Not Set in Cement

“Once merely dumped, these ashy-grey, fist-size chunks — called slag — were the unloved scum left over from a century of making steel. But, it turns out, this mountain of waste contains the base ingredients that could make a greener version of one of the major sources of planet-warming emissions today: cement … Cement is the binder that makes concrete — and concrete is the second-most-used commodity on Earth after water. If humans progressed from the Stone to Bronze to Iron ages, it is fair to say that today — by raw tonnage — we are living in a Concrete Age.” WaPo (Gift Article): Reinventing the world’s favorite building material. “Concrete, the second-most-used material on Earth, generates about four times more CO2 emissions than planes.”