Strength and Microscopic Mechanism of Cement–Fly Ash–Slag–Desulfurization Gypsum Solidified Mica Schist Weathered Soil
Mica schist weathered soil possesses a number of poor engineering characteristics, which make it difficult to use as a subgrade material for resource utilization. Therefore, in this study, a new type of curing agent, CFSD (cement–fly ash–slag–desulfurized gypsum), is proposed for this soil. The effe...
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MDPI AG
2023-10-01
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| author | Yunzhi Shang Zhenglong Cui Yongjing Li Yannian Zhang Yaohui Cheng |
| author_facet | Yunzhi Shang Zhenglong Cui Yongjing Li Yannian Zhang Yaohui Cheng |
| author_sort | Yunzhi Shang |
| collection | DOAJ |
| description | Mica schist weathered soil possesses a number of poor engineering characteristics, which make it difficult to use as a subgrade material for resource utilization. Therefore, in this study, a new type of curing agent, CFSD (cement–fly ash–slag–desulfurized gypsum), is proposed for this soil. The effects of different curing agent dosages, age of preservation, and confining pressure on the stress–strain curves were analyzed via the uniaxial compression test and triaxial compression test, while the micromorphological characteristics of cured soil were analyzed via X-ray diffraction analysis and the SEM test combined with Image J software. In this paper, we also establish a microscopic mechanism model to determine how curing agents increase the strength of mica schists. The results reveal that the compressive strength of solidified soil increases rapidly within 28 days; the CFSD dosage of 4% at 7 d increased by 103.23% by 28 d. After 28 d, the trend of compressive strength growth was flat. The CFSD dosage of 4% at 7 d increased by 128.34% by 90 d; with the increase in the dosage, the curve transformed from flat to steep. These results suggest that the CFSD dosage is positively correlated with the damage strain and damage bias stress of solidified soil. The curves for the strain softening type with a 4% dosage as the initial effective confining pressure increased from 50 kPa to 300 kPa; the failure stress and failure strain increased by 202.09% and 90.85%, respectively. With the increase in curing agent dosage and maintenance age, the pore size of 2~5 μm, >5 μm interval decreased from 56.46% to 27.92%, the porosity decreased from 12.51% to 4.6%, and the hydrate produced by the curing agent cemented and filled up the pore space between the loose particles of the soil body. Thus, the large pore space became microporous, and the pore structure densification was greatly improved. |
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| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-11T11:26:11Z |
| publishDate | 2023-10-01 |
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| series | Materials |
| spelling | doaj.art-4ade1f63267c4628805d56b5193940722023-11-10T15:07:27ZengMDPI AGMaterials1996-19442023-10-011621695710.3390/ma16216957Strength and Microscopic Mechanism of Cement–Fly Ash–Slag–Desulfurization Gypsum Solidified Mica Schist Weathered SoilYunzhi Shang0Zhenglong Cui1Yongjing Li2Yannian Zhang3Yaohui Cheng4School of Civil Engineering, Liaoning Technical University, Fuxin 123000, ChinaSchool of Civil Engineering, Liaoning Technical University, Fuxin 123000, ChinaSchool of Civil Engineering, Liaoning Technical University, Fuxin 123000, ChinaSchool of Civil Engineering, Shenyang Jianzhu University, Shenyang 110168, ChinaSchool of Civil Engineering, Liaoning Technical University, Fuxin 123000, ChinaMica schist weathered soil possesses a number of poor engineering characteristics, which make it difficult to use as a subgrade material for resource utilization. Therefore, in this study, a new type of curing agent, CFSD (cement–fly ash–slag–desulfurized gypsum), is proposed for this soil. The effects of different curing agent dosages, age of preservation, and confining pressure on the stress–strain curves were analyzed via the uniaxial compression test and triaxial compression test, while the micromorphological characteristics of cured soil were analyzed via X-ray diffraction analysis and the SEM test combined with Image J software. In this paper, we also establish a microscopic mechanism model to determine how curing agents increase the strength of mica schists. The results reveal that the compressive strength of solidified soil increases rapidly within 28 days; the CFSD dosage of 4% at 7 d increased by 103.23% by 28 d. After 28 d, the trend of compressive strength growth was flat. The CFSD dosage of 4% at 7 d increased by 128.34% by 90 d; with the increase in the dosage, the curve transformed from flat to steep. These results suggest that the CFSD dosage is positively correlated with the damage strain and damage bias stress of solidified soil. The curves for the strain softening type with a 4% dosage as the initial effective confining pressure increased from 50 kPa to 300 kPa; the failure stress and failure strain increased by 202.09% and 90.85%, respectively. With the increase in curing agent dosage and maintenance age, the pore size of 2~5 μm, >5 μm interval decreased from 56.46% to 27.92%, the porosity decreased from 12.51% to 4.6%, and the hydrate produced by the curing agent cemented and filled up the pore space between the loose particles of the soil body. Thus, the large pore space became microporous, and the pore structure densification was greatly improved.https://www.mdpi.com/1996-1944/16/21/6957mica schist weathered soilsolid wastestrengthmicroscopic characteristics |
| spellingShingle | Yunzhi Shang Zhenglong Cui Yongjing Li Yannian Zhang Yaohui Cheng Strength and Microscopic Mechanism of Cement–Fly Ash–Slag–Desulfurization Gypsum Solidified Mica Schist Weathered Soil Materials mica schist weathered soil solid waste strength microscopic characteristics |
| title | Strength and Microscopic Mechanism of Cement–Fly Ash–Slag–Desulfurization Gypsum Solidified Mica Schist Weathered Soil |
| title_full | Strength and Microscopic Mechanism of Cement–Fly Ash–Slag–Desulfurization Gypsum Solidified Mica Schist Weathered Soil |
| title_fullStr | Strength and Microscopic Mechanism of Cement–Fly Ash–Slag–Desulfurization Gypsum Solidified Mica Schist Weathered Soil |
| title_full_unstemmed | Strength and Microscopic Mechanism of Cement–Fly Ash–Slag–Desulfurization Gypsum Solidified Mica Schist Weathered Soil |
| title_short | Strength and Microscopic Mechanism of Cement–Fly Ash–Slag–Desulfurization Gypsum Solidified Mica Schist Weathered Soil |
| title_sort | strength and microscopic mechanism of cement fly ash slag desulfurization gypsum solidified mica schist weathered soil |
| topic | mica schist weathered soil solid waste strength microscopic characteristics |
| url | https://www.mdpi.com/1996-1944/16/21/6957 |
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