Many of the aspiring civil engineers had come across the concept of self-healing concrete in their career. Many researchers in world are currently working on this concept to optimize the life cycle of the structure. There are various methods to achieve this result, using specialized bacteria is one of widely used one.
Generally, Microcracks are present in concrete and develops its size with time under sustained load. Micro cracks are considered under as serviceability issue, whereas after certain point it affects the strength of the structure. This causes the concrete to deteriorate, harmful substances enter the concrete, and the structure wears out. At this point, the concrete needs to be repaired. Application of self-healing methods to overcome these situation makes structure healthy for long period of time. Biomineralization techniques have shown promising results in sealing micro-cracks in concrete. Addition of urease engendering bacteria along with calcium source results in calcite precipitation in concrete. Freshly poured micro-cracks can be repaired to the concrete through a continuous hydration process.
ureolytic bacteria, including Bacillus Pasteurii and Bacillus Subtilis, which can generate urea after combining with a calcium source to close newly formed microcracks by CaCO3 precipitation. To improve the porous structure of the concrete, the concentration of bacteria was optimized. Literature survey indicates that the encapsulation method will give better results than the direct application method, and it has also been shown that the use of bacteria can improve the strength and durability properties of concrete.