Use of nano-silica to improve the performance of LC3-UHPC: Mechanical behavior and microstructural characteristics.

Ultra-high-performance concrete (UHPC) made of limestone calcined clay cement (LC3) exhibits excellent mechanical properties as well as good environmental friendliness. This paper studied the improving effect of nano-SiO 2 on the mechanical properties and microstructure of LC3-UHPC. The experimental results show that the addition of nano-SiO 2 demonstrates obvious advantages. The mechanical properties of LC3-UHPC are enhanced, and the frictional bond performance between steel fiber and cementitious matrix is also improved. The fiber/matrix bond strength is increased. A constitutive model describing the single fiber pullout behavior is established, and the values of related parameters are suggested. Besides, nano-SiO 2 also refined the cementitious microstructure of UHPC and made the matrix denser. Based on the comprehensive analysis of mechanical properties and microstructural characteristics, the optimal content of LC3 and nano-SiO 2 were proposed. [Display omitted] • The performance of LC3-UHPC was improved by using nano-SiO 2. • The microstructure of UHPC using nano-SiO 2 was optimized. • The fiber/matrix bonding behavior of LC3-UHPC was improved. • Comprehensive evaluation of the influence of nano-SiO 2 was conducted. [ABSTRACT FROM AUTHOR]