[conservatism_IS_compassion]

use less concrete, decreasing not only weight but also the energy required to make it and the carbon emissions associated with cement’s manufacture.

If I knew anything about chemistry, I would say that limestone is CaCO₃. And that cement is produced by causing limestone to dissociate under heat into CaO and CO₂. So much would agree with the statement above.

OTOH if I knew anything about chemistry I would say that when cement sets, the reverse reaction occurs and CaO and CO₂ from the atmosphere combine to form CaCO₃. But that can’t be right, because the article clearly indicates that using cement is a net addition of CO₂ to the atmosphere.

[dangerdoc]

Takes a bunch of natural gas to cook limestone into cement. I think I remember hearing about a cement plant fired with old tires, now that would be nasty.