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A number of innovators are working to clean up the world’s leading building material by pumping it full of CO2. One such process—from Dartmouth, Nova Scotia–based CarbonCure—has already caught on with project teams, and a California-based competitor is hot on its heels with a complementary approach. Combined with some more established lower-tech tricks, these processes could trim concrete’s embodied carbon by over 80 percent.
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Juan Gonzalez, sustainability manager for operations at San Jose–based Central Concrete, says his firm routinely uses CarbonCure’s process with concrete mixes that have high ash and slag content. He points to the floors that Central Concrete poured last year for the SOM-designed new San Francisco law building at the University of California, Hastings. For that job they added CO2 to concrete with a 55:45 ratio of Portland cement to substitutes, cutting embodied carbon in half relative to conventional concrete.