基于波浪形打印路径的3DPC-NC结构体系力学性能

Mechanical properties of 3DPC-NC structural system based on wavy printing path

  • 摘要: 混凝土3D打印技术因其无模化特性在装配式建筑中展现出显著优势,其免拆模特点是传统工艺无法比拟的。然而,该技术特有的逐层堆积工艺会在3D打印混凝土(3DPC)的层间及条间形成薄弱区。当大量薄弱区位于同一截面时,易引发集中破坏,对构件整体安全性构成隐患。不同的打印路径可有效调控条间薄弱区的分布特征。本研究创新性地提出一种波浪形打印路径,旨在分散各层打印条间的界面薄弱区,避免其上下层对齐于同一截面。通过调控波浪扭曲幅度(以打印路径曲率角为变量),系统评估了该路径对3DPC抗压性能、各向异性及条间粘结性能的影响,验证了其在无额外成本前提下提升3DPC力学性能的可行性。同时,探究了打印路径对界面性能的作用机制。结果表明:采用波浪形路径的3DPC,其整体性能(尤其在各向异性和条间抗拉强度方面)显著优于传统直线路径。条间抗拉强度随曲率角增大呈指数增长;当曲率角为90°时,条间界面粘结强度达2.48 MPa,较传统路径提升52.34%。3DPC-NC界面过渡区的抗压强度与各向异性的变化趋势与3DPC本身基本一致,界面抗拉强度在曲率角为70°时,粘结强度达到最大值为2.82 MPa,较传统路径提升36.89%。基于试验数据,建立了3DPC条间界面抗拉粘结强度和3DPC-NC界面抗拉粘结强度的预测模型,其预测精度良好,为混凝土3D打印技术的发展提供了有价值的理论参考。

     

    Abstract: Concrete 3D printing technology has shown significant advantages in prefabricated buildings due to its non-molded characteristics, and its demolition-free model points are incomparable with traditional processes. However, the technology's unique layer-by-layer stacking process creates weak zones between layers and strips of 3D printed concrete (3DPC). When a large number of weak areas are located in the same cross-section, it is easy to cause concentrated damage, which poses a hidden danger to the overall safety of the component. Different printing paths can effectively control the distribution characteristics of weak areas between strips. In this study, a wavy printing path is innovatively proposed, which aims to disperse the interface weak areas between the printing strips of each layer and avoid the upper and lower layers from aligning with the same cross-section. By adjusting the wave twist amplitude (with the curvature angle of the printing path as the variable), the effects of the path on the compressive performance, anisotropy, interlayer adhesion and inter-strip adhesion properties of 3DPC were systematically evaluated, and the feasibility of improving the mechanical properties of 3DPC without additional cost was verified. At the same time, the mechanism of printing path on interface performance is explored. The results show that the overall performance of 3DPC with wavy path (especially in terms of anisotropy and tensile strength between strips) is significantly better than that of traditional straight path. The inter-strip tensile strength increases exponentially with the increase of curvature angle. When the curvature angle is 90°, the inter-strip interface bonding strength reaches 2.48 MPa, which is 52.34% higher than that of the traditional path. The tensile strength of the interface is 2.82 MPa at the curvature angle of 70°, which is 36.89% higher than that of the traditional path. Based on the experimental data, a prediction model for the tensile bond strength of the 3DPC interstrip interface and the tensile bond strength of the 3DPC-NC interface was established, which had good prediction accuracy and provided a valuable theoretical reference for the development of concrete 3D printing technology.

     

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