A Gravity Dam is made of soil, rock, concrete or masonry. For soil and rock dams, see embankment dams. It’s the sheer weight of the structure that holds it down to the ground resisting the horizontal pressure of water pushing against it. This kind of dam, in cross-section view, appears roughly triangular. Gravity dams are suitable for both wide or narrow valleys, but since they rely on their own weight to hold back water, it is necessary that they are built on a solid foundation of bedrock.
Concrete dams are gravity dams usually built in large blocks divided by joints to make the construction more convenient and reduce thermal stress. The joints are grouted after the dam is cooled. Transverse joints are perpendicular to the dam axis. A concrete dam is a major construction project that needs a massive amount of concrete, resulting in the use of a large amount of cement. Cement production is causing CO2 emissions that are detrimental to the environment and is also a high-cost procedure.
Roller Compacted Concrete (RCC) dams are made of a composite construction material with no-slump consistency in its unhardened state. RCC is made from a mix of cement/fly ash, water, sand, coarse aggregate, and common additives, but contains much less water compared to conventional concrete. This kind of drier concrete is able to support a vibratory roller, in its unhardened state, during the compaction. The usage of low cement content and fly ash causes less heat generation while curing compared to conventional concrete. RCC dams are usually built in thin, horizontal lifts resulting in rapid construction.