Moisture and ion transport properties in blended pastes and their relation to the refined pore structure

This paper presents a study of the moisture transport properties in blended pastes measured by a new procedure and setup. The dependence of moisture transport coefficient on relative humidity (RH) is confirmed. The differences in the moisture dependency may be due to discrepancies in the critical RH for the percolation of liquid. Fly ash and slag increase the percentage of mesopores or “ink-bottle” pores with a mesoscale neck and they strongly reduce the pore connectivity in pastes. These effects cause the evident reduction in the moisture and chloride diffusivity. The additional replacement with limestone filler has little effect on the pore connectivity. The formation factor controls the moisture transport at the high RH interval, but the volume of small pores (middle capillary and mesopores) is the major determinant at a low RH interval. The relationship between water-binder ratio, pore structure and moisture transport or chloride migration coefficient is discussed.