Experimental study on dynamic mechanical properties of hybrid fiber reinforced concrete at different temperatures

This paper quantitatively explores the regulatory effects of rice husk ash content, polypropylene fiber, and steel fiber volume fractions on the mechanical properties of hybrid Fiber reinforced concrete (HFRC) through a series of orthogonal design experiments. Using the Split Hopkinson Pressure Bar (SHPB) technique, the dynamic mechanical behavior of HFRC and ordinary concrete (OC) under various temperature gradients was examined, revealing the interactive influence mechanisms of temperature and strain rate on the dynamic mechanical properties of HFRC. The results indicate that the steel fiber content predominantly determines the compressive and tensile strengths of HFRC, while polypropylene fiber plays a crucial role in enhancing the tensile performance of HFRC. Optimal mechanical performance was achieved with 12% rice husk ash content, 0.1% polypropylene fiber volume fraction, and 0.5% steel fiber volume fraction, resulting in a 10.41% and 50.22% increase in compressive and tensile strengths, respectively. Under high-temperature conditions, HFRC exhibited significantly superior mechanical properties compared to OC, particularly in terms of dynamic response characteristics. As the temperature increased, the dynamic compressive strength, dynamic increase factor, and peak toughness of HFRC initially decreased and then increased, consistently maintaining levels higher than those of OC. This research provides a solid scientific basis for enhancing the disaster resistance of concrete structures in fire environments.