Influence of pH on the chloride binding capacity of Limestone Calcined Clay Cements (LC3)

The high solution to solid ratio normally used for the measurement of chloride binding isotherms, leads to a leaching of ions and a decrease of pH. To make binding test more representative of on-site conditions, we investigated the influence of the increase of pH to compensate the leaching. The binding was characterized on plain cement and Limestone Calcined Clay Cements (LC3). The increase of pH leads to a decrease of the amount of bound chloride. This lower binding can be first explained by the lower chloride content in the solid solution of Friedel's salt and hemicarboaluminate hydrate. Moreover, a lower chloride ions adsorption on C-A-S-H is quantified.