Cement manufacturing (such as that at this plant in Russia) accounts for 8% of the world’s carbon dioxide emissions. Credit: Getty Wet concrete has been poured into buildings, roads, bridges and ...

If the cement industry were a country, it would be the third-largest emitter of carbon dioxide in the world, after the U.S. and China. One startup seeks to change that.

T he world gets a little greyer every year. According to a paper published in 2014 concrete—an aggregate material made by mixing cement, sand and gravel—is the second-most consumed substance ...