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The cement industry generates three times more carbon emissions than the aviation industry, the bulk of which come from limestone, which releases CO2 when processed. Manufacturer Brimstone swapped limestone for calcium silicate rock, which is not only far more abundant, but produces a byproduct that absorbs CO2, making the company’s cement effectively carbon negative. In July, Brimstone became the first in the industry to receive third-party certification that its product is as strong as standard cement. The company is now looking to scale up. “It shows the industry that there’s a solution coming,” says Brimstone co-founder Hugo Leandri.

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