为探讨硫酸盐含量对全固废材料固化盐渍土抗压强度及微观结构的影响,采用击实试验和无侧限抗压强度试验,并结合扫描电镜、EDS、X射线衍射和热重分析等微观测试结果,从固化盐渍土的火山灰反应产物及其数量等角度分析含盐量对固化盐渍土抗压强度变化的影响。结果表明:硫酸盐含量低于2.7%时,固化盐渍土抗压强度随含盐量的增加呈先增大后减小,抗压强度峰值对应的含盐量为1.8%;固化盐渍土的火山灰反应产物主要为C-S-H和AFt,硫酸盐含量从0.3%增至1.8%时,反应产物明显增多,致使固化土抗压强度增大;但当硫酸盐含量从1.8%增至2.7%时,膨胀性AFt将试件内部孔隙完全填充并产生胀裂破坏,造成抗压强度降低。研究成果为全固废材料固化硫酸盐渍土的工程应用奠定了基础,对环境保护也有积极贡献。
Abstract
The aim of this study is to investigate the influence of sulfate content on compressive strength and microstructure of solidified saline soil with solid waste materials. The impact of salinity on compressive strength of solidified saline soil was examined from the viewpoint of pozzolanic products and quantities via compaction test and unconfined compressive strength test in association with scanning electron microscopy (SEM), energy dispersive spectrom(EDS), X-ray diffraction (XRD) and thermogravimetric analysis. Results demonstrated that when the content of sulfate was lower than 2.7%, the compressive strength of solidified saline soil increased at first and then decreased with the increase of salinity. When salinity was 1.8%, compressive strength reached peak value. The major pozzolanic products of solidified saline soil are C-S-H and AFt. When the content of sulfate augmented from 0.3% to 1.8%, the reaction products increased obviously, resulting in the rising of compressive strength of solidified soil; however, when the content of sulfate increased from 1.8% to 2.7%, the internal pores of the specimen were completely filled by expansive AFt, giving rise to cracks and the decline of compressive strength. The research findings laid a foundation for the engineering application of solidified sulphate saline soil.
关键词
固化盐渍土 /
全固废材料 /
硫酸盐含量 /
无侧向抗压强度 /
微观结构
Key words
solidified saline soil /
all-solid waste material /
sulfate content /
unconfined compressive strength /
microstructure
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基金
国家自然科学基金项目(51869031);“水利工程”重点学科研究项目(SLXK-YJS-2018-06)
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