Moisture transport and sorption in cement based materials containing slag or silica fume

This paper presents the moisture dependency of moisture transport and moisture fixation in mortars with OPC, slag and silica fume. Water vapor desorption isotherms were measured with gravimetric methods and the moisture dependency of moisture transport was investigated with cup-tests. The results show an ongoing evolution of water vapor desorption isotherms from eight months to four years. The evolution is more pronounced for mortars containing slag. The results also show that there is a significant difference in moisture dependency of the moisture transport properties above 70% relative humidity; some mortars exhibit a clear moisture dependency in moisture transport whereas others do not. At a relative humidity below 70%, the water to binder ratio is more decisive for moisture transport than the type of binder. These results are of value for service-life models, where they represent important input data, and for understanding the evolution of the microstructure at later ages.