Fire Spalling of Concrete

Concrete structures can be compromised by various factors, including fires. However, reinforcement exposure to fire can jeopardize the structural integrity of concrete structures. Such exposure significantly impacts both the load-bearing capacity and serviceability of the structure. Fire spalling, a phenomenon caused by increased temperature or fire, leads to complex microstructural changes in concrete. When concrete is subjected to fire, it undergoes intricate microstructural changes. Above 300 ℃, a significant amount of strength is lost, and structural capabilities are substantially compromised. The severity of fire spalling increases with the application of high strength and self-compacting concrete. Moisture, present in volatile and chemically combined forms, plays a crucial role in concrete spalling. Researchers have recognized that the underlying causative mechanisms of spalling are largely unique to concrete. Non-explosive spalling may occur after heating for 60 min or more, which can be mitigated through additional strengthening in the concrete member. While spalling does not imply structural failure, it does impact the overall fire resistance of the element. Therefore, it is essential to follow appropriate safety measures to enhance the fire performance of concrete structures.