‘Living’ bio-concrete could soon reproduce itself and remove air pollution

16 Jan 2020

Bacteria growing and mineralising in the sand-hydrogel structure. Image: Colorado University Boulder/PA

Researchers have revealed a new bio-concrete that is both more environmentally friendly and capable of healing itself when damaged.

Scientists have developed what they call ‘living concrete’ by using sand, gel and bacteria. Researchers said this building material has a structural load-bearing function, is capable of self-healing and is more environmentally friendly than concrete – which is the second most-consumed material on Earth after water.

The team from the University of Colorado Boulder believes its work paves the way for future building structures that could “heal their own cracks, suck up dangerous toxins from the air or even glow on command”.

Wil Srubar and a lab student wearing purple gloves and safety goggles while holding the biomaterial in a lab.

Wil Srubar (left) who heads the Living Materials Laboratory at the University of Colorado Boulder. Image: Colorado University Boulder

‘It’s a lot like making rice crispy treats’

Wil Srubar, who heads the Living Materials Laboratory at the University of Colorado Boulder and is one of the study authors, said: “We already use biological materials in our buildings, like wood, but those materials are no longer alive.

“We’re asking: why can’t we keep them alive and have that biology do something beneficial, too?”

For its experiments, the team worked with cyanobacteria – green microbes that live in the water and can manufacture their own food. While these bacteria are quite small and usually unicellular, they often grow in colonies large enough to see. The team created a scaffold using sand and hydrogel for the bacteria to grow in.

The hydrogel contains moisture and nutrients that allow the bacteria to reproduce and mineralise, a process similar to the formation of seashells in the ocean. These microbes absorb CO2 from the air and make calcium carbonate, the main ingredient in cement.

Srubar said: “It’s a lot like making rice crispy treats where you toughen the marshmallow by adding little bits of hard particles.”

Small beige square moulds of the biomaterial in a black device in a lab.

Green photosynthetic cyanobacteria growing in the sand-hydrogel framework. Image: Colorado University Boulder

The team said its hydrogel-sand brick is also capable of reproducing, demonstrating self-healing capabilities. Researchers found on splitting a lab-grown brick in half that it grew into two complete bricks with the help of some extra sand, hydrogel and nutrients.

“It really demonstrates the capability of exponential material manufacturing,” Srubar said.

The research is still in its early stages and the team said more work needs to be done to address some of the drawbacks. The team’s cyanobacteria, for example, need humid conditions to survive, so Srubar and his team are working to genetically engineer microbes that are more resistant to drying out so they remain alive and functional.

The research is published in the journal Matter.

– PA Media