纳米材料对水泥净浆体系的影响及作用机理研究

发布时间：2018-01-14 01:05

本文关键词：纳米材料对水泥净浆体系的影响及作用机理研究　出处：《沈阳大学》2017年硕士论文　论文类型：学位论文

【摘要】：本研究重点对纳米SiO_2和纳米CaCO_3在水泥净浆中发挥的作用以及作用机理进行分析。在水泥中掺加纳米材料可以显著提高水泥净浆各种性能,但同时也会带来一些不良的影响。通过一些列实验结合电镜扫描等手段对掺入纳米材料后水泥净浆的工作性能、力学性能、干所性能、电阻率变化等进行了分析研究。本研究在相同配合比的前提下,在水泥净浆中掺入不同种类和不同剂量的纳米材料后对其流动性进行了测试,经试验后发现纳米材料的添加会使水泥浆的流动性出现降低的情况。其中掺入纳米SiO_2后水泥净浆的流动性下降最为明显,为掺入纳米CaCO_3后水泥净浆的流动性变化不大,流动性曲线比较平缓。在水泥净浆的力学性能试验中发现,将1.0%的纳米SiO_2(关于水泥质量百分比)添加试件中,试件抗压、抗折强度会出现较大幅度上涨的情况;在添加纳米CaCO_3的量为1.5%时,试件的抗折、抗压强度也出现了大幅度上升的状况。因为纳米材料通过填充试件微小孔洞的方式改善了试件的微观结构从而使其微观结构更加完整和密实,因而抗压及抗折强度出现了上升的情况。从水泥净浆的干燥收缩实验中可以发现,掺入纳米材料后试件的干缩率相对于未掺入纳米材料的普通试件来说,会产生不同程度的增长。其中掺入1.0%纳米SiO_2和掺入1.5%纳米CaCO_3后的试件干缩率最大。掺入纳米材料后,水泥净浆试件内部的湿度会降低,同时会增加试件内部弯月面的数量,从而使得试件的干缩率出现上升。从试件的电阻率变化情况中可以发现掺加纳米材料后试件的电阻率明显要高于普通的试件,且水化的各个阶段都得到了提前。这是因为掺入纳米材料后水泥净浆内部的微小孔洞的得到了填补,同时内部湿度也得到了降低,因此使得掺入纳米材料后的水泥净浆电阻率升高。此外,纳米材料的表面能非常高,能够加快水泥水化反应,从而使得水化的各个阶段提前到来。使用电子显微镜(SEM)等技术对试件的微观结构进行分析。由于纳米材料数量级非常小,因此可以有效的填补试件内部的一些孔洞及缺陷。通过对试件的微观结构进行观察发现,掺入纳米材料的试件相对于普通试件来说,其密实程度得到了很大程度的提高。
[Abstract]:The role and mechanism of nano SiO_2 and nano CaCO_3 in cement paste are analyzed. The addition of nano material into cement can significantly improve the properties of cement paste. But at the same time it will also bring some adverse effects. Through some series of experiments combined with scanning electron microscope and other means of cement paste after doped with nano-materials the working properties mechanical properties and dry properties. On the premise of the same mix ratio, the fluidity of the cement paste was tested by adding different kinds of nano-materials and different dosages of nano-materials. It is found that the fluidity of cement slurry decreases with the addition of nano-materials, and the fluidity of cement paste decreases most obviously with the addition of nanometer SiO_2. The fluidity of cement paste changed little and the fluidity curve of cement paste was relatively smooth after the addition of nanometer CaCO_3. It was found in the test of mechanical properties of cement paste. When 1.0% nano-SiO-2 (about cement mass percentage) is added to the specimen, the compressive strength and the flexural strength of the specimen will increase by a large margin; When the amount of nanometer CaCO_3 is 1.5, the specimen is flexural. The compressive strength also increased greatly, because the nano-material improved the microstructure of the specimen by filling the tiny holes in the specimen and made the microstructure more complete and dense. As a result, the compressive strength and flexural strength increased. From the dry shrinkage experiment of cement paste, it can be found that the dry shrinkage rate of the specimens after the addition of nano-materials is higher than that of the ordinary specimens without nano-materials. Among them, the dry-shrinkage rate of the specimens with 1.0% nm SiO_2 and 1.5% nm CaCO_3 was the highest, and the dry shrinkage rate was the highest with the addition of nanomaterials. The humidity of cement paste specimen will decrease and the number of meniscus will increase. From the change of the resistivity of the specimen, it can be found that the resistivity of the specimen doped with nano-materials is obviously higher than that of the ordinary specimen. And each stage of hydration has been advanced, this is because the incorporation of nanomaterials into the cement paste has been filled in the tiny pores, and the internal humidity has also been reduced. In addition, the surface energy of nano-materials is very high, which can accelerate the hydration reaction of cement. In order to make the hydration stage come ahead of schedule, the microstructure of the samples was analyzed by means of electron microscope (SEM) and so on. The order of magnitude of nanomaterials is very small. Therefore, we can effectively fill some holes and defects in the specimen. Through the observation of the microstructure of the specimen, it is found that the specimen doped with nano-materials is relative to the ordinary specimen. The degree of compactness has been greatly improved.
【学位授予单位】：沈阳大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ172.1;TB383.1

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