Abstract
Fire safety is essential in construction, as accidental fires subject concrete structures to high temperatures that result in significant damage. This study examines the development of self-compacting concrete (SCC) characteristics with barite heavyweight aggregate (20-100% substitution of natural coarse aggregate) after being exposed to 600 °C, followed by several post-fire re-curing methods (water, CO(2), water-glass, and air). The property evolution was examined for cracking, density loss, residual compressive strength, and ultrasonic behavior, verified by FTIR, MIP, and SEM-EDX tests. The exposure to 600 °C resulted in widespread microcracking, significant mass loss, and decreased strength, besides the severity increasing with higher barite concentrations due to the brittleness and thermal sensitivity of heavyweight aggregate. Post-fire curing demonstrated specific recovery mechanisms: water curing promoted rehydration and achieved partial strength recovery of approximately 75% of pre-fire values; CO(2) curing improved densification via carbonation but resulted in increased brittleness; water-glass curing partially filled cracks but decreased long-term stability; and air curing caused additional drying shrinkage and further deterioration. The results highlight the interrelated chemical and microstructural changes that influence the post-fire development of SCC characteristics, revealing that water and CO(2) re-curing are the most effective methods for performance restoration.