Durability of 3D Printed Concrete Containing Air-Entraining Agent (2025-11)¶

This study evaluates the carbonation resistance of 3D-printed concrete (3DPC), a critical durability aspect that has received limited attention despite the material’s growing prominence and its known structural reinforcement challenges. The research investigates the influence of air-entraining agents (AEAs) on the carbonation resistance of 3DPC. Carbonation depth was assessed using phenolphthalein solution, and permeability characteristics were evaluated through air content and water absorption measurements. The results indicate that single-layer 3DPC mixtures exhibit inherent resistance to carbonation, with no signs of CO2 penetration. The inclusion of AEAs increased air content by 30–50% in the fresh state and 45–70% in the hardened state, thereby reducing permeability and enhancing durability. Notably, water absorption decreased by 2.4–11.3% in AEA-modified samples over the 0.5-h to 90-d period. Nonetheless, interlayer bonding weaknesses and printing parameters may still pose durability concerns. This study offers new insights into the durability of 3DPC against carbonation, addressing a relatively underexplored aspect of 3D-printed concrete technology and providing practical implications for improving long-term performance in printed concrete structures.