Influence of natural coarse aggregate type on the transport properties of recycled concrete

Abstract

The use of recycled concrete represents a friendly environmental solution for minimizing the impact of construction and demolition wastes. In many countries, the incorporation of recycled coarse aggregates (RCA) is a common practice, the maximum contents of RCA being usually limited to around 25% of the total coarse aggregate content. The incorporation of higher volumes of RCA is a field of discussion mainly regarding the durable behaviour of concrete. This paper analyses different transport properties of 20 to 50 MPa compressive strength concretes prepared with variable contents of RCA (0%, 25%, and 75%). Eight types of RCA were obtained from concretes incorporating four different natural coarse aggregates: granitic, basaltic, and quartzitic crushed stones and siliceous river gravel. Capillary absorption, water penetration and chloride diffusion tests were done. The variation of transport properties with concrete compressive strength and the effect of RCA content on the variability of transport properties were analysed. According to the results obtained, the durable behaviour of recycled concretes will be different according to the transport mechanisms to which they are exposed and it can be as good as that of concretes made with natural coarse aggregates.