Steady-State Chloride Diffusion Coefficient and Chloride Migration Coefficient of Cracks in Concrete

Abstract

Prediction of chloride ingress is very important for the durability of reinforced concrete structures in chloride-laden environments, especially for concrete with cracks. It is expected that the chloride diffusion coefficient of a crack is much higher than that of the uncracked part in concrete. A single crack in concrete can be a shortcut for chloride ions to pass through. Research on chloride diffusion/migration through cracks in concrete is limited. Therefore, in this paper steady-state chloride diffusion and migration coefficients of cracks in concrete were measured and calculated and the relationship between the two coefficient types was analyzed theoretically and compared with experimental data. The results show that the ratio between the two sets of diffusion/migration coefficients can be related to the ratio between the specimen length and crack length. The measured crack length depends on the resolution of the sampling by microscopy. The optimum unit sampling length for the crack length measurement was found be close to the value of crack width.