livia ICOMOS —MUÑOZ NAJAR, Antonio Senegal FORD Foundation —BERTHE, Mamadou Centre pour la Conservation des Monuments et Villes Historiques/Belgique Dakar, Senegal Oyentes / Auditors

Sri Lanka Bolivia —DE VOS, Ashley —ESCALIER, Rolando Design Group Five PARRANDO, Lourdes Colombo, Sri Lanka SANDOVAL, Freddy

146 — GALVEZ DE SNYDER, Lydia SAN T I L LA N, Amerlín E NACE TERAN, Olga — PIMENTEL, Víctor URQU IZO , Carlos Proyecto Nuevo Museo VELASCO, Luis Nacional de Antropología VILLEGAS, I anet y Arqueología del Perú Universidad Mayor de San Andrés —HOY LE, Ana María La Paz, Bolivia I I MEN EZ BORJA, Arturo DEL MAR, Carlos Chile MORON, Eddie — MANCILLA, René PAREDES, Ponciano Universidad del Norte SAAVEDRA, Luis Antofagasta, Chile SUAREZ, Héctor VARGAS, Elba México Instituto Nacional de Cultura (Trujillo-Lima) — TEYSSIER, Esperanza del Perú Zona Arqueológica de Teotihuacán México En calidad de oyentes asistieron igualmente represen- tantes de las instituciones siguientes: Perú Also present as auditors were representatives of the —MACH I CAO, Leonidas following institutions: Colegio de Arquitectos del Perú — TORRES, Rafael Argentina Colegio de Ingenieros — Dirección de Arquitectura del Perú de la Provincia de Jujuy —GALLEGOS, Héctor IN IAVI Chile —TAKIZAW A , Juan —SANTOLALLA, Javier — Instituto de Investigaciones Instituto de Investigación Arqueológicas y de Restauración y Normalización de la de Monumentos Vivienda Universidad de Antofagasta — PA LACIOS, Alberto Servicio Nacional de Ecuador Capacitación para la — Concejo Provincial Industria de la de Pichincha Construcción (SENCICO) — BARRI OLA BERNA LES, Juan Perú Pontificia Universidad Católica del Perú — Municipalidad de Lima —CORREA ORBEGOSO, José — Concejo Provincial ARIES de Cajamarca

147 General Supervision: Sylvio Mutal Translation: Fanny Meerovici y Juana Truel Editor: Juana Truel Graphic Design: Yolanda Carlessi Photos: Mario Acha, Yolanda Kodelja and File Cover Photograph: African adobe arquitecture. File: Center of Applied Technology, Bamako, Mali Back Cover Photograph: Paramonga Fortress, north coast of Peru File: National Aerophotographic Service Printer: INDUSTRIALgreifica S.A.

148 iviC 4- r.44.4.44041" NN. 4.1 ire; S;IA..r1 o.

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