论文总字数：32088字

摘 要

ABSTRACT II

第一章 绪论 1

1.1 3D打印混凝土性能 1

1.2 3D打印混凝土工艺参数 2

1.3 国内外研究现状 2

1.3.1 打印工艺 2

1.3.2 材料与打印参数 3

1.4 本文的研究目的和主要目标 5

第二章 原材料与试验方法 7

2.1 原材料 7

2.1.1 水泥 7

2.1.2 纳米二氧化硅 8

2.1.3 砂 8

2.1.4 减水剂 8

2.1.5 水 8

2.2 混凝土配合比 8

2.3 3D打印机 9

2.4 3D打印成型 10

2.4.1 打印参数设置 10

2.4.2 打印程序编写 11

2.4.3 打印成型步骤 12

第三章 纳米二氧化硅掺量对砂浆流变性能及打印效果的影响 13

3.1 流变性测试方法 13

3.2 流变性测试结果 14

3.3 3D打印效果 17

3.4 本章小结 20

第四章 打印参数对打印件强度的影响 21

4.1 打印成型、养护与强度测试方法 21

4.1.1 打印成型与养护 21

4.1.2 强度测试方法 21

4.2 不同打印高度下的砂浆强度 24

4.2.1 抗折强度 24

4.2.2 抗压强度 25

4.2.3 劈拉强度 26

4.3 不同打印速度下的砂浆强度 26

4.3.1 抗折强度 27

4.3.2 抗压强度 28

4.3.3 劈拉强度 29

4.4 本章小结 29

第五章 结论与展望 31

5.1 结论 31

5.2 展望 32

参考文献 33

致 谢 35

摘 要

相较于传统浇注成型混凝土，3D打印混凝土具有智能化、自动化、低人工、无模板等优势，吸引了越来越多学者的关注。但目前对3D打印混凝土性能研究多集中在材料本身，往往忽视了材料与打印工艺参数的协同作用，从而引起一些3D打印混凝土质量不佳，因此，有必要针对3D打印材料性能与打印工艺参数的匹配关系进行研究。

本文研究了纳米二氧化硅掺量变化对打印砂浆的流变参数与打印效果的影响。研究发现在砂浆静态屈服应力、动态屈服应力和塑性粘度等三个流变参数中，静态屈服应力对纳米二氧化硅掺量的变化最为敏感。随着纳米二氧化硅掺量的增加，砂浆静态屈服应力有较为显著的上升，在相同打印参数下打印效果也随之变差。

在流变性能研究的基础上，选取一组打印效果最优的砂浆配比，研究了打印高度与打印速度对打印试件强度的影响，结果表明，当打印高度大于打印条的高度时，打印试件可以获得更高的抗折与抗压强度，而打印高度等于打印条的高度时，打印出的试件的抗折、抗压强度与层间粘结力是最低的。随着打印速度的升高，打印试件的抗折、抗压强度随之降低，抗压强度各向异性也随之增大。同时，3D打印试件的强度是各向异性的。当加载方向与打印层垂直时，试件抗压强度最高；当加载方向与打印层平行时，试件抗压强度最低。

关键词：3D打印混凝土，纳米二氧化硅，静态屈服应力，打印效果，强度

ABSTRACT

Compared with traditional cast concrete, 3D printing concrete has the advantages of intelligence, automation, low labor, no template, and attracts more and more scholars' attention. However, the current research on the performance of 3D printing concrete mostly focuses on the material itself, and often neglects the synergy between materials and printing process parameters, which causes poor print quality in some 3D printing concrete projects. Therefore, it is necessary to study the matching relationship between 3D printing material performance and printing process parameters.

In this paper, the influence of the change of nano-silica content on the rheological parameters and printing results of printing mortar is studied. It is found that the static yield stress is most sensitive to the change of nano-silica content in the three rheological parameters of static yield stress, dynamic yield stress and plastic viscosity of mortar. With the increase of nano-silica content, the static yield stress of mortar has a significant increase, and the printing effect is also worse under the same printing parameters.

Based on the rheological properties research, a set of mortar mixture with the best printing effect was selected to study the influence of printing height and printing speed on the strength of the printed specimens. The results showed that when the printing height was higher than the height of the printing strips, the printed specimens can obtain higher flexural and compressive strength, and when the print height is equal to the height of the print bar, the printed specimens have the lowest flexural strength, compressive strength and interlayer adhesion. As the printing speed increases, the flexural and compressive strength of the printed specimens decreases, and the compressive strength anisotropy also increases. At the same time, the research in this paper also found that the strength of 3D printed specimens is anisotropic. When the loading direction is perpendicular to the printing layer, the compressive strength of the printed specimens are the highest; when the loading direction is parallel to the printing layer, the compressive strength of the printed specimens are the lowest.

KEY WORDS: 3D printing concrete, nano-silica, static yield stress, printing effect, strength

第一章 绪论

3D打印技术是一项新兴技术，又称为“增材制造”，与传统去除材料的加工方式相反，3D打印是基于三维 CAD 模型数据，通过增加材料逐层制造的方式，将“三维” 的零件制造分解成无数“二维”平面的“打印”的制造方式^[1]。

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