Experimental and computational modeling of chloride transport behavior in fully recycled coarse aggregate concrete

Abstract

Exploitation of recycled coarse aggregate (RCA) aimed to produce fully recycled coarse aggregate concrete (FRCAC) has attracted more attention due to the growing requirements for sustainable development and carbon neutralization. In this paper, a novel computational model is developed to study the chloride migration behavior in FRCAC at the mesoscopic level. RCAs are generated by a random convex polygon algorithm to approximate the realistic arrangement, shape and polyphase components of aggregates. FRCAC with different RCA volume fractions (0 %, 20 %, 35 % and 50 %) was made by the optimized triple mixing method (OTM), and its chloride transport behavior was investigated by drying-wetting cycles test exposed to sodium chloride solution (50 g/l) for 250 days. The experimental results demonstrate that the transport depth and concentration of chloride increase with the augment of the RCA volume fraction. The availability and universality of the present computational model were validated by comparing with the experimental data. The numerical results show that RCA has both adsorption and barrier effects on the chloride transport, which makes the chloride isoline bend and the flow direction change. Finally, it is demonstrated that chloride diffusivity in 2D case increases compared with 1D case. The findings of presented study can better enhance the understanding of the chloride transport mechanism in FRCAC at mesoscopic.