Evaluating the impact of nano-silica particle size on pozzolanic reaction kinetics, mechanical strength and durability of portland slag cement

Abstract

Theoretically, incorporating Nano-silica (NS) into cement-based composites enhances their mechanical properties and durability in marine environment by virtue of nucleation effect, pozzolanic effect and filling effect. However, an investigation on the precise effect of NS particle sizes on PSC performance is lacking. In this paper, the relationship between NS particle size on the reaction kinetics and the mechanical strength and durability of Portland slag cement (PSC) were delved. The reaction kinetics results demonstrated that NS15 displayed the highest pozzolanic activity, but its practical benefits were limited due to the compromised workability of the PSC-NS15. NS30, with its high pozzolanic activity and low rheological effect, showed the best improvement effect on the mechanical properties and durability of PSC. Significantly, compared to the blank sample, PSC-NS30 exhibited a 13.11 % and 8.24 % increase in compressive strength after 3 and 28 days, respectively. Moreover, a notable reduction of 21.64 % in porosity and 12.34 % in chloride diffusion coefficient was observed in PSC-NS30 at 28 days. These findings provide valuable theoretical insights for the judicious selection of NS in marine engineering applications.