Construction methods for roller-compacted concrete spillways

Roller-compacted concrete (RCC) is now an accepted method for constructing spillways. The design, materials properties of RCC, and construction methods are still evolving. The U.S. Department of the Interior, Bureau of Reclamation (Reclamation) has constructed five service and emergency spillway structures, each demonstrating the developing state-of-the-art in RCC construction. All five spillways were constructed concurrently with other extensive dam safety modifications. These spillways were constructed with side-slopes ranging from 0.8:1 to 2.5:1 (horizontal to vertical). The spillways used different methods for batching, mixing, transporting, placing, and compacting the RCC. The RCC was mixed in both continuous mixing and conventional batching plants. End dump trucks, front-end loaders, conveyors, and track-hoes transported RCC. Various methods were tried to compact the unformed, outside edges of these differing side slopes. 14 pp., 1 table, 6 figures, 9 references.