3 ms·
The reason why is you are wrong. Portland cement, when hardened, does not absorb any significant amount of CO2. It does not form limestone. It mostly forms CSH
by coryrc 7y ago
The reason why is you are wrong.
Portland cement, when hardened, does not absorb any significant amount of CO2. It does not form limestone. It mostly forms CSH [0] which just takes water, silicon dioxide, and quicklime. The last is sourced from limestone but does not turn back into limestone.
[0] https://en.wikipedia.org/wiki/Calcium_silicate_hydrate https://en.wikipedia.org/wiki/Calcium_silicate_hydrate
- excessive 7y agoAcross the world, what percentage is Portland cement vs the other CO2 absorbing kind? I googled around, but couldn't find the answer.
- aidenn0 7y agoPer TFA, 98% of concrete is made from Portland cement.
- CalRobert 7y agoNearly all, much to the frustration of heritage building owners everywhere. I just spent a few weeks manually chiselling off a godawful cement render from a wall to restore a naturally-hydraulic-lime based one. The cement crap is rock-hard and doesn't have any moisture permeability, so water gets in and just dissolves your building (or more importantly, the old lime-based mortar holding up the dozens of tonnes of stone that is your home)
- Symmetry 7y agoAnd basically all the other forms of cement in use starting with the Romans. https://rootsofprogress.org/cement-redux https://rootsofprogress.org/cement-redux