Because of its solid structure, low permeability, slow diffusion and good chemical retention for many radionuclides, cementitious materials are often used for conditioning radioactive waste and are omnipresent in many radioactive waste disposal facility concepts as engineered barriers. Cementitious materials are not in geochemical equilibrium with the surrounding disposal environment and will undergo slow but significant geochemical, physical and mechanical changes. The evolution and the consequences on their performance have to be assessed over extreme long time scales ranging from a few hundreds of years to several tens of thousands of years. For a deep understanding of the long-term geochemical and microstructural alteration processes, a synergy between (i) experimental studies, (ii) multi-scale modelling and (iii) coupled reactive transport models is necessary and a prerequisite to assess the long-term performance. This paper presents an overview of some recent developments in these three approaches. From an experimental point of view, well-designed accelerated degradation tests are required as a basis for mineralogical and microstructural characterization and for measurement of macroscale properties as diffusion coefficient, permeability and water sorptivity. From multiscale modelling perspective, deployment of thermodynamic model, continuum scale, mesoscale and pore scale models are key to advancing the understanding of material evolution. In particular, an overview of pore-scale models is presented that explicitly accounts for the heterogeneity of cement paste for calculating flow, transport and ageing processes and effects on microstructure and macroscopic properties. Some of these developments are discussed in the context of long-term carbonation and leaching of cementitious materials. Finally, the paper discusses opportunities in the context of immobilization of waste, including some recent modelling work.

由于其固体结构、低渗透性、缓慢扩散和对许多放射性核素的良​​好化学保留，胶结材料经常用于处理放射性废物，并且在许多放射性废物处置设施概念中作为工程屏障无处不在。胶结材料与周围处置环境不处于地球化学平衡，将经历缓慢但显着的地球化学、物理和机械变化。必须在几百年到几万年的极长时间尺度上评估其性能的演变和后果。为了深入了解长期地球化学和微观结构蚀变过程，（i）实验研究之间的协同作用，(ii) 多尺度建模和 (iii) 耦合反应传输模型是评估长期性能的必要条件和先决条件。本文概述了这三种方法的一些最新进展。从实验的角度来看，需要精心设计的加速降解测试作为矿物学和微观结构表征以及测量扩散系数、渗透性和吸水性等宏观特性的基础。从多尺度建模的角度来看，热力学模型、连续尺度、中尺度和孔隙尺度模型的部署是推进对材料演化理解的关键。特别是，对孔隙尺度模型进行了概述，该模型明确说明了用于计算流量的水泥浆的异质性，运输和老化过程以及对微观结构和宏观性能的影响。其中一些发展是在胶结材料的长期碳化和浸出的背景下讨论的。最后，本文讨论了废物固定化方面的机会，包括最近的一些建模工作。