Scientists create 'living concrete' that can glow and remove toxins

Handout photo issued by Colorado University Boulder of photosynthetic cyanobacteria growing and mineralising in the sand-hydrogel framework, developed by scientists and referred to as living concrete. Photo: University of Colorado Boulder/PA Wire

Nilima Marshall

January 16 2020 02:30 AM

Scientists have developed what they call 'living concrete' by using sand, gel and bacteria.

Researchers said this building material had structural load-bearing function, was 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 in the US believe their 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, who heads the Living Materials Laboratory at the university 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 their 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.

Marshmallow

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 carbon dioxide from the air and make calcium carbonate, the main ingredient in cement.

"It's a lot like making Rice Krispie treats where you toughen the marshmallow by adding little bits of hard particles," Mr Srubar said.

The team said their hydrogel-sand brick s 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," he said.

The research, published in the journal 'Matter', 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.