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毕业论文网 > 毕业论文 > 材料类 > 无机非金属材料工程 > 正文

碳酸钙质材料对水泥基材料钢筋锈蚀的影响毕业论文

 2020-04-18 19:59:03  

摘 要

本课题主要研究碳酸钙质材料-水泥体系的水化和强度,以及模拟孔溶液条件下,钢筋的电化学行为。采用的碳酸钙质材料为石灰石粉和珊瑚砂粉,两种水泥体系:普通硅酸盐水泥和硫铝酸盐水泥。石灰石粉和珊瑚砂粉掺量依次为0%、5%、15%、25%,水灰比为0.5。实验中将制成的样品放在20℃养护箱中密封养护,在7 d、28 d时取出,并进行终止水化,磨粉后进行X射线衍射分析(XRD),模拟硅酸盐水泥孔溶液,掺入一定的氯盐,进行普通钢筋电化学实验。

试验结果表明,在硅酸盐水泥体系中,珊瑚砂粉的掺入,会生成单碳铝酸钙(Mc)和半碳铝酸钙(Hc),且会促进AFt的生成,并且随着珊瑚砂粉掺入量的增加,Mc和Hc的特征峰高度也有所提高,这与石灰石粉的掺入对硅酸盐水泥体系的影响一致。而在硫铝酸盐水泥体系中,珊瑚砂粉的掺入,只会生成Hc,并未发现Mc的生成,也与石灰石粉在硫铝酸盐水泥中的掺入影响一致。

珊瑚砂粉和石灰石粉的掺入降低了普通硅酸盐水泥的砂浆强度,随着掺量的增加,强度下降越多,具体表现在:7 d强度明显降低;28 d时,水泥砂浆的强度并未大幅度下降,但当珊瑚砂掺入量达到25%时,水泥强度下降了25%。

通过CHI电化学工作站等仪器对钢筋在模拟孔溶液中的电化学行为进行表征。可以看出,Nyquist图中的高频区半径变小,意味着随着石灰石/珊瑚砂粉掺入,会使离子迁移阻力降低,腐蚀电流变大;同时,短期内,掺杂石灰石/珊瑚砂粉的模拟孔溶液会加快电化学反应,加快钢筋的锈蚀,而随着时间的增长,钢筋表面开始生成钝化膜,电流密度逐渐降低。说明随着时间的进行,是否掺杂碳酸钙质材料对钢筋在孔溶液中的电化学反应影响较小。

关键词:石灰石粉;珊瑚砂粉;孔溶液;电化学锈蚀;强度

Abstract

In this paper, the hydration and strength of calcium carbonate material-cement system and the electrochemical behavior of steel bar in simulated pore solution were studied. Calcareous carbonate materials are calcareous powder and coral sand powder, two kinds of cement systems: ordinary Portland cement and sulphoaluminate cement. The content of calcareous powder and coral sand powder was 0%, 5%, 15% and 25%, respectively, and the ratio of water to ash was 0.5. 5%. In the experiment, the samples were sealed and cured in a 20 ℃ curing box, taken out at 7 days and 28 days, and terminated hydration. After grinding, (XRD), was used to form cement mortar at the same time. The silicate cement hydration solution is simulated to carry out the general steel bar electrochemical experiment.

The experimental results show that in Portland cement system, the addition of coral sand powder will produce calcium monocarbamate (Mc) and semi-calcium aluminate (Hc), and promote the formation of AFt, and with the increase of coral sand powder content, The characteristic peak heights of Mc and Hc are also increased, which is consistent with the effect of lime powder on Portland cement system. However, in sulphoaluminate cement system, the addition of coral sand powder only produces Hc, and does not find the formation of Mc, which is consistent with the effect of calcareous powder on sulphoaluminate cement.

The addition of coral sand powder and calcareous powder reduced the mortar strength of ordinary Portland cement. With the increase of the content, the strength decreased more, which showed that the strength decreased obviously in 7 days. At 28 d, the strength of cement mortar did not decrease greatly, but when the amount of coral sand reached 25%, the strength of cement decreased by 25%.

The electrochemical behavior of steel bar in simulated pore solution was characterized by CHI electrochemical workstation and other instruments. It can be seen that the radius of high frequency region in Nyquist diagram becomes smaller, which means that with the addition of limestone / coral sand powder, the ion migration resistance will be reduced and the corrosion current will become larger. At the same time, in a short period of time, the simulated pore solution mixed with limestone / coral sand powder will accelerate the electrochemical reaction and accelerate the corrosion of steel bar. With the increase of time, the passivation film begins to form on the surface of steel bar, and the current density decreases gradually. It is shown that the effect of calcium carbonate on the electrochemical reaction of steel bar in pore solution is more obvious with the development of time. Small.

Key words: Limestone powder, Coral sand powder, Pore solution, Electrochemical corrosion, Strength

目录

摘要 1

Abstract 2

第一章 绪论 5

1.1引言 5

1.2水泥主要矿物组成 6

1.3石灰石粉的掺入对水泥混凝土的影响机理 6

1.4珊瑚砂的掺入对水泥混凝土的影响机理 8

1.5氯盐侵蚀钢筋混凝土的机理[12] 8

1.6研究内容 9

第二章 实验材料及实验方法 10

2.1实验用原料 10

2.2实验用测试方法及仪器 11

2.2.1砂浆强度测定方法及仪器 11

2.2.2 X-ray diffraction分析步骤及仪器 12

2.2.3模拟孔溶液中[13]的电化学腐蚀 12

第三章 碳酸钙质材料-水泥二元体系的水化 14

3.1实验方案 14

3.2实验成型的样品 14

3.3碳酸钙质材料-硅酸盐水泥体系的水化产物 14

3.4碳酸钙质材料-硫铝酸盐水泥体系的水化产物 18

3.5强度 22

3.5.1实验方案及试样 22

3.5.2实验结果 23

3.6本章小结 26

第四章 碳酸钙制材料对钢筋锈蚀的电化学行为的影响 28

4.1实验方案 28

4.2实验结果 28

4.3实验数据及处理 29

4.3.1模拟孔溶液中养护1 d 29

4.3.2模拟孔溶液中浸泡3 d 32

5.3.2模拟孔溶液中浸泡7 d 35

4.3.4腐蚀电流密度 38

第五章 结论与展望 40

5.1 结论 40

5.2 展望 40

参考文献 41

致谢 43

第一章 绪论

1.1引言

水泥作为我国最常用的建筑胶凝材料,产量一直位居世界前列。2018年我国水泥产量为21.8亿吨(如图1.1所示),2016年至2018年三年总的水泥产量约为69亿吨,占据世界水泥产量的一半以上。然而近几年,我国水泥产量有所减少,一部分原因是水泥生产会产生大量污染,基于环保要求,我国水泥生产设施建设减少;除此之外,另一部分原因是水泥掺合料的大量使用,如石灰石,矿渣,粉煤灰等。

图1.1 1997-2018年中国水泥产量

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