Effect of Post-Fire Curing on the Compressive Properties of Fire-Damaged Ultra-High Toughness Cementitious Composites

Abstract After exposure to fire or high temperatures, the post-fire curing methods have a significant effect on the mechanical properties of concrete material. In present research, the influence of post-fire curing methods on the mechanical properties of fire-damaged ultra-high toughness cementitious composites (UHTCC) was investigated. A heating temperature up to 800°C, lasting for 2 hours, was adopted to simulate the fire damage, after which the heated specimens were subjected to three types of cooling regimes (i.e., cooling in air, quenching in water for 5 minutes, and quenching in water for 30 minutes). The quenched specimens were then cured in air for 1 hour, 1 day, 7 days, and 28 days. It was found that quenching in water helped the recovery of the compressive properties of UHTCC, and the extent of recovery increased with the quenching time as well as the post-exposure curing age. The microstructural characterization of UHTCC was also examined before and after exposure using scanning electron microscopy. The pore size distribution was obtained by the mercury intrusion porosimetry analysis. Results from the microscopic observations well explained the mechanical properties of post-exposure UHTCC specimens.