Report on Roller-Compacted Mass Concrete

Description

Roller-compacted concrete (RCC) is probably the most important development in concrete dam technology in the past quarter century. The use of RCC has allowed many new dams to become economically feasible due to the reduced cost realized from the rapid construction method. It also has provided design engineers with an opportunity to economically rehabilitate existing concrete dams that have problems with stability and need buttressing in addition to improving existing embankment dams with inadequate spillway capacity by providing a means by which they can be safely overtopped .

RCC has allowed new embankment dams to optimize spillway capacity in over-the-embankment-type emergency spillways (Hansen 1992).This document summarizes the current state of the art for design and construction of RCC in mass concrete applications. It is intended to guide the reader through developments in RCC technology, including materials, mixture proportioning, properties, design considerations, construction, and quality control and testing. Although this report deals primarily with mass placements, RCC is also used for pavements (refer to ACI 325.10R) and for dam stability improvement and as embankment dam slope protection (United States Society on Dams 2003).

ACI Concrete Terminology (2010) defines roller-compacted concrete (RCC) as “concrete compacted by roller compaction; concrete that, in its unhardened state, will support a roller while being compacted.” RCC is usually mixed using high-capacity continuous mixing or batching equipment, delivered with trucks or conveyors, and spread with bulldozers in layers prior to compaction with vibratory rollers (Fig. 1.1).

Because of RCC’s zero-slump consistency, subsequent lifts can be placed immediately after compaction of the previous lift. RCC can use a broader range of materials than conventional concrete, and derives its strength and durability from a mixture philosophy that relies on using just enough paste volume to fill the aggregate voids and no more water content than what is needed for proper workability