Abstract:
The chloride attack environment with cyclic drying-wetting ratio of 3 : 1 and 5wt% mass fraction of NaCl solution was simulated to conduct the chloride ingress test of recycled aggregate concrete (RAC) with diffe-rent replacement rates (
r=0%, 30%, 50%, 100%) subjected to sustained compressive loading and drying-wetting cycles. Effect of different sustained compressive stress levels (
λc=0.1, 0.3, 0.5) the chloride ingress performance of RAC was studied. Based on the chloride convection-diffusion model of unsaturated concrete, the models of water diffusivity and chloride diffusion coefficient considering the effects of recycled coarse aggregate replacement rate and stress level were proposed and validated. The results indicate that at the same replacement rate of recycled coarse aggregates, the free chloride content, chloride diffusion coefficient and surface chloride concentration in RAC decrease first and then increase with the increase of sustained compressive stress level. Under the same stress level, they are positively correlated with the replacement rate of recycled coarse aggregates. The chloride diffusion coefficients of specimens with the replacement rate of 100% subjected to 0.1
fc, 0.3
fc and 0.5
fc (
fc means the cubic comprssive strength of RAC) are 0.97, 0.88 and 1.48 times than that of unstressed state, respectively. The established model of the chloride ingress in RAC under sustained compressive loading and drying-wetting cycles can partly provide the theoretical basis for the durability of RAC.