The Herman Trend Alert

January 29, 2020

Living Building Materials

Imagine a building material as strong as concrete that contains photosynthetic microbes and can even reproduce. That is just what a team of researchers at the University of Colorado, Boulder, has created.

The Past is Not Equal to the Future

Buildings have been constructed using concrete the same way for literally thousands of years. Since ancient times, humans have mixed materials like sand with different binding substances.

Scientists discover Living Concrete

Now, an interdisciplinary team of researchers has created a new kind of concrete. This innovative material is actually alive and can even reproduce itself. In this creation process, cyanobacteria, a common class of microbes, deposit the minerals in the new material; moreover, the bacteria help to capture energy through photosynthesis. The activity of photosynthesis absorbs carbon dioxide; plus, the method of making ordinary concrete produces large amounts of greenhouse gas.

Bonus Benefits

Not surprisingly, due to the photosynthetic bacteria the material starts out green; as it dries, it turns light brown. Second, due to the biology of the new concrete, it virtually heals its own cracks. Finally, their process is positioned around bacteria: using them to build the concrete and keeping them alive so they make more when needed.

Announced to the world in a peer-reviewed journal

Described recently in the journal Matter, the new concrete is one of the first of a new class of low-carbon, designer construction materials. To create this living building material, the scientists began by putting cyanobacteria in a mixture of warm water, sand and nutrients. The microbes readily absorbed light and began producing calcium carbonate, slowly binding the sand particles together. But the process was too gradual for the project's funder, Darpa, the speculative research arm of the United States Department of Defense. The sponsor wanted the creation to go faster. That push from Darpa made all the difference.

The Secret Ingredient

Having previously worked with gelatin, Dr. Wil Srubar an engineer with the University of Colorado, Boulder knew that when dissolved in water and cooled, the substance forms special bonds between its molecules. Most important, gelatin can be used at moderate temperatures that are easy on the bacteria. Srubar suggested adding gelatin to strengthen the bonds being built by the bacteria; the team bought Knox brand gelatin at a local supermarket and added it into the solution with the bacteria. Then they poured the new mixture into molds and stuck it in a refrigerator; the gelatin provided more structure, making the living concrete grow stronger and faster.

A Building Material for the Space Age

Darpa is particularly interested in the reproductive ability of these LBMs---Living Building Materials for construction in remote and austere environments. Not only might LBMs help in environments harsher than even the driest deserts, but they are ideal to take into space and even to other planets, like Mars.

Find more information in the journal article published in Matter.

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