Evaluation of Adhesive Seams of High-Density Polyethylene Geomembrane Subjected to Wetting and Freeze-Thaw Cycles

The seaming of geomembranes (GMBs) is a critical aspect of their successful functioning as barriers to liquid, with bonding and welding being the commonly employed methods. Due to the limitations of conventional welding methods at the connection points between the geomembrane and the structure, extrusion welding often results in damage at the seams. The bonding method, which has lower requirements for construction conditions, has emerged as a currently viable alternative seaming technique. Bonding techniques are widely applied in small reservoirs and embankments. This study investigates the performance of high-density polyethylene (HDPE) GMB seams bonded using asphalt-based adhesive (ABA) and non-asphalt-based adhesive (NABA). Seam tensile tests were conducted under wetting and freeze-thaw cycles (FTCs) conditions to evaluate the mechanical properties of the seamed GMBs. The results indicated that the seam strength of specimens bonded with ABA increased as wetting time and FTCs increased (with a maximum increase of 113.8%). In contrast, specimens bonded with NABA exhibited decreased seam strength under similar conditions (with a maximum decrease of 93.4%). Both types of specimens exhibited enhanced seam strength with increasing seam width. Due to wetting and FTCs, the seam efficiency of NABA-bonded specimens decreased, while that of ABA-bonded specimens showed slight improvement. However, the improved seam efficiency remained below 1.2%, an extremely small value. The axial tensile strength of bonded specimens was significantly lower than that of seamless specimens, failing to fulfill long-term safety operation requirements. Therefore, bonding method should be used cautiously at non-critical structural components where the welding is impractical but repair and replacement are relatively simple. The findings provide insight for GMB installers and design engineers in order to improve the performance of HDPE GMB seams.