After nine years of research and development, a team from TU Delft presented their self-healing concrete prototype that regenerates itself due to the addition of bacteria in its composition. These bacteria have the ability to “break” some specific components in the concrete and gradually fix small cracks and holes.
Image courtesy of Delft University of Technology
The formula developed at the university goes beyond merely repairing visible imperfections; If not repaired, these cracks can increase in size and allow water to enter the structure, leading to the corrosion of steel and damaging the mechanical properties of the structure.
“We have invented bioconcrete — that’s concrete that heals itself using bacteria,” professor Henk Jonkers from TU Delft told CNN.
The bioconcrete incorporates some species of bacillus bacteria, that can survive up to five decades without food or oxygen. In order to last so long, the bacillus bacteria are stored within the concrete in biodegradable plastic capsules that only break open when they come into contact with water. After being exposed to water, the bacteria feeds on calcium lactate and produce limestone, which closes up the cracks, repairing the material.
“It is combining nature with construction materials,” Jonkers explains. “Nature is supplying us a lot of functionality for free — in this case, limestone-producing bacteria. If we can implement it in materials, we can really benefit from it, so I think it’s a really nice example of tying nature and the built environments together in one new concept.”
The team is currently testing the ability of the bacteria to resist sulfate attacks or extreme temperature variations. In addition, scientists seek to reduce the production cost of the material so that it becomes an affordable alternative in the market, since their commercial potential is very large.