Concrete cracks due to several reasons and through the cracks oxygen, water, chlorides and other aggressive agents can penetrate, decreasing the concrete durability, performance and life span. Even though concrete has autogenic capacity to heal the cracks, the size of the cracks that can undergo autogenous healing depends on the exposure conditions and remains below 0.6 mm. In order to improve this healing capacity Microbial Induced Precipitation (MIP) has been investigated. This method, which involves the precipitation of calcium carbonate (CaCO3) induced by bacteria, was implemented at Delft University of Technology for the development of self-healing concrete for new structures as well as for mortar and liquid-based systems for repair of existing concrete structures. This paper presents an overview of the materials, their properties and the successful applications in the Netherlands and overseas.

Keywords: Concrete, Crack, Durability, Self-healing, Bacteria.