Performance of polypropylene-steel hybrid fiber reinforced concrete after being exposed to high temperature

Through the experiments on the specimens after being heated to certain temperatures, the exterior appearance, thermal spalling, mass loss and mechanical properties of high strength concrete(HSC) and polypropylene fiber-steel fiber reinforced high strength concrete(hybrid fiber/HSC) were studied. The results show that the HSC specimen spalls after being exposed to 600 ℃, while hybrid fiber/HSC specimen does not spall until being exposed to 800 ℃, which results from the action of hybrid fibers. The mass loss of hybrid fiber/HSC increases with the increasing of temperature. The compressive strength and modulus of rupture of HFRC decrease with the increasing of temperature, especially after being heated to the temperature of 400 ℃. For the same exposure temperature of specimens, the hybrid fibers improve the HSC strength. Based on the statistical analysis of the experimental results, the relational expressions of mass loss, compressive strength, and modulus of rupture with temperature were established, respectively.