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So apparently it depends on the type of cement - non-hydraulic cement hardens as you described, while hydraulic cement does not absorb CO2 but instead hardens i

So apparently it depends on the type of cement - non-hydraulic cement hardens as you described, while hydraulic cement does not absorb CO2 but instead hardens in the presence of water. I guess they wouldn't have a reason to use hydraulic cement for this though, so it seems you're right.

schiffern 8y ago
It's true that hydraulic cements (eg Portland cement) harden by a different mechanism, but they too will fully carbonatate over time. https://www.astm.org/DIGITAL_LIBRARY/STP/PAGES/STP39460S.htm https://www.astm.org/DIGITAL_LIBRARY/STP/PAGES/STP39460S.htm https://nvlpubs.nist.gov/nistpubs/jres/60/jresv60n5p441_A1b.pdf https://nvlpubs.nist.gov/nistpubs/jres/60/jresv60n5p441_A1b.... https://en.wikipedia.org/wiki/Carbonatation https://en.wikipedia.org/wiki/Carbonatation