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