Experimental Study of 3D Concrete Printing Configurations Based on the Buildability Evaluation

Different formulations for 3D printable cementitious composites have been developed for extrusion-based printing. However, there is a lack of configuration guides for actual printing operations, which integrate one printable material and one printing system closely. Three testing methods for configuration determination were proposed and tested with three material proportions, with initial setting times of 2, 8, and 13 min, respectively. The building index (BI) measures the layer stacking stability based on the material, scale, and device. The height reduction test (HRT) quantifies the shortening in the height of the printed filaments. The leaning angle (LA) refers to the maximum slope of the stacked layers. In this study, results showed the critical values were (a) 0.167 for the height reduction ratio (HRR), (b) 40° for LA, and (c) 0~19.1, 0~61.1, and 0~99.4 for BI of the three mixtures. They were the meta parameters used to guide the CAD sketching, material development, and printing configurations, including the printing speed and layer height.