Effect of MICP on reinforcement corrosion of cement concrete exposed to the marine environment

Reinforcement corrosion in marine environments poses a significant threat to the durability of concrete structures. This study investigates the effects of microbial-induced carbonation precipitation on reinforcement corrosion of concrete exposed to the marine environment. The investigation involved a comprehensive evaluation of the mechanical properties, chloride penetration, corrosion performance, self-healing ability, and microstructural analysis of concrete samples treated with microbial-induced carbonate precipitation (MICP) exposed to seawater (SW) and sodium chloride (NaCl) solutions. The study was conducted through compressive, flexural strength, and chloride concentration tests, self-healing cracks analysis, linear polarisation LPR, scanning electron microscopy (SEM), and X-ray diffraction. The experiments used an environmentally friendly, broad-spectrum bacteria, Bacillus subtilis, to perform MICP. The results revealed that Bacillus subtilis through MICP had a negative impact on mechanical strength; after 28d, the compressive strength decreased up to 49.22% and 51.04% for 6% and 2% Bacillus subtilis dosage, respectively. Bacterial concrete had a higher chloride concentration than the concrete without bacteria; an increase of up to 123.28% was observed in 4% bacterial replacement at 84 days of curing. MICP-concrete samples immersed in seawater and sodium chloride solutions showed no healing capability. During the exposure setup for 98 days, LPR decreased over time, indicating an increase in corrosion rate.