Chloride Distribution Feature in Surface Layer of Cement Paste under Cyclic Drying-Wetting Condition

Abstract

This research focuses on chloride distribution in the surface layer of cement paste and the relation between chloride distribution and pore structure under two different drying-wetting regimes. The results of chloride profiles obtained by three different methods reveal that it dose exist a feature that chloride content first gose up then down with a maximum value Cmaxappearing in the homogeneous surface layer of cement paste subjected to indoor cyclic dry-wet condition. Besides, the Cmaxincreases with the ratio of water to cement (W/C) increasing. And the regime with higher drying temperature and longer wetting time leads to higher Cmax. Moreover, Cmaxappears at the same location for both total and free chloride. In addition, Cmaxincreases with total porosity, the most probable pore size, and average radius increasing, while it decreases with tortuosity decreasing.