Influence of Chloride Contamination on the Specific Surface Area of Loess

Chen, Wen Wu; Xu, Yan Rong; Guo, Zhi Qian

doi:10.4028/www.scientific.net/amr.838-841.894

Cited by 4 publications

(3 citation statements)

References 13 publications

(12 reference statements)

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“…The CT image is a 16-bit grayscale image with 65,536 color values. Comparing the segmented sample pores with the undisturbed loess pores, 11,280 was obtained as the best segmentation threshold point 41 . Using Avizo software, the micron-scale CT 3D structure data of the undisturbed loess, including diameter, area, angle, and sphericity of the pores and particles, were calculated using median filtering, noise reduction, and threshold segmentation.…”

Section: Sampling and Methodsmentioning

confidence: 99%

“…Equivalent diameter is the average length of the diameters measured at 2-degree intervals and was passed through the center of the object and calculated as 26 : where, d i is the equivalent diameter, and J is the number of particles and pores. When the roughness of the object or its pore size is reduced, its specific surface area (SSA) also increases 41 . The specific surface area is the surface area per unit volume and can be calculated as: where, A 3Dpore is the pore area, and V 3Dpore is the pore volume.…”

Section: Sampling and Methodsmentioning

confidence: 99%

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The structural evolution of undisturbed loess due to water infiltration

Zhuang,

Kong,

Zhu

et al. 2024

Sci Rep

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Loess structure is the physical key factor that determines its stability and consists of macro-pores, loose texture, and water sensitivity. The structural change characteristics and effects of the undisturbed loess before and after water infiltration are studied using mechanical CT and simulation tests in order to study the structural change process within the undisturbed loess caused by water infiltration. The change in particle state is as follows: the peak frequency point of the equivalent diameter of the loess particles after infiltration ranged from 16.75 to 23.76 μm, and the eroded fine particles consisted primarily of fine particles. The smaller loess particles are removed by water infiltration resulting in coarsening of soil particles. The sphericity of the loess particles gradually changes from spherical pores to angular and dendritic pores. The particle inclination angle transitions to a range greater than 70°, and its proportion is approximately 61%. The change in pore structure is as follows: The loess porosity after infiltration increased by approximately 20%, and the increase in the pore area ratio of the mesopores and the macropores was higher than that of the micropores. Additionally, the small pores increased by more than 5 times the original state of the undisturbed loess. The connected pores expanded less than 60% of the initial state to more than 90% after infiltration, thus, increasing the dominant seepage channel of the undisturbed loess. These changes in particle and porosity further increase the water filtration intensity and promote the migration of fine particles (mainly silt particles), linking loess catastrophes and are the leading cause of loess settlement and slope instability. The process of water infiltration into the loess, the mechanism of loess collapsibility, and the influence of salinity on the loess structure and strength are discussed in this study.

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Section: Sampling and Methodsmentioning

confidence: 99%

Section: Sampling and Methodsmentioning

confidence: 99%

The structural evolution of undisturbed loess due to water infiltration

Zhuang,

Kong,

Zhu

et al. 2024

Sci Rep

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“…Since the 1960s, studies on the microstructure of loess have changed from the initial qualitative analysis approach to the current quantitative analysis. These quantitative analyses mainly contain different calculated or statistical parameters based on the many methods of characterizing loess and have included the use of microscopes, electron microscopes, computer tomography (CT) scanners, mercury intrusion porosimetry (MIP), Brunauer Emmett Teller measurement (BET) and scanning electron microscopy (SEM) [6][7][8][9] . Among these characterization techniques, SEM has become one of the most common tools in researching the microstructure of loess.…”

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confidence: 99%

Comparison and quantitative analysis of microstructure parameters between original loess and remoulded loess under different wetting-drying cycles

Yuan

Lü

et al. 2020

Sci Rep

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The microstructural evolution of loess had a significant impact on the collapsibility of loess during wetting-drying cycles. Based on the analysis of scanning electron microscope (SEM) images by using Image-Pro Plus, the present study quantitatively compared the microstructural parameters of original loess and remoulded loess with different moisture content before and after wetting-drying cycles in size, shape, and arrangement. In size, the average diameter of both original loess particles and remoulded loess particles increased with the increasing of initial moisture content. However, the average diameter of original loess particles was slightly larger than that of remoulded loess particles before wetting-drying cycles. In contrast, the average diameter of both original loess particles and remoulded loess particles were very close to each other after three wetting-drying cycles. In shape, before wetting-drying cycles, the average shape factor of original loess particles was higher than that of remoulded loess particles. After three wetting-drying cycles, the difference in the average shape factor of both two loess samples with 5% initial moisture content is similar to that before wettingdrying cycles. Nevertheless, the average shape factor of both original loess particles and remouled loess particles with 15% initial moisture content were very close to that with 25% initial moisture content. in the arrangement, directional frequency indicated remoulded loess appeared to be more vertically aligned than original before and after three wetting-drying cycles. Furthermore, the directed anisotropy rate of remoulded loess was higher than that of the original loess before and after three wetting-drying cycles. In summary, the size, shape, and arrangement of both original loess particles and remoulded loess particles varied in different degrees before and after three wetting-drying cycles. Combined with the water retention curve of the loess, we analyzed the microstructural evolution mechanism of two loess particles during wetting-drying cycles. It is an excellent significance to study the engineering properties of original loess and remoulded loess. As widespread continental sediment, loess covers about 10% of the total land area of the world. At the same time, China exhibits the most extensive distribution in the loess region of the world, especially for Chinese loess plateau, with a total area of about 640,000 km 2. In China, loess deposits account for more than 6% of the territory and are mainly distributed in the regions of Shanxi, Shaanxi, Gansu, and Ningxia 1. Shallow loess (Q 3 loess) in the Loess Plateau over northwestern china is typical aeolian loess, which is mainly composed of coarse powders, including a fraction of clay minerals, soluble salts, and CaCO 3. Therefore, loess soil has a metastable structure with aggregates and bracket macropores 2,3. The main engineering-geological problem of this loess is significantly reduced strength and large collapsing deformation under wet stress path and external load.

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