But the re-absorbed CO2 will come from new limestone dissolving into calcium bicarbonate, not from atmospheric CO2.

You'll be adding more CO2 to the air -increasing oceanic acidification- while increasing the ocean's ability to dissolve more CaCO3. Far from fighting global warming it sounds like this will put exactly as much CO2 into the atmosphere and double the leaching impact on shellfish and coral.

I am shit at chemistry and would really like cement to not release CO2, but I don't understand this.