Prediction of Equivalent Steady-State Chloride Diffusion Coefficients

This paper presents an approach for determining the chloride migration rate of hardened concrete by applying fundamental electrochemistry for different cementitious mixtures using the measurements from the chloride-ion penetration test (CIPT) data following ASTM C1202 specifications. The steady-state condition is verified by comparing the numerical values of chloride migration rates during 5, 30, and 360 minutes of testing. Three different theoretical approaches-Nernst-Plank, Nernst-Einstein, and the Zhang-Gjorv method-were applied to obtain the equivalent steady-state diffusion coefficients for different cementitious materials. These results are compared with the diffusion coefficients obtained from Berke's empirical equation using CIPT data. These methods for the computation of diffusion coefficients include both the joule effect and temperature dependency and eliminate the need for other extended migration tests to obtain the steady-state conditions. Overall, this research presents a reliable method of determining the chloride migration rate for diffusion coefficient prediction.