论文总字数：24033字

摘 要

在混凝土中掺入纤维可有效改善其力学性能。而普通的纤维增强混凝土中，纤维的取向是随机的，纤维网络是杂乱无章的。对于纤维增强混凝土薄板，纤维以二维的方式分布，有利于提高纤维的利用效率。

为研究定向纤维增强混凝土薄板的制备工艺和力学性能，本文介绍了定向钢纤维增强混凝土的基本工艺与特性，定义了纤维平均等效直径和纤维平均取向角、纤维取向系数和纤维效率系数四个参数来辅助判断纤维的定向效果；设计实验制备了不同钢纤维掺量、不同浇注方式的定向纤维增强混凝土薄板试件，并计划了试验对各组薄板试件进行四点弯曲试验和断面图像分析并计算四个参数，再选取其中有代表性的试件组，测绘薄板的弯曲应力—应变曲线，由以上几种测试方法对比纤维掺量和浇注方式对定向纤维增强混凝土薄板力学性能的影响效果。

最后，关于实验的结果做出了合理预期：

（1）随着钢纤维掺率的增加，钢纤维间相互作用增强，和变大、和变小，但由于钢纤维对基体的增强效果，试件的抗折强度提高；

（2）随着浇注方式的改善，钢纤维的定向效果优化，和变小、和变大，试件的抗折强度也提高；

（3）纤维含率为3vol%的改进浇注方式的两组薄板试件的抗折强度最大，加测四点弯曲试验绘制弯曲应力—应变曲线并进一步分析；

针对定向纤维增强混凝土薄板制备过程中遇到的问题总结了几点经验：

（1）浇注时需保证宽度方向上倒入的浆料量相同、流动速度相同；

（2）控制浆料的粘度并改善其流动性；

（3）手动分层铺放钢纤维时，各层应尽量薄；

并对定向纤维增强混凝土薄板的发展提出合理展望：

（1）完善混凝土薄板的相关国家标准；

（2）拓展研究复合式、层布式纤维增强混凝土中纤维定向的技术；

（3）深入研究将自密实混凝土与纤维定向技术复合；

（4）将纤维定向技术与3D打印混凝土技术复合。

关键词：定向纤维增强混凝土；薄板；纤维取向；浇注方式；力学性能测试

Research on Preparation and Performance of Aligned Fiber-reinforced Concrete Slab

Abstract

Adding fibers to concrete can effectively improve its mechanical properties. In ordinary fiber-reinforced concrete, the orientation of the fibers is random, and the fiber structure is disordered. For fiber-reinforced concrete slabs, fibers are supposed to be distributed in a two-dimensional manner, which is conducive to improving fiber utilization efficiency.

In order to study the preparation process and mechanical properties of aligned fiber-reinforced concrete slabs, this paper introduces the basic process and characteristics of aligned fiber-reinforced concrete , defines 4 parameters - the average fiber equivalent diameter and the average fiber orientation angle , the fiber orientation factor and the fiber efficiency factor - to assist in analyzing the fiber orientation, and designs experiments to produce groups of aligned fiber-reinforced concrete slab specimens with different fiber content and different casting methods. After that some tests are planned, including four-point bending test, cross-sectional image analysis and bending stress-strain curve drawing, to show how fiber content and casting methods influence the properties of slabs.

At the end of the paper, reasonable expectations to results of the experiment are made:

(1) With the increase of the steel fiber content, the interaction between steel fibers is enhanced: and increase while and decrease, but due to the reinforcement of fibers on the concrete matrix, the bending strength of the slabs increases;

(2) With the improvement of the casting method, the orientation of the steel fiber is optimized: and decrease while and increase, and the bending strength also increases;

(3) The bending strength of the two sets of slabs produced by improved casting methods with a fiber content of 3vol% is the highest, and four-point bending tests should be added to draw the bending stress-strain curve and further research should be conducted;

Some experience is summarized in view of the problems faced when producing these slabs:

(1) When pouring the slabs, it should be ensured that the amount of concrete poured in the width direction should be controlled as same amount and flow speed;

(2) When pouring, the viscosity of concrete should be controlled and its fluidity should be improved;

(3) When laying steel fibers manually, each layer should be laid as thin as possible;

Some reasonable ideas and suggestions are proposed on the development of AFRC:

(1) Improve relevant national standards for concrete slabs;

(2) Do more research on fiber orientation technology in composite and layered FRC;

(3) Do more research on the combination of self-compacting concrete and fiber orientation technology;

(4) Composite fiber orientation technology with 3D printed concrete technology.

Key Words: aligned fiber-reinforced concrete; slab; fiber orientation; casting method;

mechanical properties test

目 录

第1章 绪论 1

1.1 研究背景及意义 1

1.2 纤维的掺入对混凝土性能的影响 2

1.2.1 抗压性能 2

1.2.2 抗拉性能 2

1.2.3 抗折性能 3

1.2.4 工作性能 3

1.3 纤维的定向分布 3

1.3.1 纤维定向分布的意义 3

1.3.2 纤维定向分布的方法 4

1.3.3纤维定向分布效果的表征方法与参数 6

1.4 研究内容 8

第2章 实验方案设计 9

2.1 原材料 9

2.1.1 胶凝材料 9

2.1.2 骨料 9

2.1.4 钢纤维 9

2.2 配合比设计 9

2.3 试验设计 10

2.3.1 FRC浇注方式 10

2.3.2 试件的制备 10

2.3.3 试件的测试与性能表征 11

第3章 试验完成概况 13

3.1 标准试件条 13

3.1.1 抗折性能 14

3.1.2 抗压性能 14

3.2 薄板试件 15

第4章 结语与展望 17

4.1 结语 17

4.2 展望 18

参考文献 19

致 谢 22

附录1 23

1. 绪论

1.1 研究背景及意义

1830年前后混凝土的问世，给世界工程材料带来了巨大的变革，其具有的诸多优点如可浇筑性好、经济型号、强度高、耐久性好等，使其成为近现代使用领域最广、使用量最大的土木建筑工程材料。然而，混凝土材料不可避免脆性大、韧性差的缺陷，其抗拉强度和应变较低的缺点限制了其在受到以拉应力为主的载荷和易受极端冲击结构中的应用^[1]。

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