Mechanical Performance of Steel-PVA Hybrid Fiber Concrete After Elevated Temperature Exposure

The impact of high temperature on the mechanical performances of hybrid fiber-reinforced concrete is of great significance. Therefore, the experimental study on compressive strength, flexural strength, and flexural toughness of hybrid fiber-reinforced concrete after high temperature can provide reference for the study of fire resistance and post-fire evaluation of hybrid fiber-reinforced concrete. In this paper, the compressive strength, flexural strength, and flexural toughness of normal concrete, steel-PVA hybrid fiber-reinforced concrete P1S8 (PVA volume ratio is 0.1%, steel fiber volume ratio is 0.8%) and P1S14 (PVA volume ratio is 0.1%, steel fiber volume ratio is 1.4%) after high temperature were tested, there were 45 specimens in each group, and the macroscopic phenomena during heating and after cooling were observed. The influence of temperature on the mass loss rate of specimens was studied, and the influence of temperature and total fiber volume ratio on the mechanical properties of concrete was explored. The results demonstrate that the mass loss rate increases with both temperature and fiber content. The incorporation of steel fiber and PVA fiber effectively improves the flexural strength of concrete. Moreover, when the volume contents of steel fiber and PVA fiber after high temperature are 1.4 and 0.1%, they are the optimal volume contents. Additionally, the incorporation of steel fiber and PVA fiber effectively improves the equivalent flexural strength and flexural toughness ratio of concrete. The equivalent flexural strength and flexural toughness ratio of steel-PVA hybrid fiber-reinforced concrete increase with the increase of steel fiber volume fraction.