Chloride diffusion and binding capacity in concrete suffered from ASR

Experiments were conducted to investigate the chloride diffusion and binding capacity of concrete suffered from both ASR (alkali-silica reaction) and chloride ingression. Two levels of ASR were set by adding different amount of alkali in concrete, and the ASR was accelerated by heating. Two sodium chloride solutions of various concentrations were used to ingress the concrete simultaneously. The contents of free and total chloride ion in the concrete specimens of various depths were measured after different exposure periods. The structures of some specimens were analyzed by XRD (X-ray diffraction), SEM (scanning electron microscopy) and MIP (mercury intrusion porosimetry). The results show that the diffusion rate of chloride ion is alleviated in the existence of ASR. The binding capacity of chloride in the concrete with ASR is much lower than that in the concrete without ASR. The crack induced by ASR does not promote the ingression of chloride significantly. The results suggest that in the concrete structure susceptible to ASR, the inclusion of chloride can speed up the chloride erosion because of the low capacity of chloride binding. And the chloride in surroundings, although diffuse slowly into concrete, can corrode the reinforcement in concrete in the long run.