Effect of nanosilica on durability and mechanical properties of high-strength concrete

The effect of amorphous nanosilica particles on the mechanical properties and durability of two high-strength concrete (HSC) mixes was investigated. Nanosilica in powder form was used as a partial replacement of cement at dosages of 1 wt% and 2 wt%, and significant improvements in performance were observed for 2 wt% replacement of cement by nanosilica. Micromechanical studies were performed on the nano-modified HSCs to determine the impact of nanosilica on pozzolanic reactivity. Durability assessments such as the rapid chloride penetration test, water sorptivity test and water absorption test revealed significant resistance to chloride penetration, sorptivity and water absorption. These improvements can be mainly attributed to the larger specific surface area of nanosilica, which effectively stimulates both pozzolanic reactivity and the filler effect over the cementitious matrix.