This post on a product designer’s foray into making a much more Earth-friendly concrete gives me hope for humanity. It’s estimated that about 5% of greenhouse gasses are released due to the existing process of making the cement in traditional concrete. The new process, dubbed “Dupe,” uses approximately none (although I’m sure a fair amount does go into the mass production of urea, which is a major component of fertilizer).
Turns out, all you need is some sand, bacteria, calcium chloride and a decent amount of urea.
The reason I think Dupe is so much better is because it only requires “biological temperatures” (I suppose that means 80-100°F), as opposed to the thousands of degrees needed to make calcium carbonate and clays react to form cement. The only real downside I see at this point is that structurally, Dupe concrete is only about 2/3 as strong as traditional concrete. But come on, I know some smart materials science people must want to get in on this and try to make it even better.