Calcite precipitation by environmental bacteria as a method to improve durability of cementitious materials

The need for greener and more sustainable technologies within the construction industry has become a concern amid growing unrest over environmental issues. Concrete is one of the most widely used construction materials worldwide but also carries significant environmental and economic costs associated with both production and maintenance. Many of these costs are exacerbated by problems with durability of concrete, often caused by the formation of cracks that influence the permeability of these structures and allow ingress of aggressive substances that cause corrosion and eventual structure failure. Microbially-induced calcite precipitation (MICP) is a process whereby the deposition of calcium carbonate can occur as a by-product of microbial metabolism. This has already been used in a diverse range of applications, including soil engineering to improve soil characteristics, bioremediation of contaminated sites, and for crack sealing in self-healing cementitious materials. We here report on our profiling of environmental bacteria and their relevance as a source of strains for use in self-healing applications. Our work has shown that different microbial metabolisms can result in different mechanisms of precipitation, possibly impacting on performance in application. This had led to further investigations of how these differences can be used to our advantage when optimising self-healing applications, with particular emphasis on crack sealing in cementitious mortars.