Concrete is the material of present as well as future Due to the rapid population explosion and the technology boom to cater to these needs, there is an urgent need to improve the strength and durability of concrete to produce concrete with improved properties, the mechanism of cement hydration has to be studied properly and better substitutes to be added, nano-technology looks to be a promising approach in improving the properties of concrete. nano materials are very effective in changing the properties of concrete at the ultrafine level by the virtue of their very small nano size by filling up the minute voids and pores in the microstructure, Nano-silica mixed cement can generate nano-crystals of C-S-H gel after hydration. These Nano-crystals accommodate in the micro pores of the cement concrete, hence improving the permeability and strength of concrete