混凝土界面过渡区和冻融耐久性纳米划痕表征研究

发布时间：2018-05-25 23:59

本文选题：混凝土 + 界面过渡区　；参考：《上海交通大学》2015年硕士论文

【摘要】：混凝土材料作为当今世界应用最广泛的工程材料之一,它的强度性能、耐久性能都受到工程师和科研工作者的极大关注。作为一种各向异性的多孔复合材料,混凝土的微观结构对其宏观性能有着重要的影响。本文对常规水灰比配比的混凝土样品骨料-水泥微观结构及其界面过渡区进行表征,分析微观结构组成和界面力学性能,研究冻融循环下微观结构变化,探讨纳米划痕试验方法在混凝土界面力学研究的应用,为研究混凝土微观力学性能提供新的方法,从而给宏观结构设计分析提供参考。基于纳米划痕试验方法,结合扫描电子显微镜和扫描探针技术,本文对于混凝土样品微观情况下的骨料-水泥界面进行了表征分析,利用统计学方法对表征结果进行处理,得到基于界面位置变化的微观结构划痕硬度高斯混合模型分布情况。定义了骨料和水泥浆之间的界面过渡区,并进一步对冻融循环作用下的界面过渡区性能进行了表征研究。研究发现,界面过渡区孔隙率较高,微裂纹较多,划痕硬度约为水泥浆体硬度的75%左右,过渡区厚度约为25~40μm。在冻融循环作用下,水泥浆体尤其是界面过渡区在三相结构中受损最为严重,导致微观结构力学性能退化,1500次冻融作用下划痕硬度减少将近40%。研究表明,界面过渡区虽然占比较小,但是是混凝土三相结构中最为脆弱的部分,冻融循环作用对微观结构尤其是水泥浆体和界面过渡区的劣化作用是混凝土整体结构耐久性退化的重要影响因素。微观界面过渡区力学性能对混凝土结构整体性能有着非常的影响。
[Abstract]:As one of the most widely used engineering materials in the world, the strength and durability of concrete materials are paid great attention by engineers and researchers. As an anisotropic porous composite, the microstructure of concrete has an important effect on its macroscopic properties. In this paper, the microstructure of aggregate cement and its interfacial transition zone are characterized, the microstructure and mechanical properties of interface are analyzed, and the microstructure changes under freeze-thaw cycle are studied. This paper discusses the application of nano-scratch test method in the study of concrete interface mechanics, which provides a new method for studying the microscopic mechanical properties of concrete and provides a reference for the design and analysis of macroscopic structure. Based on nano-scratch test method and scanning electron microscope (SEM) and scanning probe technique, the aggregate cement interface of concrete samples was characterized and analyzed in this paper, and the characterization results were processed by statistical method. The distribution of Gao Si mixed model of microstructural scratch hardness based on the change of interface position is obtained. The interfacial transition zone between aggregate and cement slurry is defined, and the properties of interface transition zone under freeze-thaw cycle are studied. It is found that the interfacial transition zone has higher porosity and more microcracks. The scratch hardness is about 75% of the cement paste hardness, and the thickness of the transition zone is about 2540 渭 m. Under the action of freeze-thaw cycle, the cement paste, especially the interfacial transition zone, is most seriously damaged in the three-phase structure, resulting in the degradation of the mechanical properties of the microstructure and the reduction of scratch hardness by nearly 40% under 1500 times of freezing and thawing. The results show that although the interfacial transition zone is relatively small, it is the most vulnerable part of the three-phase concrete structure. The deterioration of microstructure, especially cement paste and interfacial transition zone due to freeze-thaw cycle is an important factor affecting the durability degradation of the whole concrete structure. The mechanical properties of the micro-interface transition zone have a great influence on the overall performance of concrete structure.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

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