Properties of saline soil stabilized with fly ash and modified aeolian sand

IF 6.5 2区 工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY
Yuanqing Chen , Akelamjiang. maimait , Jianjun Cheng , Yanfu Duan , Dawei Yin , Hongguang Dong , Yupeng Li
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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.

用粉煤灰和改良风化砂稳定盐碱土的特性
本研究以寒冷干旱地区盐碱土固化及固体废弃物和风化砂资源化利用为背景,采用当地可获得的粉煤灰和风化砂固化盐碱土。通过无约束抗压强度试验、X 射线衍射分析、扫描电子显微镜、正交实验和单因素分析等方法,研究了不同冻融循环和不同粉煤灰、风化砂、碱活化剂用量下固结盐渍土的强度特性、矿物组成和界面结构变化。结果表明,在粉煤灰、沸砂和碱活化剂的共同作用下,盐碱土的无侧限抗压强度得到了最显著的提高。最佳混合比例为 24%粉煤灰、7%风化砂和 4.5 mol/L 碱活化剂。加入这些固化材料后,盐碱土的破坏模式从塑性转变为脆性,应力-应变曲线呈现应变软化行为。组合固化法在减轻冻融破坏方面的效果最为明显,经过 7 次冻融循环后,固化土壤的无压抗压强度达到 7.01 兆帕,而未处理土壤的无压抗压强度仅为 0.03 兆帕,增加了 234 倍。凝固土壤中颗粒之间的凝胶锁定机制远远超过了冻融循环的有害影响,有效抑制了冻融恶化。此外,AFt 和 AFm 相的反应途径降低了固化土壤中 SO42- 和 Cl- 的含量,有效抑制了盐膨胀,显著提高了土壤强度。
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来源期刊
CiteScore
7.60
自引率
19.40%
发文量
842
审稿时长
63 days
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.
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