Making cement is the third largest source of carbon emissions in the world after the burning of fossil fuels and deforestation—but the Australian roads of the future could be paved with cement that is made in a process that generates less than half the carbon emissions of traditional methods.

Each year, the world produces about 12 billion tonnes of concrete and about 1.6 billion tonnes of its key ingredient, Portland cement, which is generated by breaking calcium carbonate into carbon dioxide and calcium oxide.

This produces some 2 billion tons of carbon dioxide—so the Geopolymer and Mineral Processing Group (GMPG) at the University of Melbourne, now led by Dr John Provis, went looking for a lower carbon way of making cement.

They have now developed binders and concretes based on a low-CO₂ aluminosilicate compounds called geopolymers.

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