BACKGROUND ON ROLLER-COMPACTED CONCRETE
To achieve a successful project, it is important that the specification writer distinguish RCC from conventional concrete, and apply the provisions of this specification that are most appropriate for their application. RCC is essentially portland cement concrete. However, it is engineered and constructed differently than conventional concrete and requires different placement and design considerations even though it is made of the same constituent materials: aggregate, portland cement, supplementary cementitious materials, chemical admixtures and water.
Although made of similar materials, RCC pavements are unlike conventional concrete pavements in many ways, especially during production and placement. Therefore, it is important for the specification writer to be keenly aware of these differences while developing
RCC specifications, including:
RCC requires placement with aphalt-type pavers. It is not placed with typical slipform concrete paving machines.
RCC mixtures require compaction with the use of vibratory, tamper bar screeds, and subsequently, with vibratory rollers to achieve a target density.
RCC does not require the internal vibration necessary to consolidate conventional concrete.
RCC has little to no slump. Conventional concrete paving mixes require between 1-in (0.25 mm) and 4-in (100 mm) of slump depending on placement method.
RCC mixtures require different mixing considerations than conventional concrete mixtures.
RCC mixtures are relatively dry compared to conventional concrete mixtures and depend on stability in the plastic state to support rollers for compaction.
RCC mixtures do not usually require air entrainment for freeze/thaw durability. The experience from past projects indicate that it is not necessary, however additional study is continuing.