Damage evolution in pre-damaged high-performance concrete after heating and cooling

Temperature-dependent concrete damage-plasticity concept has been often implemented in structural fire engineering, despite the lack of experimental calibration data. However, when concrete, damaged under service or extreme loads, gets exposed to elevated temperatures it suffers from internal stress-concentration and weakened Interfacial Transition Zones (ITZ), which severely affects its constitutive behaviours. Despite this vulnerability, experimental data observing the constitutive behaviours of pre-damaged concrete at elevated temperatures remain limited. Current experimental study explores the dynamic interactions between prior damage and nature of sustained loading during exposure, both compressive and tensile, on the residual softening behaviour and damage evolution. Displacement-controlled cyclic compression and direct tensile tests reveal that strength attributes alone are insufficient indicators to concrete’s residual performance at elevated temperatures. The experimentally derived evolutions under compression and tension provide crucial insights towards the development of advanced material models, to capture post-fire behaviour of pre-damaged concrete in crushing or cracking failures.