Montreal company Carbicrete has developed a method for sequestering carbon in concrete, claiming its product captures more carbon than it emits.

The technology cuts out the need for calcium-based cement, a key ingredient in traditional concrete that is responsible for around eight per cent of all global CO2 emissions.

“It’s negative emissions,” Carbicrete CEO Chris Stern told Dezeen. “We’re taking CO2 out of the system every time we make a block.”

Concrete locks carbon away “forever”

The company is one of many that is racing to find low-carbon or carbon-free alternatives to traditional concrete but is one of the only ones claiming to have achieved negative carbon.

Instead of cement, Carbicrete’s system combines waste slag from the steel industry plus carbon captured from industrial plants that would otherwise have gone into the atmosphere.

“We’re taking it from there and then injecting it into concrete and getting rid of it forever,” Stern said.

More carbon is captured during the production process than is emitted during the manufacture of the concrete, making the resulting concrete carbon-negative according to Stern.

However, the process relies on emissions produced by other industries, so it is helping to reduce the amount of additional CO2 going into the atmosphere rather than actively removing it from the atmosphere.

But as CO2 captured from the sky via direct air capture (DAC) companies such as Climeworks becomes more affordable, concrete could start to play a part in lowering concentrations of atmospheric carbon.

“We’d love to get it from a direct air capture unit,” Stern said. “We’re not there yet just because the industry is not there yet but it’s certainly well-positioned for us.”

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