Roller Compacted Concrete Mix Design For Dams

Properties of roller compacted concrete mix design.

Roller compacted concrete mix design for dams.

The development of roller compacted concrete rcc was a major change in the construction practices of dams and other structures. The soil compaction method consists of the following steps. The overriding criteria for these mixtures are the shear strength between the lifts and low permeability of concrete since no protective impermeable face is used upstream. Upper still water and elk creek dams are examples of dams that were built using this approach.

Over the past two decades many design details and construction methods have been adapted to enhance the final product while maintaining the speed of construction that provides rcc its competitive edge. Roller compacted concrete rcc was originally limited to the sub base of roads and airfield pavements being called lean concrete or dry lean concrete. Roller compacted concrete is defined as the concrete which is compacted by roller compaction technique. Mix design proportioning methods for no slump concrete applicable for roller compacted concrete.

Materials used in rcc mix design a cementitious materials. Whereas a roller compacted concrete pavement built to replace a failed pavement on a major route may require reaching 2 500 psi compressive strength and be opened for traffic within one or two days from placement. In the quarter century since willow creek considerable research and experimentation have yielded innumerable improvements in concrete mix designs dam designs and construction methods for roller compacted concrete dams. This proportioning method involves establishing a relationship between the density and moisture content of an roller compacted concrete mixture to obtain the maximum density by compacting samples over a range of moisture contents.

Mix design proportioning methods for roller compacted concrete rcc. The mix design of rcc usually consist of a high amount of stone portland cement with a replacement of fly ash a minimal amount of sand and of course water to hydrate the mix. The concrete mixture used for construction should keep in an unhardened state to support the roller compaction. This type of concrete has become very popular due to the fact that it is a simple material to produce and because it can be placed fast while producing a great surface.

By 2008 about 350 rcc dams existed worldwide. Roller compacted concrete rcc continues to gain recognition as a competitive material for building new and rehabilitating existing dams. Currently the highest dam of this type is the gilgel gibe iii dam in ethiopia at 250 m with the pakistani diamer bhasha dam. Different mixes of roller compacted concrete can be designed to meet the different requirements of the two applications.