Influence of Coarse Aggregates on the Performance of 3D Printing Concrete (2024-09)¶

Compared with traditional construction technology in terms of the building structure, 3D printing concrete (3DPC) technology offers significant advantages such as high efficiency, reduced labor costs, and minimized construction waste. As a result, concrete 3D printing has emerged as a prominent trend in the civil engineering industry. However, the current use of 3DPC in engineering applications predominantly relies on mortar, which suffers from significant shrinkage and a propensity for cracking. To overcome the shortcomings of low strength and notable shrinkage of 3DPC, this study incorporated coarse aggregates into 3DPC and clarify the influence of different size aggregates on the performance of 3DPC. Experimental research on 3D printed concrete with coarse aggregates was conducted, and the influence of different particle sizes of coarse aggregates on the workability such as flowability, extrudability, printability, and constructability were figured out. Based on the findings, optimal mix proportions were determined. Mechanical tests were conducted to characterize the effects of printing paths and loading directions on the performance of 3DPC with coarse aggregate. The influence of aggregate particle size on the strength, elastic modulus, and stress-strain behavior of 3D printed concrete was also elucidated. Additionally, microscopic tests were employed to analyze the internal pore characteristics, revealing the influence of factors such as porosity, pore size, and spatial morphology on the mechanical properties and providing insights into the anisotropic mechanism of 3DPC.