|Table of Contents|

Analysis on microscopic mechanism of sulfate saline soil improved by inorganic materials(PDF)

《建筑科学与工程学报》[ISSN:1673-2049/CN:61-1442/TU]

Issue:
2023年02期
Page:
129-137
Research Field:
岩土工程
Publishing date:

Info

Title:
Analysis on microscopic mechanism of sulfate saline soil improved by inorganic materials
Author(s):
YANG Xiaohua1;  WANG Lixin1;  ZHANG Shasha1;  XIE Shanjie2
(1. School of Highway, Chang'an University, Xi'an 710064, Shaanxi, China; 2. China Railway Siyuan Survey and Design Group Co., Ltd., Wuhan 430063, Hubei, China)
Keywords:
saline soil;  inorganic material improvement;  microscopic mechanism;  X-ray diffraction;  scanning electron microscope
PACS:
TU973.2
DOI:
10.19815/j.jace.2021.09121
Abstract:
In order to deeply explore the microscopic mechanism of sulfated saline soil improved by inorganic materials, three inorganic materials with different ratios of lime, lime + fly ash, and lime+volcanic ash were used for the improvement of sulfate saline soil with a soluble salt content of 1.61%. Through chemical composition analysis test, X-ray diffraction test and scanning electron microscope test, the chemical and mineral composition changes before and after the improvement were studied, and the microscopic mechanism and microstructure of the inorganic material to improve the sulfate saline soil were analyzed. The results show that sulphate ion content significantly decreases after adding the improved materials. The lime modified soil decreases by 41.37%, the lime+fly ash modified soil decreases by 44.64%, and the lime + volcanic ash modified soil decreases by 59.75%, which effectively reduces the formation of glauber's salt. In terms of salt content and sulfate ion content, the lime+volcanic ash modifier has the best improvement effect. The most obvious element in the soil before and after the improvement is calcium. The calcium in the lime-improved soil increases by 73.28%, lime+fly ash modified soil increases by 30.17%, and the lime+volcanic ash modified soil increases by 27.59%. One part of the calcium element exists in the form of calcium carbonate, and the other part exists in the form of calcium sulfate and other minerals. The diffraction intensity of quartz, calcite and calcium carbonate is enhanced, the low amorphous phases increase, and the mineral composition in the saline soil is more complex. Needle-like structures are formed in the soil at the beginning of the improvement, indicating that the sulfate in the soil has reacted with the improved material. As time goes by, the needles gradually disappear, the sulfate ion content is further reduced, and the overall strength of the soil is further strengthened. The apparent porosity of the saline soil after 28 d improvement is greatly reduced. The lime-improved soil decreases by 53.19%, lime+fly ash modified soil decreases by 54.33%, and lime+volcanic ash modified soil decreases by 51.14%. Large pores in the soil decreases, small pores increases, and the pore size becomes relatively uniform. For the coarse-grained sulfate saline soil before and after improvement, the structure of the soil remains unchanged, and is dominated by a single-grain structure, while the arrangement of the soil particles before the improvement of the fine-grained sulphate saline soil is difficult to identify, and the soil particles after the improvement are mainly stacked in surface-to-surface contact.

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Last Update: 2023-03-20