Effect of carbon fiber on mechanical properties of reactive powder concrete exposed to elevated temperatures

An ultra-high-performance cement-based composite like reactive powder concrete (RPC) achieves its exceptional engineering properties due to a dense and homogenous microstructure. To improve the ductility and fire-resistance, RPC is of ten reinforced with a high volume of steel fibers (SF). Due to the issues of high density, low durability, and high conductivity; there is a need to study RPC with lightweight and durable fibers. In this research, the mechanical properties of RPC are studied with a single and hybrid fiber mixture of carbon fiber (CF) and conventional SF. The mechanical properties of plain and fiber-reinforced RPC were examined after exposure to 200 degrees C, 400 degrees C, 600 degrees C, and 800 degrees C temperatures for the 2 h. The results showed that CFRPC mechanically performs up to 85-90% potential of conventional SFRPC. Hybridization of 1.5% SF and 0.5% CF produced synergistic effects on the mechanical properties of RPC at both normal and elevated temperatures. After exposure to 800 degrees C, CFRPC showed about 2, 4, and 5 times higher residual compressive, tensile, and flexural strength an plain RPC, respectively. Compressive strength-per-unit weight of CFRPC was notably higher than SFRPC.