California-based startup Heirloom Carbon Technologies is using concrete to mineralize carbon in concrete, reports Reuters. Heirloom has partnered with Canadian concrete technology company CarbonCure to deliver c. 30 kg of CO2 collected from the San Francisco Bay area using direct air capture (DAC), the company reported in a press release.

So how does it work? Heirloom placed pre-heated and crushed limestone on large trays, which then absorbed CO2 over the course of three days. According to the company, limestone naturally absorbs CO2 from the atmosphere, and by heating it, the company catalyzed the absorption process. Concrete technology company CarbonCure then mixed the CO2 with concrete ingredients, strengthening the concrete and cutting the need for carbon-intensive cement. CarbonCure also conducted an experiment where it integrated leftover CO2 with water and used it for a new batch of concrete.

Why does it matter? Carbon, the most commonly used building material in the world, accounts for c. 8% of CO2 emissions globally. The technology used by CarbonCure cuts concrete-related emissions by c. 5%, with an additional 5-10% cut through its wastewater treatment process.

MENA needs to work especially hard to cut its building emissions. MENA’s CO2 output per ton of cement is 35% higher than the global average, World Cement Association CEO Ian Riley said last year, stressing that the region’s cement and construction industries need medium-term targets for 2030, and not just 2050 and 2060 net zero targets. He noted that adopting sustainable processes at cement plants, which will not require significant additional capex, coupled with sustainability policies, could potentially halve the region’s carbon footprint.

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