ABSTRACT
Siliceous by-products such as condensed silica fume, fly ash, and blast furnace slag in combination with Portland cement produce on hydration a pore structure more discontinuous and impermeable than that of hydrated cement paste. This chapter deals with the microstructure of mortar, focusing on the role of the interface. It examines some of the physical properties that are affected by the interface. Scanning electron microscopy (SEM) shows similar features which occur on or near the surface of a glass slide on the silica sand grain present in mortars. The SEM examination of mortars can show the differences in microstructure of mortars containing various types of pozzolans. The shrinkage of mortars containing silica fume has been measured by several workers and results are somewhat contradictory. The corrosion of steel embedded in mortars is an electrochemical process in which the cement pore water acts as the electrolyte. The chapter concludes with a discussion on the durability of mortars.
