Concrete emissions could be reduced by as much as 60 percent — and the result would be a stronger, more durable material, according to a study published in the journal Nature Communications by Massachusetts Institute of Technology researchers.
The findings come from a detailed molecular analysis of the structure of concrete, which is a mixture of sand, gravel, water and cement. Cement is made by cooking calcium-rich material, usually limestone, with silica-rich material — typically clay — at temperatures of 1,500 degrees Celsius, yielding a hard mass called “clinker.” This is then ground up into a powder. The decarbonation of limestone, and the heating of cement, are responsible for most of the material’s greenhouse-gas output.
The new analysis suggests that reducing the ratio of calcium to silicate would not only cut those emissions, but would actually produce better, stronger concrete.
In July startup company Solidia Technologies and the US Department of Energy’s National Energy Technology Laboratory partnered to accelerate the development of cement that can reduce the carbon footprint of concrete by up to 70 percent.