Comparison of compressive and splitting tensile strength of high-strength concrete with and without polypropylene fibers heated to high temperatures

This paper presents the results of an extensive experimental study on the compressive and splitting tensile strength of high-strength concrete with and without polypropylene (PP) fibers after heating to 600 °C. Mixtures were prepared with water to cementitious materials ratios of 0.40, 0.35, and 0.30 containing silica fume at 0%, 6%, and 10% cement replacement and polypropylene fibers content of 0, 1, 2, and 3 kg/m³. A severe strength loss was observed for all of the concretes after exposure to 600 °C, particularly the concretes containing silica fume despite their good mechanical properties at room temperature. The range of 300–600 °C was more critical for concrete having higher strength. The relative compressive strengths of concretes containing PP fibers were higher than those of concretes without PP fibers. The splitting tensile strength of concrete was more sensitive to high temperatures than the compressive strength. Furthermore, the presence of PP fibers was more effective for compressive strength than splitting tensile strength above 200 °C. Based on the test results, it can be concluded that the addition of 2 kg/m³ PP fibers can significantly promote the residual mechanical properties of HSC during heating.