This study analyzes a hydraulic performance of GCL (geosynthetic clay liners) with and without swelling accelerating material, SAP(Super Absorbent Polymer). In the evaluation of hydraulic performance of GCL, free swell index and triaxial compression permeability tester were used by falling head permeability tester in the evaluation of hydraulic performance with the mixed soil of decomposed granite and bentonite. Permittivity of weathered granite soil and bentonite mixture was increased with SAP content and permeability of this mixture soil was also increased till bentonite content 10%.