Assessment of the durability of nanosilica / Fly ash cement pastes exposed

The aim of this work is to study the effect of fly ash (FA) and nanosilica (NS) on the durability of cement pastes under normal and aggressive curing condition. Different mixes were made with various amounts of NS and constant value of FA (10% by weight of cementitious materials). First group of samples were subjected to normal curing and tested after 3, 7, 28 days and after one year, while the second group of samples were subjected to sulphuric acid of concentration 0.2 N and tested after the same ages. The hydration process and durability of cement pastes were monitored using scanning electron microscope (SEM). The results of this study indicated that FA of percentage 10% and nanosilica of percentage 1% of cementitious materials improve the durability and microstructure of cement pastes against both normal and aggressive curing conditions