Not all geomembrane liners are created equal. The four major geomembrane materials -- high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), polyvinyl chloride (PVC), and reinforced polypropylene (RPP) -- each have distinct mechanical properties, chemical resistance profiles, installation characteristics, and cost structures. Selecting the wrong material for an application can result in premature failure, even if the installation is flawless.
Material selection should be driven by the specific requirements of the application: What chemicals will the liner contact? What temperatures will it experience? What mechanical loads will it bear? How long must it last? What is the subgrade condition? This guide provides the technical basis for making that selection.
HDPE: The Industry Workhorse
High-density polyethylene is the most widely used geomembrane material worldwide, accounting for approximately 60% of all geomembrane installations. Its combination of chemical resistance, mechanical strength, UV resistance, and long-term durability make it the default choice for most containment applications.
- Chemical resistance: Excellent resistance to acids, bases, and most organic solvents. Resistant to biological degradation. Vulnerable to strong oxidizers and some aromatic/chlorinated hydrocarbons.
- Mechanical properties: High tensile strength (4,000+ psi), high puncture resistance, moderate elongation at break (700-800%). Relatively stiff compared to other geomembranes.
- Temperature range: -40F to 160F for continuous service. Properties change with temperature -- stiffer and more brittle in cold, more flexible but lower strength in heat.
- UV resistance: Good with 2%+ carbon black stabilization. 20-30 year exposed service life.
- Welding: Hot wedge and extrusion welding. Well-established field welding protocols with reliable seam quality.
- Cost: $0.25-$0.60 per square foot for material, depending on thickness (40-100 mil). Most cost-effective material on a per-year-of-service basis.
- Best applications: Landfills, mining, agricultural lagoons, reservoirs, industrial containment, canal lining.
LLDPE: The Flexible Alternative
Linear low-density polyethylene shares the basic chemistry of HDPE but with a different molecular structure that provides greater flexibility and elongation. LLDPE is often chosen for applications where differential settlement, complex geometry, or field fabrication requirements make the stiffness of HDPE problematic.
- Chemical resistance: Similar to HDPE for most chemicals, but slightly lower resistance to some hydrocarbons due to lower crystallinity.
- Mechanical properties: Lower tensile strength than HDPE (2,400-3,200 psi) but significantly higher elongation at break (800-1,000%). Much more conformable to irregular subgrades.
- Temperature range: Better cold-weather performance than HDPE. Remains flexible at temperatures where HDPE becomes brittle.
- UV resistance: Good with carbon black stabilization, comparable to HDPE.
- Welding: Same methods as HDPE (hot wedge and extrusion). Welding parameters differ due to lower melt temperature.
- Cost: Similar to HDPE on a per-square-foot basis. May reduce overall project cost by reducing subgrade preparation requirements.
- Best applications: Heap leach pads with high settlement, floating covers, applications requiring high conformability, cold-climate installations.
PVC: The Specialty Material
Polyvinyl chloride geomembranes are highly flexible, easy to seam, and relatively inexpensive, making them popular for decorative ponds, aquaculture, and temporary containment. However, PVC has significant limitations that restrict its use in critical containment applications.
- Chemical resistance: Good resistance to acids, bases, and alcohols. Poor resistance to ketones, esters, and aromatic hydrocarbons. Plasticizer extraction by some chemicals reduces flexibility over time.
- Mechanical properties: Very flexible when new, but plasticizer loss causes embrittlement over time. Tensile strength lower than HDPE.
- Temperature range: Becomes brittle at low temperatures. Plasticizer migration accelerates at elevated temperatures. Service temperature limited to approximately 40F to 130F.
- UV resistance: Poor without additives. Exposed PVC degrades significantly faster than HDPE. 5-15 year exposed service life with UV stabilizers.
- Welding: Solvent welding, hot air welding, or dielectric welding. Solvent welding is fast but requires careful technique for reliable seams.
- Cost: $0.15-$0.40 per square foot. Lower initial cost but shorter service life reduces long-term value.
- Best applications: Decorative ponds, aquaculture, temporary containment, secondary containment where chemical compatibility is confirmed.
RPP: The Durable Alternative
Reinforced polypropylene is a composite material consisting of a polypropylene geomembrane reinforced with a woven or non-woven fabric scrim. The reinforcement provides superior dimensional stability, puncture resistance, and resistance to wind uplift -- making RPP an excellent choice for exposed floating cover applications.
- Chemical resistance: Excellent. Polypropylene has the broadest chemical resistance of the common geomembrane materials, with particular strength against hydrocarbons.
- Mechanical properties: Moderate tensile strength but very high tear and puncture resistance due to the reinforcement scrim. Low thermal expansion/contraction.
- Temperature range: Good performance across a wide range. Better high-temperature performance than HDPE.
- UV resistance: Excellent with proper stabilization. RPP covers have demonstrated 25+ year exposed service life.
- Welding: Hot air or hot wedge welding. Seam quality is generally excellent due to the material's dimensional stability.
- Cost: $0.50-$1.00 per square foot. Higher material cost but may be offset by longer service life in exposed applications.
- Best applications: Floating covers, exposed containment, secondary containment, temporary barriers, applications with high wind exposure.
Selection Decision Framework
For most containment applications where the liner will be buried or submerged, HDPE is the best overall choice based on its combination of performance, longevity, and cost. For applications requiring high flexibility (floating covers, settlement-prone subgrades), LLDPE or RPP should be considered. PVC is appropriate for non-critical applications where initial cost is the primary driver. RPP excels in exposed, wind-prone applications where dimensional stability and puncture resistance are paramount.
EFI USA works with all four major geomembrane materials and can provide material-specific recommendations based on your application requirements. Our engineering team evaluates chemical compatibility, mechanical loading, temperature exposure, service life requirements, and project economics to recommend the optimal material for each project. Contact us for a material selection consultation.
