Bacterial Concrete, a Self-Repairing and Self-Healing Material

Every complex organism goes through some sort of development in terms of size and abilities. It will also, up to a certain degree, be able to heal its wound or damage. Some species, such as reptiles or crabs, will be able to develop new limbs if maimed. Let’s imagine for a moment that static structures like our buildings could benefit from some of those self-repairing abilities. At the University of Colorado in USA they believe that such approach would be viable. And not only that: they have proved it by developing an innovative concrete. Their self-repairing construction materialmakes use of bacteria that metabolize nutrients and water, producing the new material.

More specifically, the team of researches has resorted to a photosynthetic cyanobacterial species from the Synechococcus genus. This bacteria is able to produce calcium carbonate through its metabolic processes, the same compound that allows other creatures such as mollusks to build their portable shell homes. Wil Strubar, the materials scientist heading the technology project explains that the team decided to mix a bacterial culture with sand and hydrogel. The purpose of the latter is to retain water and nutrients which would provide a welcoming environment for bacteria.  Once dried, the material proved to be as hard as cement. The story, however interesting, does not end there.

Strubar and his team splitted the original brick in two and added more sand, hydrogel and nutrients. Six hours later, the cyanobacteria had done its job and now there were two full size bricks. Three generations after, they had eight bricks. These self-healing properties are not only opening the door to the creation of self-replicating materials, but also capable of self-healing when suffering damage, just like the lizard’s tail or the crab’s claw.

The applications of this new concrete are of great interest in the field of construction materials, but not only on our planet’s soil. The lead scientist believes that this bacterial construction technique could be useful to build future homes in Mars. Space travelers could then carry bacterial cultures on their missions and harness local construction ingredients to create solid structures and living spaces.

What are ELMs?

ELMs (Engineered Living Materials) are a field of research that is garnering a growing interest among engineers and scientists. While the new construction material developed by the scientists at the University of Colorado is probably one of the most ambitious ELMs created so far in terms of durability and potential, researchers have been working for a long time on similarly based materials.

Some of them have been designed to be used as pressure sensors, while others leverage the photosensitivity of bacteria to create light sensors. At the  Berkeley Lab, for instance, they have developed a bacterial “scaffolding” system that can assemble nanostructures as mollusks do with their shells. The particles attach to the cell surface keeping a regular distance, which enables the creation of predictable and ordered structures. In this case, they made use of the Caulobacter crescentus, a bacteria known for its ability to survive in environments with low nutrients and oxygen.   

Source: Science Mag