Building techniques : A2 – Dressed Quarry Stone Wall Coutry: Lebanon PRÉSENTATION Geographical Influence Definition Dressed quarry stone wall - traditional masonry tools: chisel, picks and hammers. - 4, 5, 6 faces-sometimes 2 faces - naturally squared. - stone laying with or without wedging. - stones are laid straight, same size or not. - mortar laying Environment In the MEDA area, we find dressed quarry stone in all environments: urban, rural, in mountain, plain and sea side. Its presence is generally common. In Lebanon, dressed quarry stone (Moqassab) is often used everywhere: rural environment, urban, plain, mountain and sea side. Illustrations General view: Details close-up: This project is financed by the MEDA programme of the European Union. The opinions expressed in the present document do not necessarily reflect the position of the European Union or of its member States. 1/8 A2 Lebanon – Dressed quarry stone wall CONSTRUCTION PRINCIPLE Foundations Illustrations Finding a "firm base" or “good ground” is a preliminary for the builder. If rock shows on the surface, the wall is built directly above. If not, all countries dig a small trench (~ 50 cm deep), practically never deeper than 1m. the width can be equal to the thickness of the wall above-ground, but it can also be up to twice this thickness. Combination of 2 factors : width of the trench and type of filling materials: adjustments and adaptation to each spot and ground. The materials are always stony: the trench is filled with stones, generally linked with mortar. If the module is small, the trench is broader. Several countries reported construction over ruins used as foundation. In Lebanon, dressed quarry stone walls are built either directly on rocky ground, or a trench is dug if the ground is loose. The foundation is filled with a coarser rough stone masonry, laid in mortar, slightly broader than the thickness of the wall, and reaches solid ground level. Construction Materials Type and hardness To build dressed quarry stone walls, you must avoid using stones that might flake. The first quality for stones is also that they be easy to cut and face : that is why limestone is commonly used in the thirteen studied countries. It is usually semi hard, around five on a scale from 1 to 10. (1=chalk, 7 to 8= marble, 10=granite ). After limestone, we find basalt (Cevennes in France, the Jordan Valley in the Middle East) and finally sandstone (in Spain, France, Tunisia), or granite. In Lebanon, for dressed quarry stone constructions, limestone (reported hardness: 4 to 6), basalt in the areas of Akkar, or dune sandstone "Ramleh" in certain Littoral zones. The hardness of limestone depends on the origin and extraction depth of the limestone used, filled with earth and rubble (gravel...) for walls with two linked facings. Modules Modules of all sizes can be found. Thus, throughout the Mediterranean area, blocks are 12 to Construction principle: materials and 80 centimeters long, 8 to 40 cm high and 15 to 60 cm deep. Blocks may vary substantially in modules. View of building boat in dressed volume from 2 liters to 100 liters. These blocks can non-the-less be handled by a few men. quarry stones This being an important characteristic for dressed quarry stone walls (rough for dressed quarry ) as opposed to six faced ashlar. The following correlation has been observed : large modules are usually soft stone and not very dense (Israel = 80 x 30 x 40, hardness 3), small modules are harder and heavier stones. In Lebanon, the dimensions of dressed quarry stones are: length, between 20 and 70 cm (variable); course height, between 24 and 30 cm; depth, between 20 and 35 cm. Mortar laying Realisation / Construction : Dressed quarry stone walls are always laid in mortar. The ingredients generally found are: lime + sand (sometimes + gravel or + broken tile or + crushed stone powder), earth + straw, earth alone. In Lebanon, dressed quarry stone masonries are laid in mortar with lime mortar. Binding material : Detail of material The two binders used for the realisation of dressed quarry stone masonry throughout the studied countries are either lime, or earth. In Lebanon, the binding material used for the mortar of dressed quarry stones is lime. Agregate – grading : The aggregates are sand, gravel, broken tile and coarsely or finely chopped straw. In Lebanon, the aggregates used for the mortar of dressed quarry stones are sand, earth and gravel. Ashes and broken tile are sometimes also added. Dose ratio : The grading of these aggregates varies according to kind from 0-3 mm to 0-12 mm. In Lebanon, the reported dose ratio for the mortar of dressed quarry stones is of one volume of binding material for 3 volumes of aggregates. Associated element This project is financed by the MEDA programme of the European Union. The opinions expressed in the present document do not necessarily reflect the position of the European Union or of its member States. 2/8 A2 Lebanon – Dressed quarry stone wall CONSTRUCTION PRINCIPLE (CONTINUED) Mortar laying (continued) Illustrations Dose ratio : One volume of mortar contains from 15% to 50 % of binding material, lime or earth. Fat mortar can be used (40% to 50% of binding material in the composition), depending on the aggregate used: if only one type is used, and if it is fine, than the volume of mortar binding is increased. Exceptionally, a second or third aggregate can be added to thin down the dose ratio (20% to 33%). In this case the aggregate grading is more elaborate and integrates fine elements (stone powder, ashes), average size elements (sand, broken tiles) and large elements (gravel, chopped straw). This art of combining inert mass materials saves on binding material and optimises its use. For modest buildings, cradling mortars are usually more slack than for facings: they are not measured out as precisely and earth usually partly replaces lime. This is obviously done for economical reasons. In Lebanon, the reported dose ratio for the mortar of dressed quarry stones is of one volume of binding material for 3 volumes of aggregates. Thickness and Dimensions This construction technique leads to building thin walls: 25 cm (exceptional) to 45 cm, and very thick walls, 45 cm to 100 even 120 centimeters. In the first case, the stones on each facing of the wall are fitted one against the other, alternating one long with one short. In the second case, for thick walls, the stone facings are separated with filling. This filling can be made of smaller elements of the same type: rubble, quarry waste, broken tiles or broken bricks etc., or mortar alone. Sometimes header binder will joint two facings more efficiently. Sometimes the builder makes the wall wider at each floor level. This traditional type of wall makes it possible to construct substantially high buildings (16 m or Construction principle: wooden lintel more). The corresponding thickness can vary by 10% (60 centimeters for 6 m in height ) up to 50% (75 cm for 15 m in height). Up to four levels, 60cm are enough, beyond we find a thickness of 80 to 120 cm. Common constructions do not have more than six levels. Greater heights are exclusively found in urban areas. In Lebanon, the technique of dressed quarry stone walls consists in building masonries whose thickness varies from 40 to 60 cm for the single linked facing walls, and between 60 and 120 cm for double linked facing walls. In the case of double linked facing walls; the two facings are linked with an intermediate filling: a mixture of lime mortar and more or less large aggregates. Header binder stones are laid to ensure the linking of this two row masonry. The maximum height of dressed quarry stone constructions on one level is approximately 4 m for simple walls. The height is variable for the double linked facing walls. It depends on the type of associated floor. The thickness of a wall associated to a metal beam floor out is around 60 cm, whereas it easily reaches 100 cm when the wall is associated to a vault. Finishing Aspect There are four possible finishing coatings: keeping the wall bare either as constructed or joint, wall slightly lime-washed, wall totally covered with rendering and finally wall with rendering and lime-wash. There are two distinct reasons for choosing finishing coating: The first is aesthetic : giving priority or not to the regularity and homogeneous aspect of the Windows and openings facing leads to leaving the wall bare, painting or rendering it. Deciding to leave the wall bare depends on whether the quality of the material is suitable or not. The second reason is practical. The rendering is a means of protection for the facing of the wall. The choice noticed today is not necessarily the original one, it may have varied in time through restoration campaigns led for maintenance reasons or influenced by style and fashion. This kind of wall is finished with lime, earth or a combination of lime and earth. Lime washing is usually made with lime, sometimes tinted with color. In North Africa, plaster and white clay are sometimes used. In Lebanon, dressed quarry stone masonries have rather regular courses, and are generally left bare. They are only pointed. The external walls can be pointed, and then washed with lime. The interior walls are rendered with earth or lime and then whitewashed with lime. Associated element: niche This project is financed by the MEDA programme of the European Union. The opinions expressed in the present document do not necessarily reflect the position of the European Union or of its member States. 3/8 A2 Lebanon – Dressed quarry stone wall CONSTRUCTION PRINCIPLE (CONTINUED) Tools Masons use traditional tools for building this kind of wall (wheel barrow , trowels, brush, plumb line, chisels, float, drift pins etc.), no other specific tool has been reported.