Residual properties of high-strength fiber reinforced concrete after exposure to high temperatures

Thermal energy from high temperatures can cause concrete damage, including mechanical and chemical degradation. In view of this, the residual mechanical properties of high-strength fiber reinforced concrete with a design strength of 75 MPa exposed to 400-800oC were investigated in this study. The test results show that the average residual compressive strength of high-strength fiber reinforced concrete after being exposed to 400-800oC was 88%, 69%, and 23% of roomtemperature strength, respectively. In addition, the benefit of steel fibers on the residual compressive strength of concrete was limited, but polypropylene fibers can help to maintain the residual compressive strength and flexural strength of concrete after exposure to 400-600oC. Further, the load-deflection curve of specimen containing steel fibers exposed to 400-800oC had a better fracture toughness.