The principle of bacteria based self healing concrete is that carbonate precipitating bacteria are added into the concrete during the mixing process. When cracking occurs, the bacteria will be activated to precipitate CaCO3 to in-situ heal concrete cracks.
Bacillus Megaterium bacteria were used in concrete and results shows 24% increase in compressive strength. The deposition of calcium carbonate in concrete by Bacillus Sphaericus improves the durability of concrete.
Therefore, bacterial concrete is a product that will biologically produce limestone to heal cracks that appear on the surface of concrete structures.
These self healing agents can lie dormant with in the concrete for up to 200 years.