The relationship between steady-state chloride diffusion and migration coefficients in cementitious materials

Abstract

The chloride diffusion coefficient is directly related to the property of concrete to resist the ingress of chloride ions and it is a decisive factor for the durability of reinforced concrete subjected to the chloride environment. The conventional chloride diffusion test requires considerable time to attain a steady-state chloride flow across the specimen. Therefore, the rapid chloride migration test is frequently employed with an applied electrical field to accelerate the chloride transport. However, the chloride diffusion coefficient estimated based on the rapid chloride migration test is different compared to the actual chloride diffusion coefficient. In this study, a theoretical model of the relationship between the steady-state chloride diffusion coefficient and chloride migration coefficient has been obtained for cementitious materials. Based on the theoretical model, an empirical model of the relationship between steady-state chloride diffusion and migration coefficients is proposed for cementitious materials. Furthermore, the parameters of the empirical model were obtained through the results of chloride diffusion and migration tests on a range of mortar mixtures made with ordinary Portland cement and blended cements with additions of ground granulated blast furnace slag, pulverised fuel ash and silica fume, and the published data from other researchers.