Compacted block composed of 70% crushed Callovo-Oxfordian claystone and 30% MX80 bentonite has been proposed as a possible material for sealing a potential repository of radioactive waste. In this study, the compaction property of the bentonite/claystone mixtures with various bentonite fractions and water contents were first investigated to define an appropriate protocol for the fabrication of blocks. Results show that the increase of bentonite fraction decreased the overall compressibility and the achievable dry density at a given stress. As the water content increased, the compressibility at a relatively low vertical stress increased due to the increasing deformability of aggregates and the decreasing inter-aggregate friction; contrarily, at a high vertical stress, a lower compressibility was observed for the samples with a higher water content because a larger stress was required to squeeze water within aggregates. During demoulding, the required demoulding pressure increased with the increase of bentonite fraction and decreased with the increasing water content. Then, to assess the suitability of the material, the swelling pressures and hydraulic conductivities of the compacted blocks were determined. It was found that the swelling pressure increased and the hydraulic conductivity decreased with the increases of bentonite fraction and dry density. By contrast, as the water content increased, more water was intercalated in the interlayer spaces and the inter-aggregate pore volume decreased, resulting in reductions of the swelling pressure and hydraulic conductivity.

有人提出由70％的卡洛沃-牛津破碎粘土和30％的MX80膨润土组成的压实砌块作为密封潜在放射性废物库的可能材料。在这项研究中，首先研究了具有各种膨润土含量和水含量的膨润土/粘土混合物的压实性能，以定义合适的规程来制造砌块。结果表明，在给定应力下，膨润土含量的增加降低了总体可压缩性和可达到的干密度。随着水含量的增加，由于骨料的可变形性增加和骨料间的摩擦力减小，在较低垂直应力下的可压缩性也增加了。相反，在高垂直应力下，对于含水量较高的样品，观察到较低的可压缩性，因为将较大的应力挤压集料中的水。脱模过程中，所需的脱模压力随膨润土含量的增加而增加，随水含量的增加而降低。然后，为了评估材料的适用性，确定压实块的溶胀压力和水力传导率。发现膨润土分数和干密度的增加，溶胀压力升高，水力传导率降低。相反，随着水含量的增加，更多的水被插入层间空间中，并且聚集体之间的孔体积减小，导致溶胀压力和水力传导率降低。