Effects of microbial repairing and organism attachment on durability of marine concrete

Marine concrete faces durability challenges from the corrosive environment and tidal loads. Microbially induced calcium carbonate precipitation (MICP) technology has the potential to heal concrete cracks, and sessile organism attachment has the potential to delay concrete degradation through providing bio-protection at the concrete surface. This paper presents laboratory-controlled and field exposure tests to evaluate the effects of MICP and sessile organism attachment on the durability of marine concrete. Laboratory-controlled test results show that MICP reduced chloride migration coefficient, electric flux, and carbonation depth of concrete by up to 45%, 17%, and 24%, respectively, and increased 28-day compressive strength by up to 19%. Field exposure test results were consistent with the beneficial effects of MICP on the chloride migration coefficient, electric flux, carbonation depth, and water absorption coefficient of concrete. Field exposure tests demonstrated that the bio-adhesive (thickness ~ 15 μm) secreted by sessile organisms filled pores on concrete surface and mitigated chloride migration. These results indicate that MICP and marine sessile organism attachment have the potential to improve durability of concrete in tidal zones.