Multi-response optimization of early-age CO2 curing conditions for enhanced carbon sequestration and performance of concrete

This study investigates the synergistic effects of curing temperature, relative humidity (RH), and CO 2 concentration on early-age CO 2 sequestration, mechanical performance, and durability of concrete. A central composite design and response surface methodology (RSM) coupled with desirability function analysis were employed to optimize curing conditions. CO 2 uptake was quantified through weight change, thermogravimetric analysis (TGA), and carbonation depth, while mechanical performance was evaluated by compressive strength at 2 and 28 days, and durability by chloride diffusion coefficient. Results showed that higher temperatures significantly enhanced carbonation efficiency and strength development by accelerating moisture evaporation and ion transport. Weight change exhibited the strongest correlation with compressive strength, whereas TGA measurements were more susceptible to sampling variability. No clear correlation was found between CO 2 uptake and chloride diffusion coefficient, suggesting complex pore-level interactions. The optimal curing conditions of 80 °C, 44.8% RH, and 50.7% CO 2 concentration achieved the highest composite desirability (0.88), balancing CO2 sequestration, strength, and durability.