DURABILITY AND HEALING EFFICIENCY OF SELF-HEALING CONCRETE USING BACTERIAL AND MINERAL ADDITIVES IN TROPICAL CLIMATES

Concrete structures in tropical regions often experience reduced durability due to elevated temperatures, strong solar radiation, and frequent heavy rainfall, which accelerate microcrack development and chemical degradation. This research examines the performance of self-healing concrete (SHC) incorporating bacterial and mineral-based healing agents under tropical environmental conditions. Bacillus subtilis spores encapsulated in lightweight aggregates were employed as the bacterial healing agent, while the mineral-based system comprised micro-encapsulated calcium carbonate and silica fume. Three concrete mixtures were produced: conventional concrete (CC), bacterial self-healing concrete (BSHC), and mineral-based self-healing concrete (MSHC). Induced cracks were introduced in the specimens, which were then exposed to simulated tropical weather cycles involving alternating wet–dry and heat–cool conditions over a 90-day period. Healing performance was assessed through measurements of crack closure, reduction in water permeability, and recovery of compressive strength. The results showed that BSHC attained an average crack closure of 82% and a compressive strength recovery of 78%, while MSHC recorded 76% crack closure and 73% strength recovery. In contrast, CC exhibited minimal self-healing capability. Water permeability was reduced by 65% in BSHC and 59% in MSHC, demonstrating a notable enhancement in durability. Overall, the findings highlight the effectiveness of both bacterial and mineral-based healing agents in improving concrete performance in tropical climates, with bacterial-based systems showing marginally better results. The adoption of self-healing concrete in tropical infrastructure is therefore recommended to enhance service life and reduce long-term maintenance requirements.