LLDPE Geomembrane Specifications
GRI-GM17 specifies manufacturing quality-control properties for smooth and textured linear low-density polyethylene geomembranes. Its tables distinguish sheet thickness and surface finish. LLDPE flexibility can be useful where deformation matters; product selection still depends on the containment chemistry, predicted movement and supporting design.
Material properties and test methods
| Property | Test method | GM17 requirement (60 mil smooth) |
|---|---|---|
| Thickness (minimum average) | ASTM D5199 | 60 mil nominal (1.5 mm), lowest individual reading not less than 10 percent below nominal |
| Density | ASTM D1505 / D792 | 0.939 g/cc or lower |
| Tensile break strength | ASTM D6693 Type IV | 228 lb/in width |
| Tensile break elongation | ASTM D6693 Type IV | 800 percent |
| 2 percent modulus (maximum) | ASTM D5323 | 60,000 psi (414 MPa) maximum |
| Tear resistance | ASTM D1004 | 33 lb |
| Puncture resistance | ASTM D4833 | 84 lb |
| Axi-symmetric break resistance strain | ASTM D5617 | 30 percent minimum |
| Carbon black content | ASTM D4218 | 2.0 to 3.0 percent |
| Carbon black dispersion | ASTM D5596 | Category 1 or 2 for at least 9 of 10 views |
| Initial oxidative induction time (OIT) | ASTM D8117 or D5885 | Standard OIT: 100 minutes minimum; or high-pressure OIT: 400 minutes minimum, at the manufacturer’s option |
| Nominal thickness | Tensile break strength (ASTM D6693) | Tear resistance (ASTM D1004) | Puncture resistance (ASTM D4833) |
|---|---|---|---|
| 40 mil (1.0 mm) | 152 lb/in width | 22 lb | 56 lb |
| 60 mil (1.5 mm) | 228 lb/in width | 33 lb | 84 lb |
| 80 mil (2.0 mm) | 304 lb/in width | 44 lb | 112 lb |
| 100 mil (2.5 mm) | 380 lb/in width | 55 lb | 140 lb |
What GRI-GM17 covers and how it differs from GM13
GRI-GM17 is the Geosynthetic Institute's standard specification for smooth and textured linear low density polyethylene geomembrane, the direct counterpart to GRI-GM13 for HDPE. Like GM13, it publishes minimum property values by thickness with the ASTM test method and testing frequency attached to each property, so a specifier can cite one document instead of writing resin and sheet requirements from scratch.
The differences between the two standards describe the differences between the two materials. GM17 caps density at 0.939 g/cc where GM13 sets a floor at 0.940 g/cc, because lower crystallinity is what makes LLDPE flexible. For smooth sheet, GM17 requires 800 percent break elongation against GM13's 700 percent; the textured-sheet minimums are 250 and 100 percent respectively. GM17 also adds a 2 percent modulus ceiling so a stiff sheet cannot be sold as LLDPE, and requires a 30 percent minimum axi-symmetric break strain per ASTM D5617, a multiaxial test GM13 does not include. In exchange, GM17 drops the notched constant tensile load stress crack requirement, because stress cracking is a high-crystallinity failure mode that LLDPE resists by nature.
Why flexibility is the property being purchased
LLDPE is selected when the design expects the liner to deform. ASTM D5617 measures axi-symmetric break strain, with a 30 percent minimum in GM17. This laboratory index value is not an allowable field strain. The design must account for settlement, support conditions, seams and connections for the selected product.
Review compatibility for the proposed product and the actual liquid composition, concentration, temperature and exposure duration. GM17 conformance does not establish chemical suitability for every application. Evaluate the supplier’s supporting data with the design team before selecting HDPE or LLDPE.
Selecting thickness and where LLDPE is used
GM17 includes thicknesses from 20 through 120 mil. Select thickness against the project specification, permit, support conditions, loads and proposed installation. Thickness must be evaluated as part of the complete liner design.
Where settlement or subgrade movement drives the design, review whether the proposed LLDPE product can accommodate the predicted deformation. For slopes, confirm interface shear properties for the actual combination of geomembrane, soil and adjacent geosynthetics; the smooth or textured designation is insufficient for a stability assessment.
Field seaming and QA for LLDPE
LLDPE welds with the same equipment and procedures as HDPE: dual-track hot wedge fusion for long panel seams and extrusion fillet welding for details, patches, and penetrations. Seam minimums come from GRI-GM19a, which publishes shear and peel values for LLDPE by sheet thickness and weld type, slightly lower than the HDPE values at the same thickness in keeping with the softer sheet.
The approved field testing plan identifies nondestructive methods, coverage and acceptance criteria, including air-channel testing per ASTM D5820 or vacuum-box testing per ASTM D5641 where applicable. Destructive samples are cut at the specified frequency and tested per ASTM D6392. Evaluate seam strength, shear elongation, peel separation and acceptable break patterns against GRI-GM19a for the material, thickness and weld type, together with the approved project criteria.
What appears on an LLDPE submittal
A complete LLDPE submittal pairs the manufacturer's product data sheet, stating conformance to GM17 for the specified thickness and surface, with roll-specific quality control certificates reporting thickness per ASTM D5199, density per ASTM D1505 or D792, tensile properties per ASTM D6693, tear per ASTM D1004, puncture per ASTM D4833, axi-symmetric strain per ASTM D5617, carbon black content and dispersion per ASTM D4218 and D5596, and standard OIT per ASTM D8117 (100 minutes minimum) or high-pressure OIT per ASTM D5885 (400 minutes minimum), with the manufacturer selecting either listed method.
The installation submittal adds welder qualifications, the proposed panel and seam layout, trial weld procedures, and the field seam testing plan. Confirm that the proposed sheet meets the specified GM17 density limit and the other required properties. Check strain capacity against the complete material specification.
Primary sources and review date
References checked September 23, 2026: GRI-GM17 revision 17 (June 11, 2025), GRI-GM13 revision 19 (June 11, 2025), and GRI-GM19a revision 10 (March 18, 2021). GM17 is a manufacturing quality-control specification. Confirm the edition and any additional requirements in the project specification.
We install this material
Heap-leach pads, tailings impoundments, solution channels, and evaporation ponds.
Frequently asked questions
Need a submittal package or spec match?
Send us your project specification and we will match materials, assemble submittal data, and scope the installation.