Thermal Properties of Hybrid Fiber-Reinforced Reactive Powder Concrete at High Temperature

In order to study the thermal properties of reactive powder concrete (RPC) at high temperatures, the thermal conductivity, thermal diffusivity, specific heat capacity, and linear expansion coefficient of hybrid fiber-reinforced RPC at 20 degrees C-900 degrees C are measured. The formulas of thermal parameters with the volume fraction of polypropylene fiber and the elevated temperatures are fitted and compared with the ordinary concrete (OC) and high-strength concrete (HSC). The results indicate that as the temperature increases, the thermal conductivity and thermal diffusivity first descend and then rise, while the linear expansion coefficient and specific heat capacity first increase and then decrease. The thermal conductivity and specific heat capacity of RPC are lower than that of OC and HSC, and the thermal diffusivity coefficient of RPC is lower than that of HSC and higher than that of OC. Through inputting the measured thermal parameters to the finite-element software, the simulated temperature-time curves of hybrid fiber-reinforced RPC are obtained and compared with the measured curves. It is found that the two curves are basically consistent, and thus the measured thermal parameters are accurate and reliable, and can be used in the numerical simulation analysis of RPC structures under fire.