Abstract In this paper, the performance of nanoscale SiO2 in cement paste has been studied. The compressive strength of hardened cement paste and the formation of Calcium Silicate Hydrate (C-S-H) in presence of nano silica (SiO2) increased. Heat of hydration increased with time with the addition of nanosilica. Core shell nanocomposite of titania and nanosilica acted as a cleaning agent and increased the compressive strength of the cement paste. It is concluded that nano silica accelerated the hydration by increasing the amount of C-S-H phase and also acting as a nucleating agent.