纳米压痕技术研究水泥基材料基本性能

发布时间：2018-05-09 22:26

本文选题：水泥基材料 + 纳米压痕　；参考：《交通部公路科学研究院》2014年硕士论文

【摘要】：随着科技的进步和经济的发展，水泥基材料的性能不断提高，应用范围日益广泛。水泥基材料的宏观性质迥异，究其本质是由微观尺度上的材料特性决定的。为进一步满足实际工程需求，必须从材料的本质出发进行性能的研究，以获得预测和改善其宏观性能的重要信息。本文使用纳米压痕、热重分析、原子力显微镜成像等先进技术，尤其基于纳米压痕技术作为目前唯一能够定量表征材料微观力学性能这一优势，通过针对性的表面处理程序和合适的加卸载制度，采用15×15的压痕点阵对不同配比的硬化后水泥净浆试件进行测试，基于EM算法对得到的代表水化产物的大样本数据进行高斯混合分布的物相划分并获得各相力学性能，运用微观力学方法计算C-S-H凝胶基本组成单元(凝胶颗粒)的力学性能和堆积密度，探讨堆积方式，建立三相水泥浆体骨架模型分析压痕结果，推算材料水化程度。结果表明水泥基材料中的主要水化产物由LD C-S-H、HD C-S-H和HD/CH复合体三部分组成，不同配合比导致各相水化产物体积百分率有所差异，但同相水化产物的力学性能比较稳定，较低的水胶比有利于生成密实的水化产物，而随着水胶比的增大，低密度的水化产物增多，含矿渣的试件中HD/CH复合体较少。凝胶颗粒基本力学性质较为稳定，说明凝胶颗粒是C-S-H凝胶的基本组成单元，其不同的堆积密度形成了不同的C-S-H相及其相应的力学性能。建立水泥浆体骨架模型计算水泥基材料的水化程度，有助于识别模量处于水化产物和未水化颗粒之间的混合物相的压痕试验数据，并与使用热重分析得到的水化程度进行比较，二者吻合较好。因此，纳米压痕技术作为微观尺度研究物质的一种手段，可以得到水泥基材料微观结构的综合信息。基于微观尺度材料性质参数，可以与更大尺度进行逐级联系，，以期系统掌握水泥基材料的本质特征，有针对性地改善材料宏观性能。
[Abstract]:With the progress of science and technology and the development of economy, the properties of cement-based materials have been improved and the application range is more and more extensive. The macroscopical properties of cement-based materials are very different, and their essence is determined by the micro-scale material properties. In order to meet the needs of practical engineering, it is necessary to study the properties from the point of view of the nature of materials, in order to obtain important information to predict and improve their macroscopic properties. In this paper, nanoindentation, thermogravimetric analysis, atomic force microscope imaging and other advanced techniques are used, especially based on nano-indentation technology as the only quantitative characterization of the material's micromechanical properties. Through the specific surface treatment program and the suitable loading and unloading system, the indentation lattice of 15 脳 15 was used to test the hardened cement paste specimen with different ratio. Based on EM algorithm, the obtained large sample data representing hydration products are partitioned by Gao Si mixed distribution, and the mechanical properties of each phase are obtained. The mechanical properties and packing density of the basic component unit (gel particle) of C-S-H gel were calculated by means of micromechanics method. The packing mode was discussed, and the indentation result was analyzed by using the framework model of three-phase cement paste, and the hydration degree of the material was calculated. The results show that the main hydration products in cement-based materials are composed of LD C-S-HNH HD C-S-H and HD/CH complexes. The volume percentage of hydration products varies with different mixing ratios, but the mechanical properties of the hydration products in the same phase are relatively stable. The low water-binder ratio is favorable to the formation of dense hydration products, but with the increase of water-binder ratio, the low-density hydration products increase, and the HD/CH complex is less in the samples containing slag. The basic mechanical properties of the gel particles are relatively stable, which indicates that the gel particles are the basic components of the C-S-H gel. The different packing densities of the gel particles form different C-S-H phases and their corresponding mechanical properties. Establishing a cement paste skeleton model to calculate the hydration degree of cement-based materials is helpful to identify the indentation test data of mixtures whose modulus is between hydrated products and unhydrated particles, and to compare with the hydration degree obtained by thermogravimetric analysis. The two agree well. Therefore, nanoindentation technology can be used as a means to study materials on a micro scale, and comprehensive information of microstructure of cement based materials can be obtained. Based on the properties of micro-scale materials, they can be connected with the larger scale step by step, in order to systematically grasp the essential characteristics of cement-based materials and improve the macroscopic properties of the materials.
【学位授予单位】：交通部公路科学研究院
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U414

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