Concrete is a leading contributor to global warming and produces as much as 10% of industry-generated greenhouse gas emissions. A new study by Massachusetts Institute of Technology (MIT) (Cambridge, Massachusetts) researchers suggests a way to reduce emissions by more than half while creating a stronger, more durable material. Cement, an integral component of concrete, is made by cooking calcium- and silica-rich materials (limestone and clay) at 1,500 °C to form a hard mass called a “clinker,” which is ground up into a powder. Their analysis indicates that reducing the ratio of calcium to silicate, which is typically anywhere from about 1.2 to 2.2, with 1.7 as the accepted standard, would not only cut greenhouse gas emissions, but would produce better, stronger concrete. As the ratio varies, the molecular structure of the hardened material progresses from a tightly ordered crystalline structure to a disordered glassy structure. When the material is glassier and less crystalline, there are no residual stresses in the material. At a ratio of 1.5, the material can achieve two times the resistance of normal cement in mechanical resistance to fracture. The findings are described in the journal Nature Communications. For more information, visit mit.edu.