Mechanical properties of nano-SiO2 modified ultra-high-performance concrete

This study experimentally investigates the effects of varying nano-silica (nano-SiO 2 ) contents on the mechanical properties of ultra-high-performance concrete (UHPC) hardened paste, focusing on compressive and flexural strength improvements. Nano-SiO 2 , owing to its high surface area and reactivity, has potential to enhance UHPC performance by filling micro-pores and promoting cement hydration. In this research, UHPC hardened paste specimens were prepared with nano-SiO 2 dosages of 0 %, 0.5 %, 1 %, 1.5 %, and 2 % by mass of cement, and their mechanical properties were evaluated and statistical features were analyzed. The results indicate that incorporating nano-SiO 2 enhances both compressive and flexural strength of UHPC, with the optimal improvement observed at a 1 % dosage. Specifically, UHPC with 1 % nano-SiO 2 exhibited a 5.1 % increase in compressive strength and a 6.3 % increase in flexural strength compared to control specimens. These findings suggest that a moderate addition of nano-SiO 2 can effectively optimize UHPC’s mechanical performance, offering a promising approach for high-strength, durable concrete in demanding structural applications.