Chloride transport through unsaturated concrete: chloride profile simulations and experimental validation

Abstract

To predict the chloride profile in unsaturated cement-based materials subjected to a saline environment, a mathematical model is proposed and experimental validation is carried out. Chloride transport in partially saturated concrete is coupled with moisture transport in the concrete. The model proposed in this study takes into account the diffusion, the convection by moisture transport (vapour and liquid water), the electrostatic coupling between ions of the pore solution and the chemical interactions considered through linear and non-linear isotherms. First, the simulations show that all these parameters affect the chloride profile mainly in the first 2 cm of the concrete cover. Also, it has been shown particularly that the water sorption isotherm has a great influence on the chloride profile. In fact, the chloride concentration increases with the water/cement ratio for the three sorption/desorption isotherms considered. For the Bradley isotherm, the chloride concentration is weaker than the Guggenheim–Anderson–De Boer (GAB) and Brunauer–Emmet–Teller (BET) isotherms. Second, the model shows a good agreement with the experimental results obtained in two cases: wetting and wick action tests.