石墨烯改性水泥材料的制备及其机理研究

发布时间：2018-10-11 09:03

【摘要】：水泥混凝土作为世界上使用最广泛的建筑工程材料,研究其性能改善具有十分重要的现实意义。随着纳米科技的发展,很多研究者将纳米材料引入到水泥中来改善水泥的诸多性能,且取得了可观的效果。石墨烯作为新型的二维纳米材料,由于其优异的性能而受到人们的广泛关注。本文研究了石墨烯和氧化石墨烯对水泥水化历程及水化程度的影响,在此基础上分析了氧化石墨烯在水泥碱性环境中的絮凝现象,同时试图通过球磨法将石墨烯分散在水泥基体中,从而制备出具有良好性能的改性水泥材料。首先采用改性Hummers法制备氧化石墨烯分散液,氧化石墨烯表面呈现褶皱状且含有大量的-OH、-O-和-COOH官能团。借助水化热、TG-DSC等分析方法,研究了石墨烯/氧化石墨烯对水泥水化历程及水化程度的影响:石墨烯/氧化石墨烯的加入对水泥的水化放热速率及总放热量基本没有影响,且氢氧化钙(CH)和化学结合水的含量也没有显著变化。结合SEM分析,可以得出:石墨烯/氧化石墨烯只是物理性的分散在水泥中。对氧化石墨烯在水泥浆体中的絮凝现象进行了研究,采用CH溶液模拟水泥水化后的碱性环境,通过紫外分光光度计和ζ-电位等方法,系统分析了氧化石墨烯发生絮凝现象的过程及解决办法。结果表明:少量的CH(30 mg/L)即可导致氧化石墨烯的絮凝现象,聚羧酸减水剂(PC)能够有效抑制氧化石墨烯的絮凝过程,且氧化石墨烯与PC之间没有化学键的作用。从官能团的角度探究了PC分散氧化石墨烯的机理:相比于-OH,-COOH官能团能有效抑制氧化石墨烯的絮凝过程,同时PC特殊的分子结构对分散氧化石墨烯也有一定的空间位阻作用。通过球磨法将石墨烯均匀分散在水泥中,研究了石墨烯对水泥材料的增强效果。实验结果表明:石墨烯的加入提高了水泥净浆的抗压强度,其最佳掺量为0.03 wt%,此时的强度增长率在9%左右。石墨烯在球磨后其形态基本没有变化,且石墨烯的加入没有诱导水泥矿物生成新的水化产物。
[Abstract]:Cement concrete is the most widely used building material in the world. It is of great practical significance to study its performance improvement. With the development of nanotechnology, many researchers have introduced nanomaterials into cement to improve many properties of cement, and achieved considerable results. Graphene, as a new two-dimensional nanometer material, has been paid more and more attention because of its excellent properties. In this paper, the effects of graphene and graphene oxide on the hydration process and hydration degree of cement were studied, and the flocculation of graphene oxide in alkaline cement environment was analyzed. At the same time, the graphene was dispersed in the cement matrix by ball milling method, so that the modified cement material with good properties was prepared. Firstly, graphene oxide dispersions were prepared by modified Hummers method. Graphene oxide surfaces were ruffled and contained a large number of-OH,-O- and-COOH functional groups. The effects of graphene / graphene oxide on the hydration process and the degree of hydration of cement were studied by means of hydration heat, TG-DSC and other analytical methods: the addition of graphene / graphene oxide had little effect on the hydration heat release rate and total heat release of cement. The content of calcium hydroxide (CH) and chemically bound water did not change significantly. Combined with SEM analysis, it can be concluded that graphene / graphene oxide is only physically dispersed in cement. The flocculation of graphene oxide in cement paste was studied. CH solution was used to simulate the alkaline environment of cement hydration, and ultraviolet spectrophotometer and 味-potential were used to study the flocculation of graphene oxide in cement paste. The process and solution of flocculation of graphene oxide are analyzed systematically. The results show that a small amount of CH (30 mg/L) can lead to the flocculation of graphene oxide. The polycarboxylic acid superplasticizer (PC) can effectively inhibit the flocculation process of graphene oxide, and there is no chemical bond between graphene oxide and PC. The mechanism of PC dispersed graphene oxide was studied from the point of view of functional groups. Compared with-OH,-COOH functional group, the flocculation process of graphene oxide can be effectively inhibited by the functional group. At the same time, the special molecular structure of PC also has a certain steric effect on the dispersion of graphene oxide. Graphene was uniformly dispersed in cement by ball milling, and the reinforcing effect of graphene on cement was studied. The experimental results show that the compressive strength of cement paste is increased with the addition of graphene, and the strength growth rate of the cement paste is about 9% when the optimum addition amount is 0.03 wt%,. The morphology of graphene did not change after ball milling, and the addition of graphene did not induce cement minerals to form new hydration products.
【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ172.1

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