Quality Assessment of 3D‐Printed Concrete Through Quantitative Visual Inspection (2025-07)¶

3D concrete printing is an advanced technology offering numerous benefits, including design flexibility, higher construction efficiency, and reduced labor cost. However, the unique processing requirements necessitate careful consideration of the quality of 3D-printed concrete. To this end, this study developed a real-time visual inspection method to quantify geometrical and surface quality metrics, integrating rheological parameters for enhanced accuracy. Three binder-to-sand ratios (0.6, 0.8, 1) and sand fineness moduli (2.5, 2.9, 3.3) were tested. We began by comparing various image processing technologies, followed by analyzing the geometrical contour and surface defects from a top-down perspective. Results showed that increasing the binder-to-sand ratio from 0.6 to 1 and reducing the sand fineness modulus from 3.3 to 2.5 reduced defect area ratios by up to 98% (from 4.3% to 0.041%). Subsequently, we integrated rheological parameters to refine the image analysis results and validated the approach through three case studies. The results demonstrate that the developed visual inspection technology effectively assesses the quality of 3D-printed concrete, ensuring precision and reliability in evaluating 3D-printed structures.