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Paint made from waste concrete powder sequesters CO2

London and Seoul based designer Kukbong Kim developed a paint called Celour made from waste concrete powder, leftover from recycling concrete, which actively captures and stores CO2.

Concrete is composed of aggregates and cement. Annually, more than 140 tons of concrete are recycled in the US alone. In the recycling process, the two components are separated, and only aggregates are reused, while cement-based concrete powder ends up on the landfill, about 20 to 50% of the total concrete amount recycled. Once in the soil, the waste powder alkalizes the ground and water by mixing with rainwater and groundwater, which causes severe environmental pollution.

While cement does not have the best reputation as an environmentally friendly material, since it is the ingredient in concrete which causes its enormous carbon footprint, surprisingly, the cement ingredients in waste concrete powder is capable to capture and store carbon dioxide by mineral carbonation. This is a coercion in which the CaO (calcium oxide) component inside the powder reacts with CO2 to form CaCO3 (calcium carbonate). Compared to other carbon capture storage methods, mineral carbonation stores CO2 in a stable form for a long time.

From this, Celour paint was developed. With the added waste concrete powder, Kim aims to kill two birds with one stone: move the powder away from landfills where it causes environmental damage, and also sequester CO2 which also causes environmental damage. If 135 g of Celour is fully carbonated, it sequesters 27 g op CO2, the same amount of what a tree absorbs per day.

Photos: Kukbong Kim

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