论文总字数：31327字

摘 要

混凝土工程的发展使人们对传统混凝土材料出现了新的更高的要求。因此当代混凝土材料科学工作者将目光投向了研发具有高性能和优异功能的混凝土材料。而使用优质的外加剂已被公认为是得到高性能混凝土的最重要技术之一。已有研究表明，人为地在混凝土中加入能够促进水泥水化成核的纳米粒子，可以使水泥水化进程显著加快，并且纳米水化硅酸钙（C-S-H类凝胶）颗粒促进水化进程效果最好。因此，掺纳米C-S-H凝胶颗粒正逐渐成为一种新的提高水泥混凝土早期强度的新技术，受到越来越广泛的关注。而C-A-S-H凝胶是硅酸盐水泥中的Al³ 对C-S-H凝胶中Si⁴ 进行取代和进入结构层间平衡结构电荷形成的水化硅铝酸钙。因此其在硅酸盐水泥中具有类似于C-S-H凝胶的作用。并且从已有的研究中可以推断出，含Al元素的C-A-S-H凝胶可以使得水泥基材料的耐久性、耐蚀性以及后期强度提高。但当前，关于合成C-A-S-H凝胶对普通硅酸盐水泥性能影响的研究几乎为空白。本研究可为合成C-A-S-H凝胶的实际应用提供理论支持。

本实验通过水热合成法制备C-A-S-H凝胶，使用XRD、SEM表征手段研究不同CaO/SiO₂、相同温度和养护时间情况下C-A-S-H凝胶微观结构、化学组成等性能方面的差异，从而确定最佳原料比例。然后采用水泥强度测试仪、SEM、水化热测试、压汞测试等手段研究合成C-A-S-H凝胶对普通硅酸盐水泥初凝和终凝时间、力学强度、水化产物微观形貌、水化放热过程、孔隙状态的影响。

对合成C-A-S-H凝胶的基础表征表明，CaO/SiO₂为1.0时合成C-A-S-H凝胶结晶度最好，并且纯度较高，所以后续实验均采用CaO/SiO₂为1.0的样品；同时CaO/SiO₂为1.0的合成C-A-S-H凝胶为团聚的不规则絮状颗粒结构，疏松且多孔。对合成C-A-S-H凝胶改性普通硅酸盐水泥基本性能的研究表明，加入合成C-A-S-H凝胶能显著缩短普通硅酸盐水泥凝结时间；并且掺入一定量的合成C-A-S-H凝胶可以在一定程度上提高普通硅酸盐水泥的抗压及抗折强度，当掺入量为1%时对抗折强度的提升量最大，对抗压强度的提升也很不错，但是，当掺入量过大时，普通硅酸盐水泥的强度反而会出现下降。此外，掺入合成C-A-S-H凝胶的数量及养护时间均对水泥水化产物影响不显著；加入合成C-A-S-H凝胶可以促进水泥中纤维状C-( A) -S-H凝胶的生成，并且合成C-A-S-H凝胶掺入的越多，纤维状物质数量越多，分布越致密；加入合成C-A-S-H凝胶使得普通硅酸盐水泥水化放热量增加，加速阶段提前，加速了水泥的水化过程。

关键词：C-A-S-H凝胶 普通硅酸盐水泥 改性 水泥水化 早期表现

Synthesis of C-A-S-H minerals and its effect on the properties of cement-based materials

ABSTRACT

The development of concrete engineering has placed new and higher requirements on traditional concrete materials. Therefore, the development of high-performance, high-functionality concrete materials has become the direction and focus of contemporary concrete materials science and engineering research. The use of high-quality admixtures has been recognized as the one of the most important technical means to achieve high performance of concrete. Studies have shown that artificially adding nanoparticles that promote cement hydration nucleation can significantly accelerate the hydration process of cement, and nano-hydrated calcium silicate (C-S-H gel) particles promote the hydration process fastest. Therefore, nano-doped C-S-H gel particles are gradually becoming a new new technology to improve the early strength of cement concrete, and have received more and more attention. The C-A-S-H gel is a hydrated calcium aluminosilicate formed by the substitution of Al³ in the Portland cement for Si⁴ in the C-S-H gel and into the equilibrium structure charge between the structural layers. It therefore has a similar effect to the C-S-H gel in Portland cement. And from the existing research, it can be seen that the C-A-S-H gel rich in Al can improve the late strength, durability and corrosion resistance of the cement base. However, at present, the research on the effect of synthetic C-A-S-H gel on the performance of Portland cement is almost blank. This research will offer theoretical support to the practical application of synthetic C-A-S-H gel.

In this experiment, C-A-S-H gel was prepared by hydrothermal synthesis method. SEM and XRD characterization methods were used to study the differences in the properties of C-A-S-H gel microstructure and chemical composition under different CaO/SiO₂, same temperature and curing time. Then we used test methods like cement strength tester, SEM, hydration heat test, mercury intrusion test, etc. to study the mechanical strength, microstructure, setting time, hydration process, porosity and pore distribution of the Portland cement added synthetic C-A-S-H gel.

The basic characterization of the synthetic C-A-S-H gel showed that the CASH gel had the best crystallinity and high purity when CaO/SiO₂ was 1.0. Therefore, the samples with CaO/SiO₂ of 1.0 were used in the subsequent experiments. The synthetic C-A-S-H gel with CaO/SiO₂ of 1.0 is an agglomerated irregular flocculent granular structure that is loose and porous. The research on the basic properties of synthetic C-A-S-H gel modified Portland cement shows that the addition of synthetic C-A-S-H gel can significantly shorten the setting time of Portland cement; and the appropriate addition of synthetic C-A-S-H gel can improve，to some extent.，the compressive and flexural strength of Portland cement, when the amount is 1%, the maximum amount of the anti-folding strength is increased, and the increase in the compressive strength is also very good, but when the amount of synthetic C-A-S-H gel is too large, the strength of Portland cement will decline. In addition, the amount of synthetic C-A-S-H gel and curing time have no significant effect on cement hydration products; the addition of synthetic C-A-S-H gel can promote the formation of C-(A)-S-H gel in cement, and synthesize C-A-S-H condensation. The more the rubber is mixed, the more the amount of fibrous substances, the denser the distribution; the addition of synthetic C-A-S-H gel makes the hydration heat release of Portland cement increase, and the acceleration phase advances, which accelerates the hydration process of cement.

Key words: C-A-S-H gel;Portland cement; modified;cement hydration;early performance

目 录

摘 要 I

ABSTRACT III

第一章 绪论 1

1.1研究背景 1

1.2 C-A-S-H类凝胶 3

1.2.1 C-A-S-H凝胶的结构 3

1.2.2 C-A-S-H凝胶的合成 4

1.3 C-A-S-H类凝胶国内外研究现状 5

1.4 存在问题及研究难点 6

1.5 主要内容及研究意义 6

1.5.1 主要内容 6

1.5.2 研究意义 7

第二章 实验过程 9

2.1原材料 9

2.1.1普通硅酸盐水泥 9

2.1.2标准砂 9

2.1.3 nano-SiO₂ 9

2.1.4 nano-Al₂O₃ 9

2.1.5其他原料 9

2.2实验仪器及设备 9

2.3 实验方法 10

2.3.1 C-A-S-H凝胶的合成 10

2.3.2 C-A-S-H凝胶改性普通硅酸盐水泥的制备 11

2.3.3 C-A-S-H凝胶的表征及C-A-S-H凝胶改性普通硅酸盐水泥性能测试 12

第三章 合成C-A-S-H凝胶结构表征 14

3.1 合成C-A-S-H凝胶物相组成研究 14

3.2合成C-A-S-H凝胶微观形貌研究 15

3.3本章小结 15

第四章 C-A-S-H凝胶改性普通硅酸盐水泥基本性能及机理研究 16

4.1合成C-A-S-H凝胶改性普通硅酸盐水泥基本性能 16

4.1.1 合成C-A-S-H凝胶改性普通硅酸盐水泥的凝结时间 16

4.1.2 合成C-A-S-H凝胶改性普通硅酸盐水泥的力学强度 17

4.2 合成C-A-S-H凝胶改性普通硅酸盐水泥机理探究 20

4.2.1合成C-A-S-H凝胶改性普通硅酸盐水泥水化产物物相组成 20

4.2.2合成C-A-S-H凝胶改性普通硅酸盐水泥的微观形貌 21

4.2.3合成C-A-S-H凝胶改性普通硅酸盐水泥的水化放热 23

4.3 本章小结 25

请支付后下载全文，论文总字数：31327字