3 ms·
Portland cement is at least 80% CaO, so in theory it's 63% of the cement's dry mass (CaO + CO2 -> CaCO3)[1]. In practice it's ~43% that value, or 27% of the cem
by schiffern 8y ago
Portland cement is at least 80% CaO, so in theory it's 63% of the cement's dry mass (CaO + CO2 -> CaCO3)[1]. In practice it's ~43% that value, or 27% of the cement's dry mass.[2]
[1] https://en.wikipedia.org/wiki/Cement_kiln#Carbon_dioxide https://en.wikipedia.org/wiki/Cement_kiln#Carbon_dioxide
[2] https://www.nature.com/articles/ngeo2840 https://www.nature.com/articles/ngeo2840
- MauranKilom 8y agoSo 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 agoIt'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