高庙子膨润土膨胀力时效性试验研究

发布时间：2018-08-17 10:51

【摘要】：针对高庙子膨润土在不同含水率和不同干密度条件下膨胀力时效性进行了试验研究。首先采用静力压实法将3种不同含水率的高庙子膨润土粉末压实为两种不同密实状态的试样,随后在保持压实试样的体积和含水率不变的条件下,分别静置0,1,7,15,30和90 d,最后采用膨胀仪对完成静置试样的膨胀力进行量测;同时结合静置过程,完成了部分试样的扫描电镜(SEM)试验。试验结果表明:高庙子膨润土的膨胀力随静置时间的增长不断减小,且前期减小明显,后期逐渐趋于稳定;膨胀力的时效性与试样初始条件有关,试样含水率和干密度越大,膨胀力随静置时间的衰减越明显,即时效性越强。SEM试验结果表明,静置90 d后,高庙子膨润土内的蒙脱石发生了水化,集合体分解,颗粒相互黏结,微观孔隙结构趋于均质化,呈现点阵式的絮状结构;试样静置过程中不同微观结构层次之间的水分重分布导致的蒙脱石水化是高庙子膨润土静置过程中膨胀力降低的主要内在原因。
[Abstract]:The time effect of expansion force of Gaomiaozi bentonite under different moisture content and different dry density was studied experimentally. At first, three kinds of high Miaozi bentonite powder with different moisture content were compacted into two different compacted samples by static compaction method, and then the volume and moisture content of compacted samples were kept constant. At last, the dilatometer was used to measure the expansion force of the static specimen, and the scanning electron microscope (SEM) test of part of the sample was completed in combination with the static process. The experimental results show that the expansion force of Gaomiaozi bentonite decreases with the increase of static time, and decreases obviously in the early stage, and tends to be stable gradually in the later stage, and the time efficiency of expansion force is related to the initial conditions of the sample, the moisture content and dry density of the sample increase. The results of SEM test show that after 90 days of statics, the montmorillonite in Gaomiaozi bentonite is hydrated, aggregates are decomposed, particles are bonded with each other, and the microstructure of pores tends to homogenize. The hydration of montmorillonite caused by water redistribution among different microstructure levels is the main internal reason for the decrease of expansion force in the static process of high temple bentonite.
【作者单位】：同济大学岩土及地下工程教育部重点实验室;教育部城市环境与可持续发展联合研究中心;灾害防控协同创新中心;
【基金】：国家自然科学基金项目(41030748) 国防科工局资助项目(科工计[2011]1051号) 长江学者和创新团队发展计划项目(IRT1029)
【分类号】：TU443

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