Evaluation of Mechanical Properties of Concrete after Exposure to Elevated Temperatures Using Ultrasonic Pulse Velocity Measurement and a Split-Hopkinson Pressure Bar

AbstractTo obtain a precise safety evaluation of concrete structures after exposure to the fire hazard, it is critical to comprehend the residual static and dynamic mechanical properties of concrete after exposure to elevated temperature. In this study, the residual mechanical performance of concrete exposed to different elevated temperatures were investigated under the static and dynamic loading, where the compression test, the splitting test, the ultrasonic pulse velocity (UPV), and the Split-Hopkinson pressure bar (SHPB) test were performed, and the deterioration of thermal performance in concrete was interpreted by mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) in detail. Results show that the microstructural change and porosity variation greatly influence the final dynamic mechanical performance subjected to different temperatures. Meanwhile, the effect of strain rate and softening effect due to high temperature also play important roles concerning mechanical performance. Finally, the relationship between the dynamic splitting tensile strength ratio of concrete samples and the temperature is proposed. Meanwhile, the connection between the strain rate and dynamic increase factor under different temperatures was also presented.