Microstructure and properties of expansive cement mortar with silica fume

The effect of adding silica fume to a system of type K expansive cement was studied to characterize the micro-structure, to understand better the influence of the expansive component in mortars with and without silica fume on various physical and mechanical properties. It has heen shown that the expansive component in Portland cement led to coarsening of the porosity of the bulk paste matrix, but caused densening of the microstructure of the transition zone. In the silica fume mortars the influence of the expansive component on the microstructure was not as evident, as the transition zone was dense to start with. These differences in microstructure have been discussed in terms of the physical and mechanical properties of expansive cement mortars with and without silica fume.