Mechanical properties of steel fiber concrete modified with nano-TiC and nano-SiO2

The incorporation of admixtures into concrete is a common method to improve its mechanical properties, and this study investigates the effects of nano-SiO2 (NS) and nano-TiC (NT) on steel fiber concrete (SFRC). In this paper, 1%, 2%, and 3% of NS, and 0.5%, 1.0%, and 1.5% of NT were individually mixed into SFRC, and their effects on the compressive, split tensile, and flexural strengths of SFRC at 7 and 28 days were investigated. The effect of mixed NS and NT on the mechanical properties of SFRC was further investigated, as was the ability of modified concrete to resist freeze-thaw damage. The modified SFRC was analyzed using a scanning electron microscope (SEM). The EDS was employed to characterize the elements. The phase composition of the modified concrete was examined using XRD. The distribution of the microporous structure in the concrete was analyzed using the mercury intrusion method. An analysis of variance was conducted using SPSS to examine the interaction between NT and NS. The experimental results showed that single doping with NT and NS had little effect on the 7-day compressive, split tensile, and flexural strengths of SFRC, but improved the 28-day compressive, split tensile, and flexural strengths of SFRC. The mechanical enhancement effect of single blending of NS in SFRC was better than that of single blending of NT, where the optimal addition of NS was 2% and that of NT was 1%. Mixing NS and NT can improve the mechanical strength of SFRC. The optimal dosage is 2% NS and 0.5% NT. Their enhancement rate of compressive strength of SFRC is -8.92%~17.48%, the enhancement rate of splitting tensile strength is -3.85%~13.46%, and the enhancement rate of flexural strength is -6.67%~12.00%. The addition of NT and NS to SFRC can improve concrete's resistance to freeze-thaw erosion. The volcanic ash effect of NS, combined with the filling and nucleation effects of NT carbide, promotes greater consumption of Ca(OH)₂, improving the microstructure of SFRC and increasing its density. NS has a significant impact on mechanical properties throughout the entire SFRC process. Based on the results of the mercury porosimetry test, the internal pore structure of the NS2NT0.5 group was optimized accordingly.