Application and performance of bacteria-based self-healing concrete

The effect of water-borne contaminants on the durability of structural concrete is well-known and cracked concrete is more susceptible to permeation of these contaminants. Consequently, research has been carried out to develop concrete that can self-heal these cracks reducing the degree of ingress of these harmful contaminants. The use of bacteria-based self-healing concrete has shown considerable potential in laboratory experiments. The research described in this paper was carried out to demonstrate the application and performance of bacteria-based self-healing concrete at a larger-scale. A wall panel containing bacteria-based self-healing concrete was cast at a live construction site and deliberately cracked. It was demonstrated that it was perfectly possible to cast bacteria-based self-healing concrete on site using standard concrete practice and that there was no effect on setting or hardening, that formwork could be stripped as usual, and that surface finish was unaffected. Whilst no clear evidence of healing could be attributed to bacteria-based effects the trial has raised issues that need further consideration, including: temperature conditions, optimum content and distribution of spores and growth media, and scale-up issues.