Effect of geomembrane texturing method on geomembrane-dry GCL interface shear behavior

Effect of geomembrane texturing method on interface shear behavior between textured geomembranes (GM) and the nonwoven side of a dry geosynthetic clay liner (GCL) was evaluated using large-scale direct shear tests conducted using geomembranes with four different types of texturing and a range of asperity heights: impinged texturing (GMTI), coextruded texturing (GMTC), low asperity embossed texturing (GMTE_L), and high asperity embossed texturing (GMTE_H). The GCL contained granular bentonite between woven and nonwoven geotextiles bonded by needlepunching. Tests were conducted on the dry GCL to isolate GM-GCL interface behavior from other factors. All interfaces exhibited similar strain-softening shear behavior. Type of texturing had a strong influence on GM-GCL interface behavior. Comparable shear-displacement curves involving direct surface engagement between the texturing asperities and geotextile fibers were obtained with GMTI and GMTC. GMTI texturing delaminated during shear, reducing geotextile combing compared to GMTC. The GMTE_L engaged the geotextile on the GCL via tip penetration and surface friction, as evinced by striations on the GCL surface, resulting in the lowest interface strengths of the textured GMs. GMTE_H engaged deep into the interior of the GCL, resulting in dilation, tearing of the geotextile, furrows in the bentonite, and the highest interface strength of those tested.