Abstract: Nano-silicon carbide, silicon carbide whisker and silicon carbide fiber were added into concrete. The effects of three kinds of silicon carbide materials with single addition on the mechanical properties of concrete were studied, and the optimal content of three kinds of silicon carbide materials was determined. The improvement effects of three kinds of silicon carbide materials on the mechanical properties of concrete were compared and analyzed. On this basis, the high temperature test of concrete was carried out, and the effects of three kinds of silicon carbide materials on the high temperature properties of concrete were studied. The effect mechanisms of three kinds of silicon carbide materials on the properties of concrete were analyzed by SEM test. The results show that nano-silicon carbide, silicon carbide whisker and silicon carbide fiber can improve the mechanical properties and high temperature properties of concrete. When the content of nano-silicon carbide, silicon carbide whisker and silicon carbide fiber is 2.0%(mass fraction), 3.0%(mass fraction) and 0.3%(volume fraction), the mechanical properties of concrete are the best. The improvement effect of nano-silicon carbide on compressive strength and residual compressive strength after high temperature of concrete is the best, and the improvement effect of silicon carbide whisker on flexural strength, splitting tensile strength and residual flexural strength after high temperature of concrete is the best. In concrete, nano-silicon carbide plays the role of filling and nano-nucleation, silicon carbide whisker plays the role of filling and cracking resistance, and silicon carbide fiber plays the role of cracking resistance. Silicon carbide materials have good high temperature properties, it remains intact at high temperature and can still play a role.

Key words: concrete, nano-silicon carbide, silicon carbide whisker, silicon carbide fiber, high temperature