The requirements for autonomic microbiologically-induced calcite-precipitation in concrete

This paper addresses the complex problem of using microbiologically-induced calcite-precipitation as a means of autonomic self-healing of concrete and describes the requirements for the encapsulated bacteria, precursors and nutrients. The paper discusses the need to use copious spore-forming alkaliphilic bacteria that germinate relatively quickly and considers the kinetics of microbiologically-induced calcite-precipitation. Issues relating to pH and temperature are also discussed. The paper also considers the compatibility of the nutrients and organic precursors with concrete. It is concluded that whilst the encapsulation of bacteria, nutrients and organic precursors that lead to microbiologically-induced calcite-precipitation is readily achievable, optimisation of the process requires further biological and engineering research. Some key areas of further fundamental research are highlighted.