Unlocking the Sustainable Potential of 3D Concrete Printing with Large Aggregates and Steam–CO2 Curing (2025-10)¶

Three-dimensional concrete printing (3DCP) has emerged as a promising innovation in the construction industry, significantly reducing its reliance on intensive labor while minimizing material waste. Despite its benefits, a major limitation of current 3DCP practices is the high reliance on cement as the primary binder, which often exceeds 60% of the total solid content. This high cement usage contributes significantly to CO2 emissions, raising sustainability concerns. In this study, a 3D-printable concrete mix incorporating large aggregates (up to 10 mm) was developed, replacing over 7% of fine aggregate and reducing cement content to approximately 29% by weight. The effects of CO2 gas and a steam–CO2 mixture on the mechanical performance and CO2 uptake of the printed concrete were assessed. Thermogravimetric analysis was used to quantify CO2 sequestration over time. Compared to control samples without gas treatment, those exposed to the steam–CO2 mixture showed enhanced buildability, improved compressive and flexural strength, and greater CO2 uptake. The results suggest that surface spraying of the steam–CO2 mixture during the 3D printing process offers a viable and scalable approach to improving both the structural performance and environmental footprint of printed concrete elements.