International RCC Symposium reviews design and construction technology CONFERENCE REPORT R. Ibáñez de Aldecoa, Dragados USA, and SPANCOLD, Spain F. Ortega, FOSCE Consulting Engineers, Germany and SPANCOLD, Spain Since 1991, two pioneering and leading countries in RCC technology, Spain and China, have been combining their efforts to organize the RCC International Symposia, with a wide range of contents and worldwide scope. Last autumn, the state-of-the-art of RCC dam design and construction was reviewed comprehensively during the three-day 6th International Symposium on Roller Compacted Concrete in Zaragoza, Spain, updating the knowledge attained at the five previous events in this series. Opening of the his sixth Symposium followed those held in Technical Exhibition Beijing (China) in 1991, Santander (Spain) in by Ms Liana 1995, Chengdu (China) in 1999, Madrid (Spain) Ardiles, General in 2003, and Guiyang (China) in 2007. About 350 del - Director of Water at Tegates from 40 countries gathered for the event, which MAGRAMA. was organized by the Spanish National Committee on Large Dams (SPANCOLD), the Chinese National Committee on Large Dams (CHINCOLD), the European Club of ICOLD and the Spanish Institute of Cement and its Applications (IECA), in collaboration with the Spanish Ministry of Agriculture, Food and Environment, and ICOLD. The Symposium was attended by ICOLD President Adama Nombre, as well as the President of SPAN - prepared by CHINCOLD and SPANCOLD members, COLD, José Polimón, and Hon. President of ICOLD and a general update of the technique by Dr Malcolm and Vice President and General Secretary of CHIN - Dunstan of UK. COLD, Jia Jinsheng, the latter heading a large delega - The Opening Session, see photo below left, was tion from China. chaired by Ms Liana Ardiles, General Director of A total of 104 papers from 27 countries were accept - Water at the Ministry of Agriculture, Food and ed and published in the Proceedings, together with the Environment (MAGRAMA), who later also chaired seven special lectures given by eminent international the Opening of the Technical Exhibition, see photo experts on RCC dams. A significant number of the above. accepted papers were presented during the technical The technical quality of the Symposium was sessions. enhanced by the fact that experts from all the pioneer - Symposium attendees also received a CD with an ing and leading countries in RCC dam design and con - update on the RCC chapters of the Technical struction had assembled to exchange experience and Guidelines for Dam Safety published by SPANCOLD, report on progress in their respective countries. to increase the distribution of these Guidelines and to As part of the Symposium, the existing agreement demonstrate the high level of RCC technology in between the Spanish and Chinese Committees was Spain. Also, a complimentary copy of Issue 5, 2012, of extended for another three years, to continue the trans - Hydropower & Dams was distributed to all partici - fer of technology and knowledge in the field of dams pants, which included several articles related to RCC between these two countries. In the Closing Session, with the support of ICOLD, to recognize major achievements in RCC dam tech - nology and to define milestone projects in this field, International Milestone Awards were given to three recent RCC dams. This was the second time that these prizes had been granted, following those given in Guiyang in 2007. A three-day post-Symposium Study Tour was arranged, departing from Zaragoza and ending in Bilbao, to connect with HYDRO 2012 organized by Hydropower & Dams . 1. Special presentations and lectures A total of seven special lectures on various aspects of RCC dams were given throughout the symposium by The Opening Session of the RCC Symposium in Zaragoza on 23 international experts. The main topics were as fol - October. lows. Hydropower & Dams Issue Three, 2013 1 Dr J.C. de Cea, General Secretary of SPANCOLD, during his special lecture on RCC dams in Spain. 1.1 RCC dams in Spain Dr Jia Jinsheng, Honorary President of ICOLD, during his The design philosophies, construction methodologies special lecture on RCC and CMD dams in China. and essential characteristics of the 28 RCC Spanish dams that are currently in operation (27) and under However, the latest tests carried out at the beginning of construction (1) were summarized in this lecture, by construction of the 102 m-high Enciso RCC dam, with Dr J.C. de Cea of Spain, see photo above. He pointed a very workable and super-retarded mix, were very out that his country has a large tradition in RCC dams, successful in showing the efficiency of the direct with the first RCC experience dating back to 1984. immersion vibration of RCC without any additional De Cea’s comparative description of Spanish RCC grout (IVRCC). Preliminary results of these tests indi - dams focused on several particular aspects, such as the cate that a significant step forward has been made typical cross section, imperviousness, materials and towards the improvement of the in-situ quality and the mixes, transverse and horizontal joints, construction general behaviour of RCC dams. aspects, test sections, other uses and behaviour. Delegates heard that the largest RCC dam in Spain is 1.2 RCC and CMD dams in China La Breña II, see photo below, with a maximum height × 6 3 of 119 m and a total concrete volume of 1.60 10 m . China is undoubtedly the world-leader in RCC dam La Breña II, completed in 2008, is also the largest construction. A total of 157 RCC dams (30 per cent of RCC dam in Europe. the total) have been built or are under construction in Spanish RCC dams have followed the main princi - the country. The world’s highest RCC dam is ples of simplicity in design and a high content of Guangzhao (200.5 m high), which was completed in cementitious materials in the mix proportions (average 2009. Seven RCC dams in China are higher than 3 of 210 kg/m ). The cementitious materials used are 150 m, and there are 12 arch-type RCC dams higher mainly cement and flyash class F. The imperviousness than 100 m. The highest of these is the Wanjiakouzi View of La Breña II RCC arch dam, which is under construction at present RCC dam (119 m of these dams is achieved by the high quality of the high, with an RCC mix itself, and appropriate specification of the con - and will have a total height of 160.5 m. × volume of 1.44 struction procedures. Developments and improve - Experience and design principles for RCC dams high - 10 6m3) completed in ments in the technology have been quite evident in er than 200 m were reviewed in a special lecture by Dr 2008 in Spain. It is Spain. In recent projects, the interface concrete against Jia Jinsheng of China, see photo above. In particular, the largest RCC the formwork and abutments has been some kind of the research on high water pressure fracturing was pre - dam in Europe. enriched RCC (enriched by either grout or mortar). sented as a key aspect requiring special attention, to evaluate the safety of future high RCC dams. The second part of Jia’s presentation focused on the Cemented Material Dam (CMD) and its application. The rockfilled concrete (RFC) technology that was used for the reinforcement works of the 69 m-high Hengshan arch dam in China, as discussed by Dr Jia Jinsheng. 2 Hydropower & Dams Issue Three, 2013 Dr M.R.H. Dunstan during his special lecture, ‘New developments in RCC dams’. This concept aims to build on previous design experi - ence such as CSG, hardfill, masonry and rockfilled concrete (RFC) dams. CMD has been created to pro - mote safer and faster construction, with low investment costs and based on environmentally friendly technolo - The highest, largest (by volume) and fastest ten com - Distribution and gy. Various forms of composite concrete construction pleted RCC dams are listed in this paper for reference. design philosophy of materials are used under this new concept of optimiz - The dams with the best-reported in-situ properties are RCC dams around ing the dam structure, to make a better use of local also included. As a conclusion the importance of the the world (2011), materials. RCC dams have developed towards tradi - reported by Dr rate of placement based on the simplicity of the design M.R.H. Dunstan. tional concrete dams in many respects and CMD can be was emphasized by Dunstan as an important goal for considered as a dam type which is somewhere between the success of future RCC dams. a rockfill and concrete dam. The concept seems to have been accepted rapidly for application for small and 1.4 Innovations in RCC dams medium-sized dams in China. This lecture, by B. Forbes of Australia, included refer - 1.3 New developments in RCC dams ence to significant innovations that have been adopted on RCC dams recently, which in the author’s opinion Following a series of papers presented at the previous provide for improved quality, more efficient construc - RCC Dam Symposia, an extension and update of data tion and reduced costs. Besides traditional topics such had been prepared for this 6th Symposium by Dr as the advantages and disadvantages of the sloped M.R.H. Dunstan of the UK. His paper traced the layer construction procedure and the use of grout- changes that have taken place over the 20 years since enriched RCC (GE RCC) in place of conventional the first Conference (Beijing, 1991) in terms of the dis - vibrated concrete, some recent new approaches and tribution of RCC dams around the world, the expan - procedures had been introduced, Forbes pointed out.