Pilot-Scale Controlled CO2 Curing System for Commercial Concrete Products and Reinforced Concrete Members

Pilot-scale validation of controlled CO2 curing for reinforced concrete members remains limited. This study developed a 2400 L high-temperature CO2 curing chamber integrating control of temperature, relative humidity (RH), CO2 concentration, and pressure with real-time monitoring and automated CO2 regulation. Its applicability was evaluated using commercial concrete bricks and a reinforced concrete slab through mass monitoring, compressive strength testing, phenolphthalein-based carbonation assessment, thermogravimetric analysis (TGA), flexural testing, and carbonation depth measurement. Real-time mass monitoring showed a net mass gain of 50.7 g after 1 h, corresponding to 2.8% of the initial mass. The CO2-cured bricks achieved a compressive strength of 9.77 MPa, with a calculated CO2 uptake of 5.72% based on TGA. The CO2-cured slab exhibited a compressive strength of 41.9 MPa, comparable flexural load capacity to the steam-cured slab, and a higher ductility index of 6.86. Carbonation remained within the concrete cover without reaching the reinforcement. Within the scope of the investigated materials and curing conditions, these results demonstrate the pilot-scale feasibility of controlled CO2 curing for commercial concrete products and reinforced concrete members and provide a basis for further member-scale validation and process optimization.