The French long-term repository for intermediate level/long lived nuclear wastes consists in a network of underground concrete tunnels in deep geological medium. Various loadings will occur during the repository service-life. Among the physical constraints, especially de-saturation/re-saturation processes, pore pressure variations…
The French long-term repository for intermediate level/long lived nuclear wastes consists in a network of underground concrete tunnels in deep geological medium. Various loadings will occur during the repository service-life. Among the physical constraints, especially de-saturation/re-saturation processes, pore pressure variations and temperature changes will affect the concrete properties. The de-saturation process is linked to relative humidity decreases, and in relation to temperature variations. De-saturation leads to shrink- age strains that often induce micro-cracking. Micro-cracks can increase the concrete permeability and de- crease the mechanical properties. This experimental study focuses on the drying process and its conse- quences. The studied materials are concretes, based on CEM I or CEM V/A-type cements. The influence of temperature and cement composition upon drying shrinkage is shown to be important. Due to this, transport properties depend on cement composition. An increase in temperature of up to 80°C accelerates drying mechanisms by means of thermal activation.