Effect of CO2 Curing on the Carbonation Performance of Concrete

MA Congcong; YANG Changhui; BAI Yun; XU Tao; YU Linwen

doi:10.3969/j.issn.1007-9629.2026.02.007

Abstract：This study investigated the effect of CO2 curing on the carbonation performance of concrete by comparing the changes in compressive strength,carbonation rate,product composition,and micromorphology between CO2-cured and conventionally cured concrete at different carbonation ages.The results indicate that CO2 curing significantly influences the microstructural evolution of concrete.Compared with the traditional carbonation model(carbonation index λ=0.50),the relationship between carbonation depth and carbonation age for CO2-cured concrete is better described by a power function model with λ=0.21.In the early carbonation stage(<150 d),CO2-cured concrete exhibits a high carbonation rate and a fast increase in compressive strength.The high carbonation rate is mainly attributed to the partial consumption of clinker minerals during CO2 curing,which to some extent inhibits subsequent hydration and reduces the number of carbonatable substances.In the later carbonation stage(>150 d),carbonation products fill the pores,thereby reducing porosity and hindering CO2 diffusion into the matrix.At the same time,the continued hydration in the uncarbonated regions generates a large amount of hydration products,which effectively slows down the carbonation process,leading to a significant decrease in the carbonation rate.