采用地聚合物对黄土进行固化,通过三轴试验研究了硫酸盐侵蚀作用下固化黄土抗剪强度的劣化规律,结合电镜扫描分析了固化土的劣化机理。结果表明:掺入地聚合物可有效提升固化黄土的抗盐蚀性能,掺量越大,抗侵蚀性能提高越显著;随盐蚀时间增加,地聚合物固化黄土抗剪强度呈线性劣化趋势;盐蚀60 d后15%、20%固化土仍具有未扰动试样峰值偏应力的70%、77%,表现出良好的抗盐蚀性,但10%固化土劣化程度较高,其只具有未扰动试样峰值偏应力的45.4%,峰值偏应力下降明显,固化结构已有部分丧失;随盐蚀时间增加,60 d时15%和20%地聚合物固化土黏聚力仍保有初始值的70%以上,但10%地聚合物固化土劣化显著,降幅约为50%;盐蚀作用对内摩擦角的影响相对较小,盐蚀60 d后10%、15%和20%地聚合物固化土内摩擦角分别降低了22.7%、13.3%和8.6%;电镜扫描发现硫酸盐溶液对地聚合物固化黄土的结构劣化表现为:短期内孔隙水侵蚀作用较为显著,长期浸泡过程中硫酸根离子会与地聚合物反应,导致水化产物分解,故宏观强度下降。
Geopolymer was employed to stabilize loess, and the degradation behavior of its shear strength under sulfate erosion was investigated through triaxial tests, and scanning electron microscopy analysis was conducted to further understand the degradation mechanism of the stabilized loess. The results show that: The incorporation of geopolymer can effectively improve the salt erosion resistance of cured loess, and the higher the incorporation rate, the more significant the improvement of erosion resistance. With the increase of salt erosion time, the shear strength of geopolymer-stabilized loess shows a linear deterioration trend. After 60 days of salt corrosion, 15% and 20% stabilized soil still possess 70% and 77% of the peak partial stress of undisturbed specimens, showing good salt corrosion resistance. However, the degradation degree of 10% solidified soil is relatively high, with only 45.4% of the peak deviatoric stress of undisturbed samples. The peak deviatoric stress decreases significantly, and the solidified structure has been partially lost. At 60 days, the cohesion of 15% and 20% solidified soil can still retain more than 70% of their original values, but the 10% geopolymer solidified soil deteriorates significantly, with a decrease of about 50%. The effect of salt erosion on the internal friction angle is relatively small, which decreases by 22.7%, 13.3% and 8.6% respectively for 10%, 15% and 20% geopolymer stabilized loess. The scanning electron microscopy analysis shows that the structural deterioration of geopolymer solidified loess caused by sulfate solution is manifested in two aspects: In the short term, the pore water erosion is more significant;In the long-term immersion process, sulfate ion reacts with GP, resulting in the decomposition of hydration products, therefore the macro strength decreases.
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