Effects of Chloride Binding and Electrode Processes on Multi-Ion Transport Modelling of Migration Test in Low-Clinker Concretes

Abstract

This study proposes multi-ion modelling of chloride migration within low clinker–based cementitious materials. It discusses the effect of the electrode processes on chloride migration, the chloride binding isotherms and the chemical activity calculated from different models. For this purpose, we used the proposed model to simulate the standard chloride-migration test in the steady and non-steady states. The simulations showed that chloride-migration kinetics and the chloride front are mainly impacted by the chloride-binding isotherm as a function of the studied material. There was a difference of up to 17% in the time to reach the steady state during the chloride-migration test when two different chloride-binding models were used. Electrode processes, which are responsible for the electroneutrality of the system, also impacted chloride migration: there was a difference of 6% in the chloride concentration when considering electrode processes. The effect of chemical activity was negligible, regardless of the model used for calculation.

Keywords: Cementitious materials, Chloride migration, Modelling, Electrode processes, Chloride binding isotherms