Structural Performance and Finite Element Modeling of Roller Compacted Concrete Dams: A Review

Abstract There is no doubt that concrete is one of the most consumed materials all over the world. It is a composite mix widely used for constructing structures and infrastructures to sustain environmentally induced stresses such as thermal and seismic. As the mainstream of construction industry is tended to find out feasible solutions, Roller Compacted Concrete (RCC) was introduced to play an essential role in the development of dams and pavements, where over 550 RCC dams were created by the end of 2012. In fact, this material has the same basic constituents of conventional concrete with a zero-slump and a significant difference in the placing process. The majority of available studies in the literature are composed of numerical investigations to assess the thermal and seismic behavior of RCC dams and to provide a clear view on how to improve its performance under various loading conditions. This paper summarizes and compares the general conclusions of recent works on evaluating the structural performance of RCC dams

Effect of heat generation from cement hydration on mass concrete placement

Construction of a concrete dam requires large volume of concrete. Due to the small surface area-to-volume ratio, concrete dams are often subjected to high potential of thermal cracking, caused by the heat generation from cement hydration. To reduce the thermal cracking and ensure dam structure safety, a concrete dam is often constructed with low heat-generating cement and separated blocks having relative thin lift thickness. In Korea, low heat Type IV has been mainly used to reduce the temperature rise. Although benefits of using supplementary cementitious materials (SCMs) in concrete have been recognized, the practice of SCMs in dam concrete is not very common due to a concern for safety. On the other hand, increasing lift thickness of concrete blocks to accelerate dam construction has always been a demand. The purpose of this research is to explore the potential use of fly ash as Type IV cement replacement in Korea concrete dams and to determine the proper lift thickness of concrete blocks in dam construction. In the present study, the chemical compositions and fineness of cement and fly ash are characterized. The heat hydration of fly ash replacement for Type I cement and Type IV cement are studied and compared. The temperature distributions and thermal cracks of a concrete block having four different lift thicknesses (1.5m, 2m, 2.5m, 3m) are analyzed using FEM commercial software ANSYS. The results indicate that 40% fly ash replacement for Type I cement shows a similar heat generation and compressive strength at 28 days with that of Type IV cement and also has cost savings of 25%. A lift thickness equal or less than 1.5m showed little potential for thermal cracking. Construction placement with a lift thickness greater than 2m had high probability of thermal cracking