[innocentfelon]

I wish more people realized the concrete thing is snake oil.

When you make cement, you heat up natural CaCO3 -> CaO + CO2. The heat itself also requires combustion, so more CO2.

Some cements have perhaps 10% CaCO3 added to their mix. It’s not so much desirable as cheap filler.

What the media fails to realize is pumping CO2 into curing cement reverses the CaO reaction. In other words, every CO2 molecule you capture releases 2 or more. You’d be better off using less CaO and more CaCO3 to begin with.

[raverbashing]

Read the page of the company doing it, that's not exactly what they're doing (which you correctly point out it would be pointless) - http://www.blueplanet-ltd.com/

[innocentfelon]

I read it again, twice. That is exactly what they’re doing.

Their starting material is CO2-source cement, not some natural “rock”.

Counterexamples are substantially more helpful than downvotes.

[raverbashing]

It seems they're not replacing the quicklime, but the gravel. The left column is confusing, the right column is better.

> A rock particle is coated with our synthetic limestone, forming a carbon-sequestering coating that is 44% by mass CO2.

That's where the CO2 goes, not in curing the CaO

[08-15]

But where does the Ca come from? Obviously not from limestone...

[liveoneggs]

so you're claiming this isn't a functional perpetual motion machine that (bonus) outputs useful building materials? come on

[ksec]

How about this?

https://money.cnn.com/2018/06/12/technology/concrete-carbonc...