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Geosynthetic clay liners (GCLs) are widely used as hydraulic barrier to isolate waste disposal facilities thanks to their low permeability to water. In the field, the efficiency of GCLs can be altered by cation exchange and highly concentrated solutions during contact with aggressive liquids and by the desiccation caused by seasonal temperature changes. Wet and dry cycles lead to desiccation and cracking of the bentonite. As a consequence, the self-healing capacity, the swelling ability and the hydraulic conductivity are impaired, hence leading to cracking of the bentonite and contamination of the ground. HYPER clay is a polymer modified bentonite developed to provide enhanced performance in presence of electrolyte solutions. In this paper, the effect of different drying temperatures on the swelling ability (air, 40°C and 60°C) and hydraulic conductivity (40°C, 60°C and 105°C) of powder and GCLs prototypes containing HYPER clay and untreated clay subjected to wet-dry cycles with seawater were investigated and compared. Test results showed that the drying temperature plays an important role on the crack formation and self-healing time of the tested materials. The HYPER clay treatment improved the swelling ability and self-healing capacity of the bentonite subjected to wet and dry cycles. Moreover, the permeability of the GCLs containing HYPER clay was lower than that of the untreated bentonite after four wet-dry cycles.