Application of ureolysis-based microbial CaCO3 precipitation in self-healing of concrete and inhibition of reinforcement corrosion

Cracking is inevitable in concrete due to its quasi-brittle nature. The presence of micro-cracks will not only impair concrete, but induce reinforcement corrosion by providing paths for the ingress of harmful species. In the past decades, a new technique to repair cracks automatically based on microbial induced carbonate precipitation has become attractive. This paper explored the crack healing potential of reinforced concrete incorporated with ureolytic type microbial self-healing agents immobilized in porous ceramsite particles. Effects of healing on the mechanical and electrochemical performances of reinforced concrete were investigated. The maximum crack width that could be healed completely by bacteria was up to 450 μm in 120 days. The highest regain ratios of flexural strength and modulus were achieved by bio-based healing when the initial damage degree was taken into account. As indicated by the Tafel polarization results, reinforcement corrosion was successfully inhibited by the crack closure from microbial precipitation without any side-effects.