A specific setup to study hydration and dehydration of COx argillite at applied stresses

This article presents a specific experimental setup to study the hydration and dehydration of Callovo-Oxfordian (COx) argillite, which is considered as a possible host rock formation for radioactive nuclear waste at great depth in France. Argillite will swell during hydration and contract during dehydration, which is a key geotechnical process during the excavation and open-drift stages of a nuclear waste repository. Studies show that the partially saturated properties of argillite depend strongly on both water content and mechanical loading. In order to study the coupled hydro-mechanical behaviour of COx argillite, a specific experimental setup was developed. This new system can be used to carry out hydration and dehydration tests under controlled mechanical loading. The developed setup continuously records not only relative humidity, stress and deformation, but also the sample weight. Hydration and dehydration testing carried out on COx argillite confirms the performance of the specific setup.