Dynamic Thermal-Mechanical Behavior and Constitutive Model of Ultrahigh-Toughness Cementitious Composites under Real-Time High-Temperature Conditions

Abstract This paper investigated the dynamic compressive properties of ultrahigh-toughness cementitious composites (UHTCCs) under real-time high-temperature conditions. A series of dynamic compression mechanical tests were conducted using a split Hopkinson pressure bar system on UHTCC specimens at five different real-time temperatures (20°C, 200°C, 400°C, 600°C, and 800°C). The dynamic compressive stress–strain curves of UHTCC were obtained, and the coupled effects of temperature and strain rate on the peak strength, peak strain, and energy absorption of UHTCC were analyzed. The results indicated that both the dynamic compressive strength and energy absorption capacity of UHTCC decreased with increasing temperature, while they increased with increasing strain rate. A comparison with the test results of UHTCC after pre-thermal treatment revealed that, except for the specimens at 200°C, the reduction rules in compressive strength and energy absorption for the other specimen groups due to the high temperature in these two cases was similar. This study proposed fitting models for the dynamic compressive strength and energy absorption of UHTCC at high temperatures, and proposed a method for converting post-temperature test results into the real-time high-temperature test results. The modified Zhu-Wang-Tang model was established to construct the dynamic compression constitutive relationship of UHTCC under real-time high-temperature conditions.