3D concrete printing of self-supported filaments via entrained cables: constructing formwork-free spanning structures

3D concrete printing (3DCP) enhances design flexibility, reduces construction costs and lowers environmental impact. Traditionally used for wall fabrication, this study introduces a system for printing self-supporting spanning structures using reinforced concrete filaments with tensioned cables, eliminating the need for formwork. The research involved conceptual design and prototyping to integrate cables into the printing process, as well as structural testing of a small-scale model consisting of a reinforced filament. Numerical analysis using the concrete damage plasticity model (CDP) and the traction-separation model simulated the filament's non-linear behaviour and damage. Compared with experimental data, numerical analysis showed good accuracy. Reinforced filaments exhibited a significant increase in flexural strength, from 1.2 kgf·m to 5.0 kgf·m, compared to non-reinforced filaments. Results confirm the feasibility of the proposed method, though challenges remain in ensuring long-term functionality and scalability. Improving the bond between concrete and cables, refining printing parameters and exploring alternative materials are key aspects. While this study focuses on reinforced filaments as proof of concept, future work will address multifilament and multilayer elements like slabs. HighlightsA process for 3D concrete printing spanning structures without formwork was developed.A custom device unwinds cables and prints the concrete filament on top, making it self-supported.Kevlar cables were shown to be compatible with the process, while basalt cables presented difficulties.The flexural strength of cable-entrained filaments improves significantly compared to those without cables. A process for 3D concrete printing spanning structures without formwork was developed. A custom device unwinds cables and prints the concrete filament on top, making it self-supported. Kevlar cables were shown to be compatible with the process, while basalt cables presented difficulties. The flexural strength of cable-entrained filaments improves significantly compared to those without cables.

3D混凝土打印（3DCP）可提升设计灵活性、降低建造成本并减少环境影响。传统上该技术多用于墙体制造，本研究提出了一套采用带张紧线缆的增强混凝土丝材打印自承重跨结构的系统，无需使用模板。本研究开展了将线缆集成至打印流程的概念设计与原型制作，并对含增强丝材的小型模型进行了结构测试。采用混凝土损伤塑性模型（CDP）与牵引分离模型开展的数值分析，模拟了丝材的非线性行为与损伤演化。相较于实验数据，数值分析结果展现出良好的拟合精度。与未增强丝材相比，增强丝材的抗弯强度实现了显著提升，从1.2 kgf·m增至5.0 kgf·m。研究结果证实了所提方法的可行性，但仍需解决保障长期功能与可扩展性的相关难题。优化混凝土与线缆间的粘结性能、调整打印参数以及探索替代材料，均为后续研究的关键方向。尽管本研究以增强丝材作为概念验证核心，但未来工作将聚焦于多丝材与多层构件（如楼板）的相关研究。研究亮点：开发了无需模板的3D混凝土打印跨结构工艺。定制化设备可同步放缆并在其上打印混凝土丝材，实现结构自承重。凯夫拉线缆被证实与该工艺兼容，而玄武岩线缆则存在适配难题。与无线缆增强的丝材相比，内置线缆的丝材抗弯性能得到显著提升。开发了无需模板的3D混凝土打印跨结构工艺。定制化设备可同步放缆并在其上打印混凝土丝材，实现结构自承重。凯夫拉线缆被证实与该工艺兼容，而玄武岩线缆则存在适配难题。与无线缆增强的丝材相比，内置线缆的丝材抗弯性能得到显著提升。