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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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Autores principales: Shang, Yunzhi, Cui, Zhenglong, Li, Yongjing, Zhang, Yannian, Cheng, Yaohui
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10650268/
https://www.ncbi.nlm.nih.gov/pubmed/37959553
http://dx.doi.org/10.3390/ma16216957
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author Shang, Yunzhi
Cui, Zhenglong
Li, Yongjing
Zhang, Yannian
Cheng, Yaohui
author_facet Shang, Yunzhi
Cui, Zhenglong
Li, Yongjing
Zhang, Yannian
Cheng, Yaohui
author_sort Shang, Yunzhi
collection PubMed
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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spelling pubmed-106502682023-10-30 Strength and Microscopic Mechanism of Cement–Fly Ash–Slag–Desulfurization Gypsum Solidified Mica Schist Weathered Soil Shang, Yunzhi Cui, Zhenglong Li, Yongjing Zhang, Yannian Cheng, Yaohui Materials (Basel) Article 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. MDPI 2023-10-30 /pmc/articles/PMC10650268/ /pubmed/37959553 http://dx.doi.org/10.3390/ma16216957 Text en © 2023 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Shang, Yunzhi
Cui, Zhenglong
Li, Yongjing
Zhang, Yannian
Cheng, Yaohui
Strength and Microscopic Mechanism of Cement–Fly Ash–Slag–Desulfurization Gypsum Solidified Mica Schist Weathered Soil
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 Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10650268/
https://www.ncbi.nlm.nih.gov/pubmed/37959553
http://dx.doi.org/10.3390/ma16216957
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