Abstract The Engineered Barrier System (EBS) implemented in full-scale experiments are designed to provide an understanding of the long-term performance of Deep Geological Repositories (DGR) as nuclear waste repositories. The existing interfaces between the engineered barrier materials, such as concrete and bentonite, constitute reactive surfaces on which the thickness and intensity of degradation of the material, which may affect the confinement properties, are under investigation. This study focuses on a concrete projected on a saturated compacted bentonite from the in situ FEBEX experiment, emplaced in the Grimsel Test Site (GTS, Switzerland) and dismantled during 2015 after 13 years of functioning. Preserved sections crossing the interface have shown macroscopic heterogeneities in 1–2 cm of the shotcrete from the contact with bentonite that presumably affected the porosity distribution. In this area, the distribution of mineral and chemical components has been analyzed in detail, both in concrete that is distant from the interface and in contact with the bentonite. The information provided by detailed mineralogical mappings was consistent with quantitative chemical analysis. Chemical mappings are used to explain the distribution, nature and evolution of the phases in the concrete at the interface with clay. The role of porosity, presumably affected by the initial application of the shotcrete, has influenced the characteristic geochemical reactions in the bentonite-concrete interaction. The chemical composition of di- and tri-octahedral Al–Mg smectites, in the mixing trend of high-charge beidellite-saponite, were identified in the concrete in the degraded area at the interface.

中文翻译：

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来自 FEBEX 实验的 13 年原位混凝土/膨润土相互作用中的混凝土扰动。界面处 2:1 Mg 层状硅酸盐沉淀的新见解

摘要 在全尺寸实验中实施的工程屏障系统 (EBS) 旨在提供对深地质处置库 (DGR) 作为核废料处置库的长期性能的理解。工程阻隔材料（例如混凝土和膨润土）之间的现有界面构成了反应表面，正在研究可能影响限制性能的材料降解的厚度和强度。本研究的重点是投射在来自原位 FEBEX 实验的饱和压实膨润土上的混凝土，放置在 Grimsel 试验场（GTS，瑞士），并在运行 13 年后于 2015 年拆除。穿过界面的保存部分在与膨润土接触的 1-2 厘米喷射混凝土中显示出宏观不均匀性，这可能影响了孔隙率分布。在该区域，详细分析了矿物和化学成分的分布，包括远离界面的混凝土和与膨润土接触的混凝土。详细矿物图谱提供的信息与定量化学分析一致。化学映射用于解释混凝土与粘土界面处相的分布、性质和演变。孔隙率的作用，大概受喷射混凝土初始应用的影响，影响了膨润土-混凝土相互作用中的特征地球化学反应。