A compacted mixture of Callovo-Oxfordian (COx) claystone/MX80 bentonite is a promising sealing material in the French Cigéo project for radioactive waste disposal at great depth. Over time, the sealing material will be saturated by the site water originating from the surrounding rock and the water chemistry can affect the performance of the sealing material. In this study, the effects of water chemistry and technological gaps on the hydro-mechanical property were investigated by performing hydration tests on the compacted claystone/bentonite mixture with technological gaps using deionised water and synthetic site solution for 10 and 590 days. After the tests, the dry density, water content and microstructure distributions were also determined to complement the program. Results show that the synthetic site solution did not affect the swelling pressure and hydraulic conductivity after a short term of 10 days. With the increase of hydration time, the specimens with technological gaps tended to be homogeneous, resulting in a reduction of hydraulic conductivity. Because of the cation exchanges and the decreased diffuse double layer thickness, the synthetic site solution reduced the swelling pressure and increased the hydraulic conductivity in long term, especially for the specimens with lower global dry densities.

Callovo-Oxfordian (COx) 粘土岩/MX80 膨润土的压实混合物是法国 Cigéo 项目中用于大深度放射性废物处置的有前途的密封材料。随着时间的推移，密封材料将被源自围岩的现场水饱和，水化学会影响密封材料的性能。在这项研究中，通过使用去离子水和合成场地溶液对具有技术间隙的压实粘土/膨润土混合物进行水化试验，研究了水化学和技术差距对水力学性能的影响，为期 10 天和 590 天。测试后，还确定了干密度、含水量和微观结构分布，以补充该程序。结果表明，合成场地溶液在 10 天的短期内没有影响膨胀压力和导水率。随着水化时间的增加，存在技术差距的试件趋于均质化，导致导水率降低。由于阳离子交换和扩散双层厚度的减小，合成位点溶液长期降低了膨胀压力并提高了导水率，特别是对于整体干密度较低的试样。