Fracture Properties of Plastic-Steel Fiber High-Performance Concrete after High-Temperature Exposure

To study the fracture properties of plastic-steel fiber high-performance concrete at high temperatures, the load-mid-span displacement curve and load-opening displacement curve of plastic-steel fiber concrete were obtained through fracture test conducted before and after exposure to high temperature. By calculating the fracture parameters, fracture energy, and characteristic length of concrete, the relationship of fracture parameters, fracture energy, and characteristic length of concrete with temperature was comparatively analyzed against the experimental results obtained for plain concrete. According to the analytical results, the crack initiation load value, maximum load and crack initiation toughness of SFRC are significantly improved after high-temperature exposure, and the plastic-steel fiber reinforced concrete is effective in reducing the critical value of crack opening displacement for concrete. When the test temperature ranges from 200°C to 600°C, the anti-cracking effect of plastic-steel fiber on concrete is more significant relative to plain concrete. Given temperature rise, the plastic-steel fiber reinforced concrete shows decrease in brittleness but increase in toughness, with the level of fracture energy first increasing and then decreasing. Besides, there is only slight difference observed in characteristic length between plastic-steel fiber reinforced concrete and steel fiber reinforced concrete.