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Building a cleaner world: CO2 based cement and concrete

Since its invention some 150 years ago, concrete has become the most used construction material in the world. Unfortunately, the production of one of the ingredients of concrete, cement, produces about one tonne of carbon dioxide per tonne cement. In total, cement is responsible for about five per cent of CO2 emission in the world. Another major contributor to global warming is the emissions of power plants. This is why several teams of scientists are trying to reduce both of those factors by making concrete and cement out of carbon dioxide emissions.

Capturing CO2 is not new, but usually, it is stored without doing anything with it. Last week, we talked about shoes made from carbon emissions, and now it is time for building materials.

Back in 2008, several companies such as Calera started making cement from CO2 emissions, by turning CO2 into carbonic acid and then making carbonate. The heat of the flue gas is used to employ heat sprayers to dry the slurry that results from mixing the water and pollution, turning in a white cement-like substance, which can either be used on its own or in combination with ordinary cement.

Earlier this year, a team of researchers at the University of California, Los Angeles discovered a way to turn CO2 into a building material in its own right, which they – fittingly – called CO2NCRETE. Combined with lime, they have managed to 3-D print small cones. The biggest challenge they face is to make the building material on a larger scale.

This month, German scientists from the Technical University Dresden were nominated for the Deutscher Zukunftspreis 2016 (German Future Prize) for their project C3 – Carbon Concrete Composite. This material is a corrosion-resistant and resource-conserving alternative to the conventional reinforced concrete. It is made with special concrete and carbon fibres. Around fifty thousand fibres, significantly thinner than a human hair, are woven into a yarn and processed into a coated grid structure. Carbon, compared to steel, is four times lighter and has six times the bearing capacity, so the construction material can be thinner, decreasing the amount of raw materials used, as well as costs in production, transport, and installation.

It would seem that there is a bright future for construction materials made with carbon dioxide. This is good news for the environment, of course – so let’s keep building a cleaner world.

Photos: UCLA

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