Mechanical properties of reactive powder concrete with different dosage of polypropylene fiber after high temperature

The mechanical properties tests of reactive powder concrete(RPC) with polypropylene fiber(PPF) volume dosage of 0, 0.1%, 0.2% and 0.3% after 20~900°C were performed, including compressive tests of specimens with size of 70.7 mm×70.7 mm×70.7 mm and 70.7 mm×70.7 mm×218 mm, flexural tests of specimens with size of 40mm×40mm×160mm and axial tensile tests of specimens shaped as '8'. The inhibition effect of PPF on spalling of RPC at high temperature was investigated. The effects of PPF content and heating temperature on the mechanical properties(cube residual compressive strength, residual axial compressive strength, residual flexural strength and residual axial tensile strength) of RPC after high temperature were analyzed. The results indicate that the inhibition effect of PPF volume dosage of 0.1% and 0.2% on the spalling of RPC at high temperature is not obvious, while PPF volume dosage of 0.3% can prevent RPC from spalling. The presence of PPF has adverse effect on mechanical properties of RPC at room temperature, but when the temperature is higher than 200°C, the greater dosage of PPF is used, the better the mechanical properties of RPC become. The residual compressive strength, residual flexural strength and residual tensile strength of RPC with PPF increase first and then decrease with the increase of temperature, and the critical temperatures are 300°C, 300°Cand 120°C, respectively. According to the test statistics, equations were established to express the relationships between the residual compressive strength, residual flexural strength and residual axis tensile strength and the heating temperature.