Saco Dam—South America's First RCC Dam

Because of cost and a lack of suitable embankment materials, Saco Dam at Nova Olinda in Paraiba, Brazil, was redesigned and built with lean roller compacted concrete (RCC). The structure uses a gravity section with a formed 0. 8 to 1. 0 (h:v) downstream slope, a conventional concrete upstream face placed monolithically with the RCC, an upstream bedding mix for seepage control, a curved axis necessary to accommodate the natural terrain, and a mined gallery. Detailed analyses were made for thermal cracking of the mass and for thermal cracking with drying shrinkage stresses added for the upstream face. Cracks that occurred in the facing after construction had started without joints verified the depth and frequency that had been predicted. Successful actions were then taken to control subsequent cracking, including mix adjustments and addition of joints only in the upstream zone. Initial performance of the dam including seepage is discussed.