Can we develop climate-friendly building materials with the help of bacteria and fungi?

In construction, we use cement for everything from foundations to mortar. In fact, the production of cement accounts for five to eight percent of global CO2 emissions.

The production requires a large consumption of energy and natural resources such as lime. All in all, it is a major climate and environmental burden to produce cement.

»We need alternatives. One of them is to be inspired by nature and use living building materials. Through biomineralisation, bacteria and fungi can form rock-like structures, in the same way that seashells and corals form their shells in the ocean. The process requires far less energy than traditional building materials and can also bind CO₂ in solid minerals,« says Mehdi Mehrali, Senior Researcher at the Technical University of Denmark (DTU).

He is leading a research project that, with support from Independent Research Fund Denmark, will try to find climate-friendly alternatives to cement and other common building materials.

In addition, the project will also focus on developing materials that can maintain comfortable room temperatures with minimal energy consumption. This means that the materials absorb heat when the temperature in a room is high, and release it again when the temperature drops, thereby reducing temperature fluctuations and lowering heating and cooling energy demand.

Nature's building materials must live up to today's demands

Mehdi Mehrali has already succeeded in creating sufficiently strong building materials by cultivating bacteria in biowaste, for example waste from the food industry.

Among the other challenges that the four-year project will now try to find solutions to is to be able to produce sufficient building material with high strength. The process also produces ammonia as a by-product, which is not environmentally friendly, the researchers will also try to find solutions to this.

Finally, the materials must also be able to withstand being used for 3D printing.
If the scientists also succeed in developing materials that can regulate the room temperature, calculations show that it can reduce a building's energy consumption by up to 10 percent.

»We hope that with the help of biowaste, we can find cement-free living building materials that have the mechanical properties that are at least close to the standards we want to have in construction. At the same time, we want to reduce the environmental impact,« Mehdi Mehrali said.

Society will benefit from climate-friendly materials

In addition to Mehdi Mehrali, the project group consists of his research colleagues at DTU Tenure Track Researcher Masoud Hasany, who is looking at the properties of materials in 3D printing, Postdoc Peng Jin, who works with developing living building materials, Professor Ahmad Arabkoohsar, who works with thermal energy, and Senior Researcher Arnaud Dechesne from DTU Bioengineering, who works with environmental microbiology and microbial processes.

In addition, the project group collaborates with Dr. Marie-Eve Aubin-Tam, specializing in biophysics at the Technische Universiteit Delft in the Netherlands. 

At the end of the project, the researchers will compare the environmental impact between producing materials with the help of bacteria and fungi and conventional building materials.

»From a societal perspective, research must first and foremost affect CO2 emissions and ensure that we achieve a more climate-friendly environment. At the same time, we want to reuse the waste materials by bringing them into the cycle and also later ensure that the building materials become more recyclable and environmentally friendly,« Mehdi Mehrali concludes.