In this chapter an overview will be given of the biotechnological possibilities for repair of concrete with focus on application of limestone-producing bacteria and the different metabolic pathways involved, e.g., via hydrolysis of urea and heterotrophic CO₂ production under alkaline conditions. The first paragraph comprises an overview of previously published reports on this subject. In the two succeeding paragraphs, two specific systems for biotechnological repair of concrete structures will be discussed. The first one covers liquid biobased repair systems for durable repair of cracked and porous concrete surfaces, and the second one addresses biobased mortar systems for repair of larger defects of concrete structures. The cases discussed here indicate that concrete repair applying biotech solutions results in improved material durability that can save money and at the same time lower the environmental impact of civil engineering activities. ... Read more

Self-healing of cracks in concrete can be achieved by application of bacteria which metabolically convert organic compounds under aerobic conditions yielding limestone. Added to the concrete mix as part of a healing agent, bacteria can, via metabolic activity resulting in limestone formation, seal cracks of up to 0.8mm width resulting in waterproofing and increased frost damage resistance of the concrete. Besides increasing the autogenous crack healing capacity of concrete, these bacteria can also be applied to improve bond strength of repair mortar and act as limestone producing agent in liquid concrete repair systems. This paper will review current state-of-the art bacteria-based self-healing concrete technologies investigated and applied by the Delft University research group specifically using bacteria which yield limestone after aerobic metabolic conversion of organic compounds under alkaline conditions. ... Read more