两种高庙子钠基膨润土膨胀特性比较研究

对两种高庙子钠基膨润土（简称GMZ001和GMZ07）在不同初始干密度下进行膨胀力试验、常压力下的膨胀变形试验以及压缩试验。试验结果表明，GMZ001的膨胀能力要比GMZ07的大，并且GMZ001比GMZ07更难压实。对饱和后两种膨润土进行压汞试验和扫描电子显微镜测试后发现，在相同孔隙比下，GMZ07集聚体间孔隙较多，并且GMZ001集聚体的水化程度大于GMZ07。结合土工和微观试验的结果，认为导致两者力学性能差异的主要原因是由于颗粒粒径大小的差异以及蒙脱石含量的不同。最后利用蒙脱石孔隙比的概念对两种膨润土的浸水膨胀试验结果进行归一化，并对膨润土的膨胀特性进行了预测。

Comparison between swelling properties of two Gaomiaozi Na-bentonites

In China, Gaomiaozi (GMZ) bentonite has been chosen as a potential buffer/backfill material for deeply buried geological disposal system to isolate the high-level radioactive wastes (HLW). A series of laboratory tests (including swelling pressure test, swelling deformation test and compression test) on two GMZ Na-bentonites (called as GMZ001 and GMZ07) is performed at different initial dry densities. The test results show that GMZ001 has larger swelling pressure than GMZ07 at the same void ratio and is harder to be compressed than GMZ07. On the other hand, the microstructural features of two GMZ Na-bentonites in saturated state are investigated by combining the mercury intrusion porosimetry (MIP) tests and scanning electronic microscope (SEM) observations. The test results reveal that GMZ07 has more inter-aggregate pores than GMZ001 at the same void ratio, and the aggregates of GMZ001 is characterized by more strong hydration compared to GMZ07. The difference in mechanical behavior of two GMZ Na-bentonites is due to differences in the grain size and montmorillonite content. Furthermore, based on the concept of the montmorillonite void ratio, the results of swelling test on two GMZ bentonites under fully saturated condition can be expressed by a unique line, and the predictions of the swelling pressure and deformation are conducted for two bentonites.