Experimental study on the dynamic compressive performance of SHCC after elevated temperature exposure

This paper investigates the experimental findings on the dynamic compressive performance of SHCC (Strain-Hardening Cementitious Composites) subjected to elevated temperature and different strain rates. SHPB (Split Hopkinson Pressure Bar) tests were performed by considering the influence of strain rate ranges from 40 s -1 to 160 s -1 , at different temperatures of 25 °C, 200 °C, 300 °C, 400 °C, 600 °C and 800 °C. The dynamic compressive behaviour and the full-field dynamic strain distribution of thermal-damaged SHCC under impact loading were analysed. Moreover, the cracking patterns and microstructure were studied using X-ray CT and SEM (Scanning Electron Microscope), respectively. The obtained results show that the dynamic compressive stress and energy absorption capacity of SHCC are significantly increased with the increase of strain rates regardless of thermal-damage, showing a noticeable strain-rate-strengthening effect. For elevated temperature of 800 °C, the dynamic compressive stress and energy absorption capacity are increased by 72.03% and 167.57% for strain rates from 61 s -1 to 85 s -1 , respectively. Moreover, thermal-induced deterioration may result in a distinct decrease of strain-rate-strengthening effect after exposing to elevated temperatures above 400 °C. DIF (Dynamic Increase Factor) models for assessing the strain rate effect are established considering the influence of temperature and strain rate. In addition, multiple microcracks can still be observed for thermal-damaged SHCC after impact loading. The generation of multiple microcracks and fiber pull-out can consume a lot of impact energy, which is the main reason for the dynamic mechanical properties of thermal-damaged SHCC.