QUANTITATIVE STUDY ON MICROSTRUCTURE CHARACTERISTICS OF WHITE DIATOMITE
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摘要: 硅藻土常常呈现白色、黄色、黑色等颜色,其中以白色硅藻土较为特殊,遇水后其强度明显降低。为了掌握白色硅藻土的工程特性,必须研究白色硅藻土的微观结构特征。本文以白色硅藻土为研究对象,通过扫描电镜试验,以数值化的形式展现其孔隙特征,从微观角度分析白色硅藻土的整体形貌,同时对白色硅藻土的微观结构进行量化分析,通过二值化处理以及分形维数分析,对白色硅藻土土体孔隙的微观特征进行研究,结果表明:(1)白色硅藻土具有独特的无序排列的多孔结构,颗粒群间的聚集主要以堆积聚合排列的形式存在,其整体结构主要表现为分散结构,接触形式以面对面为主。(2)白色硅藻土微观费雷特直径分布结果表明其微观孔隙普遍较小,且孔径值大小呈现出无规律分布情况,随机性较强;孔隙结构处于不规则形状,呈现出细小孔隙形态。(3)白色硅藻土拥有较高的面孔隙度,在微观上表现为孔隙小、数量繁多以及结构复杂。(4)白色硅藻土具有较好的分形特性,在不同阈值下硅藻土的分形维数呈现出非线性减小的趋势,且阈值越大,分形维数降低的幅度越大;同时白色硅藻土的分形维数值较大,表明白色硅藻土微观表面孔隙结构单元数量较多,在宏观上表现出孔隙小,孔隙数量较多的特征。Abstract: Diatomite often appears white, yellow, black or other colors. The white diatomite is more special, and its strength decreases significantly when it meets water. In order to accurately grasp the engineering characteristics of white diatomite, it is necessary to master the microstructure of white diatomite. This paper takes the white diatomite as the research object. We use the SEM test and display the pore characteristics of the white diatomite by numerical method. The overall morphology of the white diatomite is analyzed from the microscopic point of view. At the same time, we quantitatively analyzes the microstructure of the white diatomite, and studies the micro characteristics of the pores of the white diatomite through the binarization analysis and fractal dimension analysis. The results show the following findings. (1)The white diatomite has a unique disordered porous structure. The aggregation of particles is mainly in the form of accumulation polymerization. Its overall structure is mainly in the form of dispersion structure. The contact form is mainly face-to-face. (2)The micro pore size of white diatomite is generally small. The pore size presents an irregular distribution with strong randomness. The pore structure has irregular shape, showing a small pore shape. (3)White diatomite has relatively high surface porosity. It is manifested as small pore size, large quantity and complex structure on the microscopic level. (4)White diatomite has good fractal characteristics. The fractal dimension of diatomite shows a nonlinear decreasing trend under different thresholds. The larger the threshold is, the larger the fractal dimension decreases. At the same time, the fractal dimension value of white diatomite is large. This result indicates that there are more pore structure units on the micro surface of white diatomite, which shows the characteristics of small pores and large number of pores on the macro level.
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表 1 白色硅藻土基本物理特性
Table 1. Basic physical properties of white diatomite
含水率ω/% 密度ρ/g·cm-3 比重Gs 液限ωL/% 塑限ωP/% 液性指数IL 塑性指数IP 40.7 1.82 2.47 94.91 36.69 0.07 59 表 2 白色硅藻土面孔隙度计算结果
Table 2. Calculation results of surface porosity of white diatomite
计算内容 试样1 试样2 试样3 孔隙部分/像素点 6589 9195 10 313 土骨架部分/像素点 5798 8452 9493 面孔隙度/% 53.19 52.11 52.07 表 3 白色硅藻土试样的分形维数
Table 3. Fractal dimension of white diatomite samples
名称 分形维数 试样1 1.92 试样2 1.91 试样3 1.90 -
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