The effects of the types of fibers on mechanical properties of normal and high strength concrete under high temperature, up to 700 °C, was investigated. Three different- type fiber; "Steel Fiber (SF), Glass Fiber (GF) and Polypropylene Fiber (PPF)" are added into the concretes in five different ratios (0, 0.50, 1.00, 1.50 and 2.0%)of the volume under the following temperatures; 22, 100, 400 and 700°C. The results indicate that all the different types of fibers researched contribute to both the compressive and flexural strengths of concrete under high temperature, however, it is also found that this contribution decreases with an increase in temperature. The flexural strengths and compressive strengths for NSC and HSC mixes at 28 days under high temperature decreases as the temperature increases especially up to 400°C. Also, the best compressive and flexural strengths performance under high temperature was also those of SF. The compressive strength of the concrete incorporating SF was reduced under high temperature only, while the mixes containing PPF and GF were reduced under high temperature or with fiber addition. The optimum fiber addition ratios of the mixes containing PPF and GF are between 0.5-1.0 percent by volume. And for SF, it is 1.5% by the volume.
Mechanical properties of high-strength concrete at elevated temperatures
