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.
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