Early residual splitting tensile strength of concrete at elevated temperature

Assessment of the fire-induced spalling of high strength concrete in concrete structures requires knowledge of the tensile strength of concrete at an elevated temperature. However, previous research is mainly focused on determining residual tensile strength, measured at the post-fire stage after cooling the specimens to ambient temperature. However, such residual tensile strength is only applicable to concrete after fire exposure and not during the fire event, which is usually more critical. In this study, the early residual splitting tensile strength of concrete at high temperature is determined experimentally. The test results indicate that early residual splitting tensile strength decreases with temperature. To understand this phenomenon, temperature distribution is examined. Compared to residual tensile strength, loss of early residual splitting tensile strength is found to be faster due to the elevated temperature effect. Lastly, in order to reproduce early residual splitting tensile strength, a numerical model is developed and empirical expressions are proposed for engineering application.