An interdisciplinary team at UC Boulder has invented concrete that is alive and can even reproduce! The novel material’s minerals are deposited by cyanobacteria, a bacterium that captures energy via photosynthesis. This is incredibly different from the manufacturing process of standard concrete, which emits significant volumes of CO2. To battle this standard, others have tried to incorporate life into concrete and create concrete that can self-heal. That didn’t go well, though. The new material’s designers claim that instead of adding bacteria to unfriendly concrete, their approach uses bacteria to construct the concrete and maintain them alive to generate more later.
So, how did they do it?
The researchers initially attempted to grow cyanobacteria in warm water with sand and fertilizers. In response to the light, the bacteria produced calcium carbonate, eventually cementing the sand particles. But the procedure was sluggish, and Darpa, the project’s backer, wanted it done immediately. Need spawned invention.
Dr. Srubar, the head researcher, had previously studied gelatin, a food item that generates unusual molecular connections when dissolved in water and chilled. It may also be used at low temperatures, which is suitable for germs. So the crew was fascinated when he recommended adding gelatin to the cyanobacterial matrix. The researchers dissolved Knox brand gelatin in the bacterial solution. When they put the liquid into molds and refrigerated it, the gelatin formed its linkages, much like Jell-O. Then, to help the living concrete develop stronger and quicker, the gelatin added structure.
Voila!
An overnight mix yielded 2-inch cubes, shoebox-sized blocks, and truss parts with struts and cutouts, among other shapes. Despite its weakness, individual two-inch cubes were robust enough for a human to stand on. In addition, shoebox-sized blocks showed promise for serious building.
The blocks attain their full strength in days when stored in reasonably dry air at room temperature, and the bacteria progressively die off. However, the blocks are still alive after a few weeks; high temperatures and humidity revive many bacterial cells.
The group can take one block, cut it using a diamond-tipped saw, put half of it back in a heated beaker with additional raw ingredients, and start again. Each block could therefore produce three generations of three blocks each. The blocks are also manufactured from a range of everyday materials, which isn’t something we can say about standard traditional types of concrete. Most of those need virgin sand from rivers, lakes, and seas, which is limited due to global demand.