Effects of Water-to-Binder Ratios on the Workability, Durability and Strength Development of In-Situ Carbonated Concrete

Enhancing the performance and sustainability of concrete is critical in modern construction, and in-situ carbonation offers a promising approach by introducing CO₂ directly during mixing. This study investigates the influence of CO₂ dosage on the workability, durability, and strength of concrete with varying water-to-binder ratios. Gaseous CO₂ was injected during mixing, leading to the immediate formation of amorphous calcium carbonate and a noticeable reduction in slump within 10 min. Experimental results showed that CO₂ addition improved pore structure and chloride resistance, with reductions of up to 18% in total charge and 13% in migration coefficient. However, a decrease in 28-day compressive strength was observed, varying with mix design. These findings highlight the importance of carefully balancing CO₂ dosage and water-to-binder ratio to enhance durability without compromising long-term strength.