Compressive and tensile strengths of reactive powder concrete with hybrid fibres at elevated temperatures

This paper presents the effect of temperature on mechanical properties of reactive powder concrete (RPC) at elevated temperatures. The influences of temperatures, polypropylene (PP) fibre and steel fibre content, hold time, dimension of specimens and explosive spalling were investigated. The microstructure of RPC was identified by scanning electron microscope (SEM). The experimental results show that adding 2% steel fibres and 0.2% PP fibres can prevent explosive spalling and significantly increase compressive and tensile strengths of RPC. PP fibre and steel fibre content played an important role in failures modes, explosive spalling, compressive strength and tensile strength. Cube compressive strength decreases at 100°C, increases between 200 and 500°C, and decreases beyond 600°C. Tensile strength decreases at 200°C, increases from 200 to 300°C, and decreases beyond 300°C. Pores and small channels created are beneficial for mitigating the explosive spalling at elevated temperatures.