New concrete to reduce CO2 emissions
Dübendorf ZH - Die Eidgenössische Materialprüfungs- und Forschungsanstalt (Empa) will in der Bauindustrie verwendeten Beton mit Pflanzenkohle anreichern. Mit dieser Technologie soll die CO2-Bilanz der Schweiz verbessert werden.
Researchers at the Concrete & Asphalt Laboratory of the Swiss Federal Laboratories for Materials Science and Technology(Empa) are developing a concrete that binds carbon. According to a press release, the institute wants to use this research to contribute to the reduction of CO2 emissions for a climate-neutral Switzerland by 2050. In the project, the researchers led by project manager Prof. Dr Pietro Lura note that 8 per cent of greenhouse gas emissions worldwide are caused by cement production. To counteract this, the Empa research team wants to use biochar in concrete production. The carbon found in plants is formed by the absorption of carbon dioxide from the air. No new CO2 is released during the carbonisation process. However, biochar cannot be added directly to concrete.
“Biochar is very porous and therefore not only absorbs a lot of water, but also expensive additives that are used in concrete production,” Empa researcher Mateusz Wyrzykowski is quoted as saying in the press release. The solution proposed by the Empa team is to pelletise the coal components. The coal is mixed with water and cement in a rotary mixer. This produces pellets with a diameter of between 4 and 32 millimetres. These pellets can be used to produce normal concrete of strength classes C20/25 to C30/37 – the classes that are most widely used in building construction and civil engineering today.
“With a proportion of 20 per cent by volume of carbon pellets in the concrete, we achieve net zero emissions,” says Mateusz Wyrzykowski. “This means that the amount of carbon stored offsets all emissions generated during the production of the pellets and the concrete.”
The project is part of the broad Mining the Atmosphere concept being pursued by several research departments at Empa, including the production of synthetic methane gas using solar energy, water and CO2 from the atmosphere in sunny regions of the world and the subsequent pyrolysis of the gas. “This produces hydrogen, which can be used as an energy source in industry or mobility, and solid carbon, which we can process into pellets – like biochar – and incorporate into concrete,” explains Head of Research Lura.