Mixture of excavated Callovo-Oxfordian (COx) argillite and MX80 bentonite has been proposed as potential sealing material for the French deep geological disposal facility of radioactive waste. The mixtures hydro-mechanical behaviour was studied in order to assess their response on design requirements. At the as-compacted state, soil fabric analysed by the MIP technique, showed single-modal pore distribution for pure COx and bimodal pore distribution for samples containing MX80. All tested mixtures developed homogeneous behaviour during compaction with no effect of MX80 presence. Swelling potential was evaluated by hydration tests under 4 MPa on highly compacted material (2.0 Mg/m³). Swelling increase and saturated permeability reduction was obtained on bentonite content increment. Combining results of the present experimental work and remarks of previous researchers, the characteristic saturation potential slope was determined and exploited to estimate the swelling under 1, 4 and 7 MPa for various COx/MX80 mixtures compacted at different pressures. The experimental verification of the adopted method suggested an approach of identifying possible combinations in terms of compaction and bentonite content that can fulfill design requirements.

已提出将挖掘的卡洛沃-牛津（COx）泥石与MX80膨润土的混合物用作法国放射性废物深部地质处置设施的潜在密封材料。为了评估混合物对设计要求的响应，研究了混合物的流体力学行为。在密实状态下，通过MIP技术分析的土壤织物显示出纯COx的单峰孔隙分布和含有MX80的样品的双峰孔隙分布。所有测试的混合物在压实过程中均表现出均匀的行为，而没有MX80的存在。通过在4 MPa下对高度压实的材料（2.0 Mg / m ³）。随着膨润土含量的增加，膨胀率增加，饱和渗透率降低。结合当前实验工作的结果和先前研究人员的评论，确定了特征饱和电势斜率，并用于估算在不同压力下压实的各种COx / MX80混合物在1、4和7 MPa下的溶胀。对所采用方法的实验验证提出了一种方法，该方法可以确定能够满足设计要求的压实度和膨润土含量。