Concrete is the world's most-used construction material, and a leading contributor to global warming, producing as much as one-tenth of industry-generated greenhouse-gas emissions. Now a new study suggests a way in which those emissions could be reduced by more than half -- and the result would be a stronger, more durable material. The findings come from the most detailed molecular analysis yet of the complex 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. These findings are described in the journal Nature Communications by MIT senior research scientist Roland Pellenq; professors Krystyn Van Vliet, Franz-Josef Ulm, Sidney Yip, and Markus Buehler; and eight co-authors at MIT and at CNRS in Marseille, France.A 50% reduction in emissions, combined with a stronger and more durable material, is a huge boon! To read more, click here.