Effect of nano SiO2 on rheology, nucleation seeding, hydration mechanism, mechanical properties and microstructure amelioration of ultra-high-performance concrete

Abstract

The use of Nano SiO2 products will likely change cement, concrete construction sector. Their stability, low toxicity, and ability to functionalise with chemicals and polymers have drawn interest. When mixed with hybrid nanomaterials, nanostructured silica with unique geometric properties can improve biomaterial conjugates. Few scientists have studied the effects of Nano SiO2 on cement-based composites microstructural characterisation and mechanical behaviour. In this study four combinations were made by adding 0%, 1%, 2%, and 3% Nano SiO2 by cement weight. The tested Ultra-High-Performance Concrete (UHPC) mixes with various mechanical and microstructural characterisation techniques utilised. The finding suggests that the UHPC mixture with 2% Nano SiO2 has better mechanical and microstructural capabilities than the others. The study found that UHPC samples with more Nano SiO2 had higher mechanical strength than the reference sample. The study found that adding UHPC 2% Nano SiO2 to the mix increased compressive, split tensile, and flexural strength by 56%, 37%, and 28%, respectively. In UPV testing, this UHPC NS-2% mix had the greatest average velocity 4883 m/s and 4951 m/s for 28 and 90 days, suggesting a stronger concrete matrix. In optimum UHPC mix due to nucleation effect of Nano SiO2 and hydration of cement generates to more Calcium Silicate hydrate gel formation and less ca/si ratio is 0.54. It will lead to produce the dense UHPC with lowest porosity. The environmental and economic benefits of UHPC with Nano SiO2 make it a suitable building material for various civil engineering applications.