Materials and engineering: Rebuilding the world


When Mahoutian started his PhD in civil engineering at McGill University in Montreal in 2011, his goal was to find a material that would sequester carbon, trapping it before it could get into the atmosphere. Instead, he came up with a new recipe for making concrete. “We totally get rid of cement,” he says. “Instead we use slag, the waste material of steel-producing plants.” The slag is calcium silicate. When wet calcium silicate is injected with CO2 gas, calcium carbonate, or limestone, forms. Limestone and the aggregate form Carbicrete.

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