Tensile properties of hybrid fiber-reinforced strain-hardening cementitious composite exposed to elevated temperature

Abstract

A new kind of hybrid fiber reinforced strain-hardening cementitious composite (HySHCC) containing steel fiber, PVA fiber and calcium carbonate whisker was designed. Its tensile behaviors at room temperature and after elevated temperature exposure were investigated. The results indicate that equivalently substitute PVA fibers by steel fibers degraded the tensile strain-hardening ability of SHCC at room temperature. But the addition of an appropriate amount of calcium carbonate whisker improved the tensile strength, toughness and tensile strain-hardening behavior of HySHCC. It was also noticed that the tensile strain-hardening behavior of HySHCCs was eliminated after high-temperature exposure. The addition of calcium carbonate whisker is conducive to the post-temperature tensile strength and toughness while the addition of steel fiber increased the tensile ductility after high-temperature exposure. Through discussing the microstructures, it was found that the softening, decomposing and melting of PVA fiber were the main reasons accounting for the ductility degradation of the designed HySHCCs. Based on the experimental results, a semi-empirical mathematical model was proposed for predicting the tensile stress-strain behaviors of HySHCC after high-temperature exposure. Through comparison between the test results, it is found that the proposed model can be employed to predict the high-temperature tensile properties of HySHCCs.