Transforming Construction Waste into Resources for 3D Printed Concrete (2025-07)¶

The construction sector faces significant challenges in balancing environmental sustainability, economic feasibility, and compliance with required strength standards. This study investigates the potential of recycled materials, specifically waste concrete fine aggregates (WCA), for use in geopolymer mortar for 3D concrete printing as a sustainable alternative to conventional construction methods. The research examines the fresh and hardened properties of 3D-printed geopolymer mortar. Experimental results demonstrate that WCA-based mixtures achieve superior compressive strength and dimensional stability compared to natural fine aggregates (NFA). Life cycle analysis (LCA) further highlights the environmental benefits of WCA-based 3D mixture, showing a 3.4% reduction in global warming potential (GWP) and a decrease in terrestrial acidification compared to NFA. The study also underscores the importance of orientation in 3D printing, with significant improvements in compressive strength observed in all tested directions: perpendicular (64.2%), lateral (77.2%), and longitudinal (57.7%). This research emphasizes the promise of 3D concrete printing with recycled materials as a transformative approach to sustainable construction, reducing environmental impacts while maintaining structural performance.