Properties of Concrete Containing Reclaimed Concrete Aggregate of Controlled Quality

摘要

The need to reuse reclaimed or recycled concrete aggregate (RCA) in concrete has increased over the years due to the depletion of virgin aggregate sources. The use of RCA will reduce the accumulated demolished concrete waste in landfills as well as decrease the energy consumption that would be needed to mine and transport new virgin aggregate. The research presented in this paper examines the use of RCA of controlled quality to produce concrete for different classes of exposure. Currently, water is used to ease the dumping process of return-to-plant concrete. This increases the water content in the dumped concrete which weakens the produced RCA. The practice adopted in this paper involved limiting the amount of added water and separating the retuned concrete based on strength and air entrainment. Concrete containing 0%, 30% and 100% coarse RCA was produced in the laboratory. Mix designs included concrete with a water to cement ratio of 0.62 and non-structurally reinforced concrete exposed to chlorides and freezing and thawing (C2 concrete according to CAS 23.1). Compressive strength and free shrinkage were tested on concrete containing RCA and virgin natural aggregate of varying quantities in a controlled environment.