Clay geosynthetic barriers (GBR-Cs) used in landfill covers must ensure lining on the long term. The primary mode of ageing of bentonite GBR-Cs in covers is the coupling of cation exchange and hydrationdesiccation cycles. The objective of this paper is to synthesize the optimal conditions to prevent a loss of performance of GBR-Cs in covers with time, based on a literature review. Various parameters will be discussed. The literature review will put in light the lack of consistent information from study to study. This enforces the need for a list of information to collect in future excavations. Such a list is proposed in the third section of this paper followed by the presentation of results from recent excavations performed by the first author.