Better Cement mixture would make it twice as strong and allow less to be used and reduce carbon emissions by 60 percent

“Cement is the most-used material on the planet,” Pellenq says, noting that its present usage is estimated to be three times that of steel. “There’s no other solution to sheltering mankind in a durable way — turning liquid into stone in 10 hours, easily, at room temperature. That’s the magic of cement.”

In conventional cements, Pellenq explains, the calcium-to-silica ratio ranges anywhere from about 1.2 to 2.2, with 1.7 accepted as the standard. But the resulting molecular structures have never been compared in detail. Pellenq and his colleagues built a database of all these chemical formulations, finding that the optimum mixture was not the one typically used today, but rather a ratio of about 1.5.

As the ratio varies, he says, the molecular structure of the hardened material progresses from a tightly ordered crystalline structure to a disordered glassy structure. They found the ratio of 1.5 parts calcium for every one part silica to be “a magical ratio,” Pellenq says, because at that point the material can achieve “two times the resistance of normal cement, in mechanical resistance to fracture, with some molecular-scale design.”

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