As we saw earlier, Hempcrete is amazing stuff. The concrete alternative is sustainable, lightweight, fireproof, acts as a natural insulator, and sequesters CO2.
Hempcrete's properties are passive; the material is not alive. But Wil Srubar, an assistant professor in the Department of Civil, Environmental and Architectural Engineering at Colorado University Boulder, has been wondering: If we used building materials that are still alive, could we yield additional benefits from them?
Wil Srubar and CU Boulder graduate student Sarah Williams in the lab. (Image credit: CU Boulder College of Engineering and Applied Science)
So far, Srubar and his research team's answer is "Yes." Their most recent project, published this month in scientific journal Matter, uses bacteria from the ocean to essentially grow bricks. Fortuitously for the environment, the bacteria does this by absorbing CO2 from the environment, rather than producing CO2, as happens in standard concrete production.
A mold for shaping bricks made out of living materials. (Image credit: CU Boulder College of Engineering and Applied Science)
Using these bricks yields not only an environmental benefit, but also a potential a boon to manufacturers. "We know that bacteria grow at an exponential rate," Srubar told CU Boulder Today. "That's different than how we, say, 3D-print a block or cast a brick. If we can grow our materials biologically, then we can manufacture at an exponential scale."
The possibilities are big. Srubar imagines a future in which suppliers could mail out sacks filled with the desiccated ingredients for making living building materials. Just add water, and people on site could begin to grow and shape their own microbial homes.
A bacteria-grown truss. (Image credit: CU Boulder College of Engineering and Applied Science)
Not all of the bacteria dies in the process of growing into a brick; the team's research showed that the bacteria survived and spawned three generations of itself after 30 days, with its overall population reduced to about 9-14% of the original. And that plucky percentage of survivors yielded a surprising benefit:
The researchers also discovered that they could make their materials reproduce. Chop one of these bricks in half, and each of half is capable of growing into a new brick.
If only the dilapidated front stoop on our farmhouse (pictured below) was made from these bricks. As it stands, I'm going to have to learn some basic masonry skills. With any luck, in the future this will be obviated by bacterial workers.