BACKSCATTERED ELECTRON IMAGING OF CEMENT PASTES CURED AT ELEVATED-TEMPERATURES

The microstructure of cement pastes containing 5% silica fume or 30% ground granulated blast furnace slag was investigated in comparison with plain portland cement pastes. The pastes were cured at constant temperatures of 23 degrees C and 70 degrees C to degrees of hydration of 30 and 70% as indicated by the nonevaporable water content. Backscattered electron images indicate that in general, elevated temperature curing results in a coarser, more continuous pore structure. Both silica fume and slag are effective in reducing the size and continuity of the pores. These results are consistent with measurements of the rate of diffusion of chloride ions through comparable concretes subjected to the same curing conditions.