TAGRA 2024

Fire is one of the important durability problems that cause negativities in civil engineering structures. Irreversible problems occur in the physical, chemical and mechanical properties of concrete elements when structures are exposed to high temperatures during fire. In recent years, it is known that fiber-reinforced concretes have shown significant improvements in mechanical properties, especially flexural strength and toughness, compared to plain concrete. In addition, the use of fiber is also an important parameter in making concrete fire resistant. In this context, the performance of concrete mixtures prepared using steel and basalt fiber under the effect of high temperatures was investigated in the study. After the mixtures were exposed to temperatures of 400 °C, 600 °C and 800 °C, the mechanical properties of the samples such as ultrasonic pulse velocity (UPV), compressive and flexural strength were examined. In particular, the use of steel fibers caused increases in the compressive and flexural strength of the concrete at ambient temperature. On the contrary, replacing steel fiber with a certain amount of basalt fiber in the mixtures caused a decrease in the mechanical properties before elevated temperatures.The hybrid use of steel fibers with basalt fibers in the mixtures gave better results than the single steel fiber concrete in the relative residual strength values of the samples, especially after 600 °C and 800 °C.