Chloride transport in partially saturated cementitious material: influence of hydric state and binding chloride

Abstract

This study investigated the influence of saturation state on the ingress of chloride ions into a cementitious material. The chloride concentration profiles were determined experimentally for different degrees of saturation, while ensuring optimal contact between the material and saline solution. The experimental profiles were adjusted to a particular solution of Fick's law of diffusion to obtain the corresponding diffusion coefficient. The results showed that the transfer of chlorides depends on the saturation state. It was found that a decrease in moisture content from 97% to 76% led to higher chloride content in the material. Furthermore, for a hydric state with a relative humidity of 76%, the penetration depth of chloride ions was important while their binding to the cementitious matrix was low. This caused the concentration of free chlorides (harmful chlorides for construction) to be larger in the pore solution, meaning that the material was more vulnerable with regard to corrosion.