The process of making self-healing concrete is a relatively simple one. Microcapsules containing mineral healing agents are incorporated into the concrete mix before it is poured. When a crack is created, the bacteria begin to feed on the calcium lactate present in the concrete, converting it into calcite. This calcite seals the crack and prevents further damage. The next step is the addition of micro-encapsulated sodium silicate, which reacts with calcium in the concrete, forming a calcium-silica-hydrate gel that hardens in about a week.
Another key benefit of this type of concrete is that it contains bacteria and a form of starch. The bacteria stay dormant in the concrete, but are awakened when the air gets inside the structure. The bacteria eat the starch and excrete calcite, a form of calcium carbonate, which bonds to the concrete and fills the crack. Eventually, the entire structure will look as good as new.
Cracks in concrete are caused by excessive tensile force. They may occur soon after a structure is built. In this case, the cracks need to be repaired by injecting concrete mortar into them. These repairs can be very time-consuming and difficult to reach. However, the technology behind this material has advanced to a point where it can self-heal from small cracks to large, extensive ones. The technology enables self-healing concrete to fix these cracks without requiring a large amount of work or expensive materials.