Living concrete with self-healing function on cracks attributed to inclusion of microorganisms: Theory, technology and engineering applications—A review

Concrete is the most widely used composite material in civil engineering. Microbial induced calcium carbonate precipitation (MICP) is a green and environmental friendly technology, which has received extensive attention in repair of concrete cracks. This paper introduces the research progress in Southeast University research in past 16 years. In the early stage, MICP technology of urea hydrolyzed by Bacillus pasteurii was mainly investigated to repair the surface cracks and to fill large-size cracks with grouting. However, aiming at the hidden cracks that were difficult for human intervention, a new mineralization route of Bacillus mucilaginosus was proposed, which could repair faster than Bacillus alcalophilus, and the problem of ammonia emission in the repair process of Bacillus pasteurii was also solved. In addition, in order to improve the protection of bacteria and the self-healing efficiency of the later age cracks, the methods of fiber immobilization, carrier uniformly immobilization and core-shell structural immobilization had been compared and studied. The results showed that core-shell structural immobilization had good protection ability and strong designability. What’s more, the paper also summarized the characteristics of spore germination, cell activity, nucleation and biological calcium carbonate in crack zone, and introduced the application experience of microbial self-healing concrete in water conservancy projects and subway stations.