While lime production does give off approximately the same amount of CO2, lime (plasters, mortars etc) harden via recarbonation, reabsorbing the CO2 it gave off during it's production (not including fuel emissions). Portland cement hardens via hydration, where it reacts with water - the CO2 driven off the limestone in production is never recaptured.
While lime production does give off approximately the same amount of CO2, lime (plasters, mortars etc) harden via recarbonation, reabsorbing the CO2 it gave off during it's production (not including fuel emissions). Portland cement hardens via hydration, where it reacts with water - the CO2 driven off the limestone in production is never recaptured.