needle punched GCL geosynthetic clay layer(GCL) is a waterproofing material,made of compound geotextile,non woven geotextile with expansion bentonite in ... There are many small fibre space in GCL after being needle punched,then the bentonite powder can not more in ... water leakage efficiently. Specification: GCN-NP,needle punched GCL; GCL-OF,needle punched GCL coated with film; GCL-AH adhensive GCL.Unit ...