Effect of pre-conditioning on CO2 curing of lightweight concrete blocks mixtures

It is a common practice to use steam to cure precast concrete products and concrete masonry blocks after casting. Steam curing is an energy extensive process and contributes significantly to the production costs. This study investigated the effects of pre-conditioning on the CO2 curing of lightweight concrete block mixtures. The results indicated that there was an optimum moisture loss at which the specimens demonstrated the highest strength and CO2 consumption after CO2 curing. However, the moisture evaporation rate had to be controlled so to avoid plastic shrinkage cracking. CO2 curing was an exothermal process, which raised the temperature of specimens very quickly within a short period of time. Traditional steam curing of concrete blocks took 18–24 h, CO2 curing could be completed with 4–8 h including pre-conditioning to achieve strength equivalent to that steam curing, This means that the use of CO2 curing technology has advantages not only in reducing and/or utilizing greenhouse gas emissions, but also in decreasing the curing time and increasing productivity of plain and non-steel reinforced concrete products.