Development of Sustainable Low-Cement Construction 3D Printing Materials via Dense Particle Packing

This study seeks to enhance the sustainability and cost-effectiveness of construction 3D printing (C3DP) as a construction method. A key challenge in C3DP is the excessive Portland cement content (typically >600 kg/m³) of printing materials, increasing construction costs, and the resulting carbon footprint. To address this, an image-based automated gradation system was developed and tested to facilitate particle packing optimization. To design eco-friendly printing materials, large aggregates (up to 3/8 in) and quarry by-products were included as ingredients. The experimental results validated the packing density calculations, showing consistency with theoretical analysis based on the modified Andreasen and Andersen method, and the proposed novel image-based gradation technique. Low-cement (