Geomembrane is also called anti-seepage geotextile. It usually refers to a synthetic material made of geotextile woven fabric or plastic woven fabric bonded with a membrane. One cloth and one membrane refers to a layer of geotextile adhered to a layer of membrane. Two cloths and one membrane refers to a membrane sandwiched between two layers of geotextile. Two membranes and one cloth refers to a geotextile sandwiched between two membranes.
From the perspective of production steps, geomembranes need to produce two finished products: geotextile and membrane respectively, and then bond one or more finished products according to the specifications, and finally become the finished geomembrane. Since geomembranes are not formed in one go, geomembranes have higher requirements for each production process than a single geotextile.