Abstract
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.
Highlights
Compared with traditional building construction, 3D concrete printing (3DCP) technology has the following potential advantages: (1) high degree of mechanical automation with short construction times, safety, cleaning, and accuracy; (2) no frame required, and resource consumption is relatively reduced; (3) labor-saving; (4) light weight, high strength and multi-functionality can be achieved through structural design; and (5) high customization can realize both standardization and personalization in construction products
This study proposes buildability evaluation methods for a printing operation in terms of the printable material (PM), printing device (PD), and printed object (PO)
It is believed that the material proportion and the printer achieved acceptable printability, with accurate mechanical positioning, controllable extruding operation, and stable material properties, based on which the buildability could be further studied
Summary
Three-Dimensional printing technology with digital, customized, and new material features is a promising emerging technology. After more than 20 years of development, 3D printing technology has been used in many fields such as aerospace, medical equipment, metal parts, etc., with its high accuracy, short production cycle, and diverse materials [1,2]. Compared with traditional building construction, 3DCP technology has the following potential advantages: (1) high degree of mechanical automation with short construction times, safety, cleaning, and accuracy; (2) no frame required, and resource consumption is relatively reduced; (3) labor-saving; (4) light weight, high strength and multi-functionality can be achieved through structural design; and (5) high customization can realize both standardization and personalization in construction products. The material should possess the following characteristics: (1) have good fluidity to be pumped from a remote container, (2) can be extruded from a nozzle to the printing bed, (3) keep its finished shape with neither obvious fractures nor cracks [7],
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