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通过系列室内试验,研究了硫酸盐长期浸泡环境下GGBS-Mg O固化黏土的物理和力学性质及微观特征变化规律,并与水泥固化黏土进行对比,揭示了GGBS-Mg O固化黏土抵抗硫酸盐侵蚀的机制。与水泥固化黏土相比,硫酸盐浸泡条件下GGBS-Mg O固化黏土表面完整度较好;质量变化率在浸泡120 d时仅为水泥固化黏土的0.25倍;固化黏土体p H略小于同期水泥固化黏土;浸泡初期GGBS-Mg O固化黏土强度增长达20%,同周期时无侧限抗压强度较水泥固化黏土高15%~80%。X射线衍射试验(XRD)表明,硫酸盐侵蚀下GGBS-Mg O固化黏土中水化硅酸钙(C-S-H凝胶)的峰值高于水泥固化黏土,而钙矾石(AFt)的XRD图谱峰值明显低于水泥固化黏土。电镜扫描试验结果表明,两种固化黏土中钙矾石形态明显不同:钙矾石在水泥固化黏土中以团聚型晶体存在,可具较强膨胀性,而在GGBS-Mg O固化黏土中则以细短形态分布于颗粒间,可有效填充试样孔隙,使其具备良好的抗硫酸盐侵蚀能力。
Through a series of laboratory tests, the physical and mechanical properties and microscopic characteristics of GGBS-MgO cured clay under long-term sulphate immersion were studied. Compared with cement-cured clay, GGBS-MgO clay was found to resist sulfate attack Mechanisms. Compared with cemented clay, the surface integrity of GGBS-MgO cemented clay under sulfate immersion was better. The mass change rate was only 0.25 times higher than that of cemented clay at 120 days. The p H of cemented clay was slightly lower than that of cement In the initial period of soaking, the strength of GGBS-MgO cured clay increased by 20%, and the unconfined compressive strength at the same period was 15% -80% higher than that of cement-cured clay. X-ray diffraction (XRD) showed that the peak value of hydrated calcium silicate (CSH gel) in the GGBS-MgO clay was higher than that of the cement-cured clay under sulfate attack, whereas the peak of the XRD spectrum of ettringite (AFt) Lower than cement clay. Electron microscopy results showed that the morphology of ettringite was obviously different between the two types of clay: ettringite existed as agglomerated crystals in the cement-cured clay and had a strong expansibility. In the case of GGBS-MgO clay Smaller form distribution between the particles, which can effectively fill the sample pores, so that it has good resistance to sulfate erosion.