Fire Spalling of Concrete Members

Abstract

Thermal instability “spalling” occurs when concrete is exposed to fire. This phenomenon, which happens early after a fire starts (about twenty minutes), is one of the most detrimental effects causing damage to concrete members. It can trigger an immediate degradation of concrete, exposure of steel reinforcements to high temperatures and then eventually can cause failure of the concrete members during or after a fire by decreasing the residual mechanical properties and durability of the structure. In spite of many experimental and numerical studies, the real mechanism of spalling is still not well established. Hence, more comprehensive studies on simulating the behaviour of concrete members exposed to fire to investigate the real physics involved and the affecting factors on this phenomenon are currently lacking. The current study at University of Melbourne is attempted to fill this gap. The lack of understanding of the origin of fire spalling is mainly due to the erratic nature of this phenomenon and inhomogeneity of the concrete structures. To establish a more clear view of the phenomenon further investigation is needed. This paper reports the latest findings on fire spalling behaviour of concrete members and shows the deficiencies of the current experimental work and knowledge.