Chloride resistance and binding capacity of cementitious materials containing high volumes of fly ash and slag

Abstract

A systematic study on the chloride penetration resistance and binding capacity of cementitious materials containing varying proportions of low-calcium fly ash or blast-furnace slag is presented. The results show that a larger water/binder ratio of cementitious materials can enhance its binding capacity but reduce chloride resistance regardless of binder type. At a given water/binder ratio, the chloride-binding capacity of cementitious binder plays an important role in its chloride resistance in the saturated condition. Fly ash can improve the chloride resistance and binding capacity of cementitious binders with the gradual increase of fly ash replacement ratio up to 70%. However, slag-blended cementitious binder shows the highest chloride resistance and binding capacity when the slag replacement ratio is about 40%. A higher volume of slag can result in a decline of chloride resistance and binding capacity. In addition, the Freundlich isotherm provides the best fit for describing the chloride-binding capacity of cementitious materials, regardless of water/binder ratio and binder type.