Chloride Binding in Building Materials

Abstract

Salt binding in porous materials is commonly described by ion binding isotherms which express the equilibrium relation between the amount of free ions in the solution and the amount of bound ions on the pore walls in the porous medium. In this article, chloride binding isotherms of several different types of building materials, among them cement paste, ceramic brick, mineral wool, and calcium silicate, are determined using the adsorption method. The experiments are performed on small but not crushed specimens so that the effect of the porous structure is maintained. Also, the experiment with crushed samples as in the original adsorption procedure is done for the sake of comparison, and the differences are analyzed. It is concluded that the chloride binding capacity of building materials may depend on the size of the sample.