水泥基材料3D打印构件体积稳定性优化方法研究
易幸存
摘 要
3D打印建造技术，将3D打印与传统建造行业相结合，已成为促进传统建造业转型升级以及实现智能建造的关键技术。建造行业最常用的材料是水泥基材料，运用水泥基材料进行3D打印，是当前业内的重要研究方向，研究者们在近年来取得了较多突破性的进展。然而，在水泥基材料3D打印构件的相关研究中，对构件体积稳定性的控制一直是个难题。水泥基材料3D打印构件的体积稳定性控制包括打印堆叠过程中的变形控制与硬化后的收缩调控。文章分析构件变形性能的影响因素，提出变形控制理论模型；分析材料配比控制收缩性能，提出构件收缩调控方案；设计材料实验和打印实验，实现对构件体积稳定性的控制与优化。
本文提出构件打印堆叠过程变形控制理论模型并进行验证。推导出外力变形量的数学表达式，表明外力变形量与层间打印间隔时间、构件层数和单层构件重量等因素有关，并在实验中通过提高材料经时承载性能、调节层间打印间隔时间对构件外力变形量进行控制。构件自体变形量则通过调节材料配比进行调控。
为控制构件收缩，本文通过大量的材料实验数据分析，得出在选择水泥基材料时应优先考虑促凝剂、胶凝材料体系和纤维的掺量及配比的结论，提出3D打印构件硬化体收缩调控方法。
根据本文提出的打印堆叠过程变形控制理论模型与硬化体收缩调控方法，指导3D打印前的材料性能选择和打印工艺设计，将构件的变形和收缩控制在合理范围内，达到提高3D打印构件的品质的目标。
关键词：水泥基材料；3D打印构件；体积稳定性；材料性能；打印工艺参数
Abstract
3D printing construction technology, which combines 3D printing technology with traditional construction industry, has become the key technology to promote the transformation and upgrading of traditional construction industry and realize intelligent construction. Cement-based materials are the most commonly used materials in construction industry. Using cement-based materials for 3D printing is the main research direction in the industry, and researchers have made large quantities of breakthroughs in recent years. However, in the research of 3D printing components of cement-based materials, it is always a difficult problem to control the volume stability performance of components. Control to the volume stability performance of cement-based 3D printing components includes control to deformation during printing and stacking, and shrinkage regulation after setting and hardening. Meanwhile, the influence factors of components deformation were analyzed, and the theoretical model of deformation control was put forward. After analyzing material mixture ratio to control the shrinkage, the regulation scheme of shrinkage was proposed. Finally, the material experiments and printing experiments were designed to control and optimize the volume stability performance of components.
In this thesis, the theoretical model of deformation control in the 3D printing stacking process was proposed and verified. The mathematical expression of components deformation by compressive stress was derived, and it shows that the deformation by compressive stress was related to factors such as inter-layer printing interval time, number of layers of components and weight of single-layer components. The deformation by compressive stress of components was controlled by improving the time-varying bearing capacity of cement-based materials and adjusting inter-layer printing interval time. The self-deformation performance of components was regulated by adjusting material mixture ratio.
In order to regulation the printing components shrinkage, this thesis draws a conclusion that the amount and proportion of accelerator, cementitious material system and fibers should be given priority in selecting cement-based materials through a large number of experimental data analysis. The regulation scheme of shrinkage for 3D printing components of cement-based materials was put forward.
According to theoretical model of deformation control in 3D printing stacking process, and regulate scheme of shrinkage after setting and hardening of 3D printing components of cement-based materials, the material performance selection and technical parameters design before printing could be guided. The deformation and shrinkage of components could be controlled and regulated within a reasonable range to achieve the goal of improving the quality of 3D printing components.
Keywords: Cement-based materials; 3D printing components; Volume stability performance; Material performance; Printing technical parameters
国家数字建造技术
创新中心
