Strength characteristics and microstructure of silty sand improved by red mud, lime and fly ash under dry-wet cycle
Red mud is a kind of solid waste, which can be used as engineering roadbed filler after proper treatment. Due to the special physical and chemical properties of red mud, such as high liquid limit and high plasticity index, it may affect the stability of soil. Therefore, red mud can be improved by ad...
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Elsevier
2025-07-01
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| Series: | Case Studies in Construction Materials |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2214509524012683 |
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| author | Song Yin Siyue Zheng Xinming Li Zhiliu Wang Pan Yan Ya He Yuru Li |
| author_facet | Song Yin Siyue Zheng Xinming Li Zhiliu Wang Pan Yan Ya He Yuru Li |
| author_sort | Song Yin |
| collection | DOAJ |
| description | Red mud is a kind of solid waste, which can be used as engineering roadbed filler after proper treatment. Due to the special physical and chemical properties of red mud, such as high liquid limit and high plasticity index, it may affect the stability of soil. Therefore, red mud can be improved by adding traditional inorganic binders such as lime and fly ash to improve its road performance as roadbed filler. Red mud-based modified silty sand subgrade filler will be affected by dry-wet alternation caused by various factors in practical application, thus affecting the durability of the material. In order to study the strength degradation characteristics and microstructure changes of red mud, lime and fly ash modified silty sand subgrade filler after dry-wet cycle, the samples of different curing ages were subjected to 0 ∼ 10 dry-wet cycles, and their compressive strength, microstructure and environmental control indexes were tested and analyzed. The results show that the sample cured for 90 days has the strongest toughness and the best ability to resist dry and wet deformation. With the increase of the number of dry-wet cycles, the mass loss rate of the sample is in the range of 6∼7 %, and the unconfined compressive properties and tensile properties decrease first and then increase. There are continuous hydration reactions and pozzolanic reactions in the soil, but the degree of physical damage in the early stage of the dry-wet cycle is large, and the later cementitious products have a certain offsetting effect on the structural damage. The internal cracks of the sample without dry-wet cycle are less and the structure is dense. After the dry-wet cycle, the microstructure of the sample changed greatly, and the cracks increased and showed different forms. Through SEM image analysis, it was found that the pore structure of the sample changed during the dry-wet cycle, which corresponded to the change law of mechanical properties. After wetting-drying cycles, the leaching concentration of heavy metals in the modified soil increased slightly, but the overall concentration value was low, which was not a toxic substance and could be used as a roadbed material. The study reveals the influence of dry-wet cycle on the strength characteristics and microstructure of red mud, lime and fly ash synergistically improved silty sand, which provides a technical reference for the engineering application of red mud-based materials. |
| format | Article |
| id | doaj-art-8c7fc831d6e5498a82c2a3ee209c9531 |
| institution | Kabale University |
| issn | 2214-5095 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Case Studies in Construction Materials |
| spelling | doaj-art-8c7fc831d6e5498a82c2a3ee209c95312024-12-14T06:31:21ZengElsevierCase Studies in Construction Materials2214-50952025-07-0122e04116Strength characteristics and microstructure of silty sand improved by red mud, lime and fly ash under dry-wet cycleSong Yin0Siyue Zheng1Xinming Li2Zhiliu Wang3Pan Yan4Ya He5Yuru Li6School of Intelligent Construction and Civil Engineering, Zhongyuan University of Technology, 41 Zhongyuan Road, Zhengzhou 450007, PR ChinaSchool of Intelligent Construction and Civil Engineering, Zhongyuan University of Technology, 41 Zhongyuan Road, Zhengzhou 450007, PR ChinaCorresponding author.; School of Intelligent Construction and Civil Engineering, Zhongyuan University of Technology, 41 Zhongyuan Road, Zhengzhou 450007, PR ChinaSchool of Intelligent Construction and Civil Engineering, Zhongyuan University of Technology, 41 Zhongyuan Road, Zhengzhou 450007, PR ChinaSchool of Intelligent Construction and Civil Engineering, Zhongyuan University of Technology, 41 Zhongyuan Road, Zhengzhou 450007, PR ChinaSchool of Intelligent Construction and Civil Engineering, Zhongyuan University of Technology, 41 Zhongyuan Road, Zhengzhou 450007, PR ChinaSchool of Intelligent Construction and Civil Engineering, Zhongyuan University of Technology, 41 Zhongyuan Road, Zhengzhou 450007, PR ChinaRed mud is a kind of solid waste, which can be used as engineering roadbed filler after proper treatment. Due to the special physical and chemical properties of red mud, such as high liquid limit and high plasticity index, it may affect the stability of soil. Therefore, red mud can be improved by adding traditional inorganic binders such as lime and fly ash to improve its road performance as roadbed filler. Red mud-based modified silty sand subgrade filler will be affected by dry-wet alternation caused by various factors in practical application, thus affecting the durability of the material. In order to study the strength degradation characteristics and microstructure changes of red mud, lime and fly ash modified silty sand subgrade filler after dry-wet cycle, the samples of different curing ages were subjected to 0 ∼ 10 dry-wet cycles, and their compressive strength, microstructure and environmental control indexes were tested and analyzed. The results show that the sample cured for 90 days has the strongest toughness and the best ability to resist dry and wet deformation. With the increase of the number of dry-wet cycles, the mass loss rate of the sample is in the range of 6∼7 %, and the unconfined compressive properties and tensile properties decrease first and then increase. There are continuous hydration reactions and pozzolanic reactions in the soil, but the degree of physical damage in the early stage of the dry-wet cycle is large, and the later cementitious products have a certain offsetting effect on the structural damage. The internal cracks of the sample without dry-wet cycle are less and the structure is dense. After the dry-wet cycle, the microstructure of the sample changed greatly, and the cracks increased and showed different forms. Through SEM image analysis, it was found that the pore structure of the sample changed during the dry-wet cycle, which corresponded to the change law of mechanical properties. After wetting-drying cycles, the leaching concentration of heavy metals in the modified soil increased slightly, but the overall concentration value was low, which was not a toxic substance and could be used as a roadbed material. The study reveals the influence of dry-wet cycle on the strength characteristics and microstructure of red mud, lime and fly ash synergistically improved silty sand, which provides a technical reference for the engineering application of red mud-based materials.http://www.sciencedirect.com/science/article/pii/S2214509524012683Red mudLime fly ashSilty sandDry-wet cyclesUnconfined compressive strengthMicroscopic mechanism |
| spellingShingle | Song Yin Siyue Zheng Xinming Li Zhiliu Wang Pan Yan Ya He Yuru Li Strength characteristics and microstructure of silty sand improved by red mud, lime and fly ash under dry-wet cycle Case Studies in Construction Materials Red mud Lime fly ash Silty sand Dry-wet cycles Unconfined compressive strength Microscopic mechanism |
| title | Strength characteristics and microstructure of silty sand improved by red mud, lime and fly ash under dry-wet cycle |
| title_full | Strength characteristics and microstructure of silty sand improved by red mud, lime and fly ash under dry-wet cycle |
| title_fullStr | Strength characteristics and microstructure of silty sand improved by red mud, lime and fly ash under dry-wet cycle |
| title_full_unstemmed | Strength characteristics and microstructure of silty sand improved by red mud, lime and fly ash under dry-wet cycle |
| title_short | Strength characteristics and microstructure of silty sand improved by red mud, lime and fly ash under dry-wet cycle |
| title_sort | strength characteristics and microstructure of silty sand improved by red mud lime and fly ash under dry wet cycle |
| topic | Red mud Lime fly ash Silty sand Dry-wet cycles Unconfined compressive strength Microscopic mechanism |
| url | http://www.sciencedirect.com/science/article/pii/S2214509524012683 |
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