Modelling of chloride penetration in unsaturated concrete

Abstract

In this paper, a new model is proposed to describe the coupled transport of ionic species and ionic solution in unsaturated concrete. The main difference between the present model and most existing models is the inclusion of osmotic effect due to small pore sizes and osmosis-flow due to electrochemical reactions taking place at two electrodes. Chemical- and electro-osmosis is a well-known phenomenon in soils and clays. Cement and concrete materials, whose microscopic properties are very similar to clays, are expected to have a similar behaviour. However, despite the large amount of work that has been published on the osmosis of soils and clays, there is very little work on the cement and concrete materials. The aim of this paper is to address this problem. The model proposed in the paper is applied to predict the chloride penetration in unsaturated concrete and the electrochemical chloride removal in chloride-contaminated concrete by applying an external current. Numerical examples are presented and results are validated using published experimental data.