Chloride binding of alkali-activated slag/fly ash cements

In this study, the effects of slag/fly ash ratio, Na2O concentration, silicate modulus of activators and water/binder ratio on chloride binding of alkali-activated slag/fly ash cements (AACs) are studied, using the binding isotherms. The Langmuir isotherm suits better for chloride adsorption of most of AACs, and the amount of bound chloride is predominantly influenced by the chloride concentration. The Friedel’s salt only presents in alkali-activated slag samples after adsorption equilibrium. An appropriate slag/fly ash ratio could improve the chloride binding capacity due to the physical adsorption of N-A-S-H. The chloride binding of AACs decreases with the increased Na2O concentration but increases with the increased water/binder ratio, which is believed to be related to the OH− concentration in pore solutions