Mechanical properties of polyvinyl alcohol-basalt hybrid fiber engineered cementitious composites with impact of elevated temperatures

In the present study, the mechanical properties of polyvinyl alcohol (PVA)-basalt hybrid fiber reinforced engineered cementitious composites (ECC) after exposure to elevated temperatures were experimentally investigated. Five temperatures of 20, 50, 100, 200 and 400 °C were set to evaluate the residual compressive, tensile and flexural behaviors of hybrid and mono fiber ECC. It was shown that partial replacement of PVA fibers with basalt fibers endowed ECC with improved residual compressive toughness, compared to brittle failure of mono fiber ECC heated to 400 °C. The tension tests indicated that the presence of basalt fibers benefited the tensile strength up to 200 °C, and delayed the sharp reduction of strength to 400 °C. Under flexural load, the peak deflections corresponding to flexural strengths of hybrid fiber ECC were found to be less vulnerable ranging from 20 to 100 °C. Further, the scanning electron microscopy (SEM) results uncovered that the rupture of basalt fiber at moderate temperature and its pullout mechanism at high temperature was responsible for the mechanical evolution of hybrid fiber ECC. This work develops a better understanding of elevated temperature and basalt fiber impact on the residual mechanical properties and further provides guideline for tailoring ECC for improved fire resistance.