{"title":"Properties of saline soil stabilized with fly ash and modified aeolian sand","authors":"Yuanqing Chen , Akelamjiang. maimait , Jianjun Cheng , Yanfu Duan , Dawei Yin , Hongguang Dong , Yupeng Li","doi":"10.1016/j.cscm.2024.e03503","DOIUrl":null,"url":null,"abstract":"<div><p>Against the backdrop of saline soil solidification and the resource utilization of solid waste and aeolian sand in cold and arid regions, this study employs locally accessible fly ash and aeolian sand to solidify saline soil. By combining unconfined compressive strength tests, X-ray diffraction analysis, scanning electron microscopy, orthogonal experiments, and single-factor analysis, the strength characteristics, mineral composition, and interfacial structure changes of saline soil solidified with different freeze-thaw cycles and varying amounts of fly ash, aeolian sand, and alkali activators were investigated. The effects of each factor were analyzed to determine the optimal mixture ratio and to explore the solidification mechanism.The results indicate that the unconfined compressive strength of saline soil is most significantly enhanced when solidified with a combination of fly ash, aeolian sand, and alkali activators. The optimal mixture ratio was found to be 24 % fly ash, 7 % aeolian sand, and 4.5 mol/L alkali activator. With the incorporation of these solidifying materials, the failure mode of saline soil transitions from plastic to brittle, and the stress-strain curve exhibited a strain-softening behavior. The combined solidification method demonstrated the most pronounced effect in mitigating freeze-thaw damage, with the unconfined compressive strength of the solidified soil reaching 7.01 MPa after seven freeze-thaw cycles, compared to 0.03 MPa for the untreated soil, an increase by a factor of 234.This significant enhancement is attributed to the formation of substantial gel substances, which mitigate the strength loss caused by freeze-thaw cycles. The gel locking mechanism between particles in the solidified soil far exceeds the detrimental effects of freeze-thaw cycles, effectively inhibiting freeze-thaw deterioration. Additionally, the reaction pathways involving AFt and AFm phases reduce the content of SO<sub>4</sub><sup>2-</sup> and Cl<sup>-</sup> in the solidified soil, effectively suppressing salt expansion and significantly improving the soil's strength.</p></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":null,"pages":null},"PeriodicalIF":6.5000,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2214509524006545/pdfft?md5=78293de8dcc062e7f27444e3070e2a5a&pid=1-s2.0-S2214509524006545-main.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Case Studies in Construction Materials","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2214509524006545","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CONSTRUCTION & BUILDING TECHNOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Against the backdrop of saline soil solidification and the resource utilization of solid waste and aeolian sand in cold and arid regions, this study employs locally accessible fly ash and aeolian sand to solidify saline soil. By combining unconfined compressive strength tests, X-ray diffraction analysis, scanning electron microscopy, orthogonal experiments, and single-factor analysis, the strength characteristics, mineral composition, and interfacial structure changes of saline soil solidified with different freeze-thaw cycles and varying amounts of fly ash, aeolian sand, and alkali activators were investigated. The effects of each factor were analyzed to determine the optimal mixture ratio and to explore the solidification mechanism.The results indicate that the unconfined compressive strength of saline soil is most significantly enhanced when solidified with a combination of fly ash, aeolian sand, and alkali activators. The optimal mixture ratio was found to be 24 % fly ash, 7 % aeolian sand, and 4.5 mol/L alkali activator. With the incorporation of these solidifying materials, the failure mode of saline soil transitions from plastic to brittle, and the stress-strain curve exhibited a strain-softening behavior. The combined solidification method demonstrated the most pronounced effect in mitigating freeze-thaw damage, with the unconfined compressive strength of the solidified soil reaching 7.01 MPa after seven freeze-thaw cycles, compared to 0.03 MPa for the untreated soil, an increase by a factor of 234.This significant enhancement is attributed to the formation of substantial gel substances, which mitigate the strength loss caused by freeze-thaw cycles. The gel locking mechanism between particles in the solidified soil far exceeds the detrimental effects of freeze-thaw cycles, effectively inhibiting freeze-thaw deterioration. Additionally, the reaction pathways involving AFt and AFm phases reduce the content of SO42- and Cl- in the solidified soil, effectively suppressing salt expansion and significantly improving the soil's strength.
期刊介绍:
Case Studies in Construction Materials provides a forum for the rapid publication of short, structured Case Studies on construction materials. In addition, the journal also publishes related Short Communications, Full length research article and Comprehensive review papers (by invitation).
The journal will provide an essential compendium of case studies for practicing engineers, designers, researchers and other practitioners who are interested in all aspects construction materials. The journal will publish new and novel case studies, but will also provide a forum for the publication of high quality descriptions of classic construction material problems and solutions.