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Concrete carbon locked away by new technologies



As companies tackle the issue of concrete’s carbon emissions, the storage of carbon within the product has been raised as a useful alternative to meet sustainability targets.

CarbiCrete, a Canadian carbon removal technology company, is developing solutions for the construction industry to lower its carbon dioxide (CO2) emissions with its namesake product.

Where some low carbon concretes use fly ash or blast furnace slag from coal plants to replace clinker in cement, CarbiCrete uses steel slag from steel manaufacturing.

“There’s 250 million tonnes of it made every year,” Carbicrete’s chief executive Chris Stern told Wired.

“For years, steel slag has basically been used for road fill. Some goes into roads, the smaller bits go into landfill, it’s sometimes used in fertiliser, but there’s not a huge usage rate.”

Each concrete masonry unit (CMU) made from CarbiCrete has one kilogram of CO2 permanently embedded in it, while a further 2kg are avoided in its production compared to traditional concrete.

Wired also put the spotlight on another building products supplier from the United States called Solidia.

The company uses less lime and more clay to allow for lower temperature kiln firing and fewer carbon emissions.

Solidia’s concrete curing process uses CO2 instead of water, sequestering the carbon within while using 30 per cent less energy and 30 per cent less emissions.

Solidia chief executive officer Bryan Kalbfleisch told Wired the concrete also reduced water usage.

“Ordinary Portland cement-based concrete products consume around 2.6 trillion litres of water annually,” Kalbfleisch said.

“Our technology enables the customer to recover greater than 90 per cent of the process water.

“Hopefully, that frees up water in countries that are experiencing a water crisis to be used for drinking and agriculture.”

More reading

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Industry sees bottom-up push for sustainability

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