Fire-induced degradation of concrete transport properties: a comparative study Available to Purchase

Concrete structures exposed to elevated temperatures during fires undergo significant degradation of their transport properties. Knowledge of this is crucial for assessing structural serviceability and guiding effective repair strategies. Restoring fire-damaged concrete to its original strength, stiffness and durability is essential for long-term performance. The influence of elevated temperatures and subsequent cooling regimes on the transport properties of concrete were investigated in this study. Concrete specimens were subjected to temperatures of 300°C, 500°C and 800°C for durations of 1 h and 2 h, followed by natural cooling and water quenching. After 28 days of water curing, the transport properties of heated samples, including air permeability, water permeability, sorptivity and accelerated chloride migration, were evaluated and compared with those of unheated control samples. Compressive strength was also assessed at elevated temperatures. Microstructural analysis was conducted to investigate the underlying mechanisms of the observed changes. The results showed that elevated temperatures significantly degraded transport properties, with water quenching exacerbating the deterioration compared with natural cooling. Thermal shock thus significantly impacts the long-term durability of fire-damaged concrete structures. Notably, the deterioration of transport properties was more pronounced than the reduction in compressive strength, highlighting the critical importance of considering these properties for effective repair and restoration of fire-damaged concrete.