Eco-efficient low cement recycled concrete aggregate mixtures for structural applications

Abstract

Research has shown that good quality recycled concrete aggregates (RCA) can be produced for structural applications if the aggregate properties are properly considered in the mix design, especially the residual mortar content (RMC). Previous studies on RCA have generally used mixes with moderate to high cement contents, which negates many of the environmental and economic advantages of this material. In this study, the equivalent mortar volume (EMV) method was used to develop RCA mixes with the aim of minimizing new cement content by accounting for the RMC already present, thus improving binder efficiency. Conventional RCA mixes (i.e. 25 and 35 MPa compressive strengths) containing low cement content were developed without any chemical or mineral admixtures. A modified EMV method was proposed to overcome challenges encountered in the fresh state and an optimized 35 MPa mix was developed with a low binder intensity of 9.2 kg/m3·MPa−1.