Scientists have used bacteria to create a sustainable building material that is alive and can help reduce the environmental impact of the construction industry.
Wil Srubar from the University of Colorado Boulder and his colleagues haveCyanobacteriaof the genus Synechococcus is used to produce building blocks in various shapes. The team combined the bacteria with gelatin, sand and nutrients in a liquid mixture and then placed it in a mold. When exposed to heat and sunlight, the bacteria produced calcium carbonate crystals around the sand particles, similar to how seashells form in the ocean.
As it cooled, the gelatin solidified the mixture into a gel form. The team then dehydrated the gel to harden it, the entire process taking several hours.
The team compares their living material to concrete, a mixture of gravel, sand and cement combined with water. But its mechanical properties are more similar to mortar, a weaker material usually made of cement and sand that is found between the bricks of buildings, Srubar says. It is not yet as strong as normal bricks.
One advantage of using bacteria to make the concrete is that they will continue to grow if they are not completely dehydrated. A stone can be split to make two stones with some additional sand and nutrient solution. The team showed that a brick can produce up to eight bricks in total after several divisions.
The process has the potential to make energy-intensive concrete production more environmentally friendly due to its dependence on photosynthesis. “Concrete is the second most consumed material on earth after water,” says Srubar.
The work was funded by the U.S. Defense Advanced Research Projects Agency (DARPA), and Srubar says the team is currently in discussions with the U.S. Department of Defense to increase production of the concrete and guide its use in construction.
However, the researchers said cyanobacteria require moist conditions to survive - something that is not possible in drier regions of the world. They are working to engineer microbes that are more resistant to desiccation so that they remain alive and functional.
You can find out more about the new building material in theMatter magazineread.
