Studies Turn to Calcium Carbonate as Alternative


Researchers at Montana State University are reportedly working on sustainable alternatives to concrete, focusing on microorganisms.

MSU’s Center for Biofilm Engineering, Assistant Research Professor Erika Espinosa-Ortiz is leading the charge, along with Mechanical Engineering Professor Chelsea Heveran.

“We’re wondering if we can better use microorganisms like bacteria and like fungi to build building materials in a different way that have the potential to be reusable and to be recyclable,” Heveran said in an interview with Montana Public Radio.

The team recently received a half million-dollar grant from the National Science Foundation and is experimenting with an approach that would allow bacteria to grow within the materials, sort of like a fibrous scaffold.

“We have tested these with bacteria, and we are in the process of testing with the fungus,” Espinosa-Ortiz said. “We fill the syringes with sand. We have all sorts of different kinds of sand. This is coarse sand and then fine sand.”

Tubes are attached to either side of the syringes, through which researchers pump in a liquid that includes a fungus. The fungus then spreads into branched networks known as mycelium.

The calcium and bacteria activate a chemical reaction to form calcium carbonate, the main mineral found in seashells and pearls, which is the center of the research.

“Once I break that cement into pieces, I have very, very limited ability to reuse those pieces for anything else, and I can’t grind it back down and just pour it as new cement. The neat thing about calcium carbonate is that we can potentially break that down and use it as new inputs into other building materials,” Heveran said.

For this project, which is estimated to take aobut two years, the team is focusing on creating blocks and that be glued together with a biocement, taken apart and then reassembled.

Other Calcium Carbonate Research

At the beginning of last year, researchers at University of Colorado Boulder published a study in the journal Matter that described an approach to designing more sustainable buildings.

In the publication, engineer Wil Srubar and his team describe the strategy for using bacteria to develop building materials that “live and multiply.” The idea is that the structures would be able to heal their own cracks, absorb toxins from the air or even glow “on command.”

The crux of the research was cyanobacteria. Under the right conditions, the university says, the microbes absorb carbon dioxide and grow to make calcium carbonate.

In terms of manufacturing, the researchers add cyanobacteria into a solution of sand and gelatin. The calcium carbonate mineralizes the gelatin, which binds with the sand and creates a brick. This process also removes carbon dioxide from the air, as opposed to creating it like the manufacturing of standard bricks.

The team’s research included strength tests and found the “living bricks” to have the same strength as regular mortar.

Other Mycelium Projects

In 2017, an international group of architects has presented its experimentation with living fungus as a structural element at the Seoul Biennale. Designed and created by architect Dirk Hebel and engineer Philippe Block, the tree-shaped installation, known as the MycoTree, demonstrated that mycelium can be used in construction, if the material’s limitations are accounted for in design and execution.

And, earlier that year, a student at Brunel University London brought using mushrooms in construction materials back to the surface for the university’s Made in Brunel exhibition.

Aleksi Vesaluoma worked with London-based architectural firm Astudio to create “mushroom sausages”—a construction material that combines mycelium and cardboard—to make up his “Grown Structures” technique.

At the end of 2019, Dutch Design Week featured a new pop-up performance pavilion that was constructed entirely of bio-based materials.

The Growing Pavilion, designed by artist Pascal Leboucq of firm Company New Heroes in collaboration with Eric Klarenbeek’s studio, constructed the pavilion with panels grown from mushroom mycelium supported on a timber frame.

Two types of natural coatings were used in the project, according to the piece’s material atlas:

  • Impershield Coating, from Impershield Europe – This coating is made from resin from tree barks and grasses from Mexico. Growing the grasses takes six months and they can be harvested twice a year, whereas the bark falls off the tree by itself. Once the bark has fallen, the resin is removed. Together with the grasses, it is made into Impershield through fermentation.
  • Xyhlo Coating, from Xyhlo Biofinish – Billed as the first 100% natural wood-coating, it consists entirely of softwood, crude linseed oil, aureobasidium pullans (a self-healing fungus), water, sugars, biological thickener, starch and organic emulsifier.

Tagged categories: Cement; Coatings Technology; concrete; Green building; NA; North America; Research and development; Sustainability

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