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Concrete absorbs carbon dioxide even after it's set? Shouldn't it like... grow, then? From accumulated carbon? Don't mean to waive you off or anything, just ne
by beaner 6y ago
Concrete absorbs carbon dioxide even after it's set? Shouldn't it like... grow, then? From accumulated carbon?
Don't mean to waive you off or anything, just never heard this before and it doesn't seem to make sense at first listen.
- elihu 6y agoI don't much about biosphere 2 specifically, but I have read that concrete absorbs CO2 over long timescales. Hundred-year-old concrete is chemically different than it was when it was a month old. I don't know if it gets denser, or if the CO2 replaces something else.
- snypher 6y agoConcrete samples from inside and outside the structure showed strikingly different levels of calcium carbonate, which was rapidly being formed inside the domes as huge amounts of carbon dioxide reacted with calcium hydroxide in the concrete. ... Severinghaus said of the calcium carbonate. "It's 10 times more than outside." From https://www.nytimes.com/1993/10/05/science/too-rich-a-soil-scientists-find-the-flaw-that-undid-the-biosphere.html https://www.nytimes.com/1993/10/05/science/too-rich-a-soil-s...
- beaner 6y agoBut how much was it relative to the total volume of concrete?
- krisoft 6y ago“ Concrete continues to set and cure for months and years, increasing its strength over time. It's a long-lived giant chemical reaction that continues on long after it has set.” Source: https://interestingengineering.com/why-concrete-doesnt-actually-dry-out https://interestingengineering.com/why-concrete-doesnt-actua...
- beaner 6y agoBut it continues to take up the same volume of space, so isn't there a limit to how much carbon dioxide it can remove from the atmosphere and store?
- krisoft 6y agoYes of course it has a limit. Nobody said that it is an infinite sink. If you are interested in the details I can recommend J.P. Severinghaus et al., “Oxygen loss in Biosphere 2“.
- beaner 6y agoI'm just surprised because somebody said that the concrete soaked up so much carbon that the trees alongside it in the biosphere were unable to grow. That sounds like a lot of carbon. Like, a lot. I'd expect that it would have to absorb enough carbon that it could displace some amount of the volume that it would have appeared as in tree form. Can you fit a third of a small forest into the concrete around that small forest? It seems unlikely.