Properties of low binder ultra-high performance cementitious composites: Comparison of nanosilica and microsilica

This paper presents the effect of using binary and ternary blends of nanosilica (NS) and microsilica on the mechanical properties of low binder ultra-high performance cementitious composites (UHPCs). For this, two concrete groups were designed with and without silica fume by weight of cement with a constant water/binder ratio and total binder content. Commercially available NS was used in partial substitution of cement at 0%, 0.5%, 1%, 2% and 3% by weight. The results show that among different NS contents, UHPC containing 2% NS exhibited the best results of compressive strength, splitting tensile strength, modulus of elasticity, flexural strengths, load-displacement behavior and fracture energy at 90 days. The samples of UHPC containing binary cementitious materials (NS and SF) gave better results than concretes containing only NS. Additionally, the effect of 1% NS is almost equal to that 10% of SF.