Carbonation Curing versus Steam Curing for Precast Concrete Production

An investigation was conducted into the beneficial utilization of captured CO2 for early-age curing of precast concrete products. The performance of the carbonation-cured concrete was compared to that of steam curing to investigate the possibility of replacing steam curing with carbonation. The early-age carbonation curing was performed for a short period after an initial curing in a controlled environment. The effect of the carbonation curing was studied in terms of carbon uptake, accelerated strength, and durability. It was found that the short-term carbonation promoted early strength development, while subsequent hydration was essential to obtain later age properties. Durability performance of the carbonation-cured concrete was compared with steamed and normally hydrated references. The carbonation-cured concrete exhibited more resistance to chloride permeability, ion migration, sulfate attack, and freeze-thaw damage. The improved durability by carbonation is attributed to the significantly reduced calcium hydroxide content at the carbonated concrete surface. Despite a reduced pH at the carbonated zone, the alkalinity at the core was maintained above the threshold value needed to prevent carbonation corrosion.