Theoretical study of methods used to determine ionic diffusion coefficients in concrete using migration tests

Abstract

In this paper, we numerically simulate migration experiments using the Nernst-Planck (NP) equation coupled with the electroneutrality condition (EN) by means of finite element analyses. Effects of applied voltage difference and chloride source concentrations on chloride diffusion coefficients are presented. Migration due to the non-linear electric potential effectively overwhelms diffusion due to concentration gradients. A comparison between diffusion coefficients obtained from sophisticated analyses (i.e., NP-EN) and a variety of commonly used simplifying methods to estimate chloride diffusion coefficients is made. Based on this comparison we identify appropriate experimental conditions whe..