Anisotropic Behavior in 3D Printed Concrete (2024-12)¶

After several years of development, 3D concrete printing (3DCP) technology has achieved considerable progress, with many research results in printing equipment, materials, mechanical properties of components, and simulation of printed concrete, which has also made 3DCP more controllable. The results showed that the mechanical properties of 3D printed concrete (3DPC) had obvious anisotropy according to the printing path. This article aims to provide a concise overview of the mechanical variations in 3DPC, specifically focusing on its anisotropic performance. It delves into the distinctions observed among various researchers who employ different printing materials, equipment, and associated printing parameters. We summarize the causes of anisotropy and introduce three present numerical simulation approaches for printed concrete. These methods involve utilizing anisotropic equivalent elements, employing defective layers with thickness, and integrating zero-thickness cohesive elements to mimic the behavior of 3DPC. In addition, this article will also compare above-mentioned three methods with the cube compression test of 3DPC. The findings show that the strength simulation values of the defect layer with thickness method in the X and Y directions are closest to the actual values, with deviations of only 3.7% and 0.7%, respectively, and the Z direction is slightly higher. The results of the zero-thickness cohesive element method are all higher than the experimental values. The results show that anisotropic equivalent elements method has the best computational efficiency, but cannot simulate the interlayer damage between concrete strips. Both defect layer with thickness method and zero-thickness cohesive element method could simulate interlayer damage; the former method has the best accuracy in strength and damage simulation, the latter one has a faster computing speed and easier modeling. This article can provide reference for future research on 3DPC simulation and select more suitable simulation methods based on different types of 3D printing structures and analysis focuses.