Abstract
The performance of concrete deteriorates when exposed to fire, but may be recovered by re-curing the concrete in water. A repair method for fire-damaged concrete which utilizes re-curing could reduce waste generation and resource consumption by restoring the performance of the damaged material. However, the capability and mechanisms for such a repair method are not clear. Experiments were conducted to resolve the recovery mechanism under by examining both the physical and chemical perspectives. It was found that durability characteristics could be fully recovered but strength could only recover to 80％ of pre-fire levels. Mechanical deterioration was due to the occurrence of surface cracks and the coarsening of the pore structure, which were caused by thermal decomposition, and recovery was due to pore structure growth and crack self-healing. The growth observed in the pore structure could be attributed to the re-hydration and increase of hydration products which were dehydrated during heating. However, the re-hydrated pore structure is believed to be weaker than the original structure, thus resulting in lower strength even after re-curing.
