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HDPE geomembrane is specified almost universally against GRI-GM13, the Geosynthetic Institute standard that sets minimum property values by thickness for smooth and textured sheet. This page collects the core GM13 properties, the ASTM test methods behind them, and how thickness is selected by application.
| Property | Test method | GM13 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 | 0.940 g/cc or higher |
| Tensile yield strength | ASTM D6693 Type IV | 126 lb/in width |
| Tensile break elongation | ASTM D6693 Type IV | 700 percent |
| Tear resistance | ASTM D1004 | 42 lb |
| Puncture resistance | ASTM D4833 | 108 lb |
| Stress crack resistance | ASTM D5397 (Appendix) | 500 hours |
| 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 |
| Standard OIT (oxidative induction time) | ASTM D3895 | 100 minutes or higher |
| Seam strength (field welds) | ASTM D6392 | Per GRI-GM19 shear and peel values for the sheet thickness |
| Nominal thickness | Tensile yield strength (ASTM D6693) | Tear resistance (ASTM D1004) | Puncture resistance (ASTM D4833) |
|---|---|---|---|
| 40 mil (1.0 mm) | 84 lb/in width | 28 lb | 72 lb |
| 60 mil (1.5 mm) | 126 lb/in width | 42 lb | 108 lb |
| 80 mil (2.0 mm) | 168 lb/in width | 56 lb | 144 lb |
| 100 mil (2.5 mm) | 210 lb/in width | 70 lb | 180 lb |
GRI-GM13 is the Geosynthetic Institute's standard specification for smooth and textured HDPE geomembrane. Rather than each project writing its own resin and sheet requirements from scratch, GM13 publishes minimum property values by thickness, from 30 mil through 120 mil, with the ASTM test method and testing frequency attached to each property. Nearly every North American manufacturer produces sheet certified to GM13, so citing it in a specification section gives the owner a defensible, testable baseline without naming a proprietary product.
The properties fall into three groups. Physical and mechanical properties, including thickness, density, tensile behavior, tear, and puncture, govern how the sheet survives installation and service loads. Durability properties, including oxidative induction time, oven aging, and UV resistance per GRI-GM11 exposure, govern how long the polymer resists oxidation. Manufacturing quality properties, including carbon black content and dispersion and notched constant tensile load stress crack resistance per ASTM D5397, screen out resin and extrusion problems before the sheet ever ships.
Thickness is the first line item in any HDPE section, and it is driven by application and regulation more than by structural calculation. A 40 mil sheet is common for lighter-duty ponds, decorative water features, and short-term containment where subgrade is well prepared and traffic over the liner is limited. It welds faster and costs less, but it tolerates less abuse during placement.
The 60 mil sheet is the industry workhorse. Municipal solid waste landfill designs under RCRA Subtitle D commonly specify 60 mil HDPE as the geomembrane component of the composite liner, and most secondary containment, heap leach, and wastewater applications land here as well. It balances weldability, puncture resistance, and stress crack performance, and it is the thickness with the deepest supply and installer familiarity.
The 80 and 100 mil sheets appear where loads, service life, or exposure justify them: deep landfill cells with high overburden, coarse or aggressive subgrades, exposed liners that will see decades of thermal cycling, and caps or ponds subject to equipment traffic. Thicker sheet resists puncture and tear roughly in proportion to thickness, as the scaling table above shows, but it is stiffer, slower to deploy, and demands more from the welding crew. The project specification and the governing regulation always control; when a permit names a thickness, that is the floor.
GM13 publishes parallel property tables for smooth and textured HDPE. Smooth sheet is the default on floors, flat grades, and gentle slopes where interface shear strength does not control the design. Textured sheet carries a roughened surface, produced by coextrusion or structuring, that raises the interface friction angle against soils, geotextiles, and geosynthetic clay liners.
Texturing is specified when a veneer stability analysis says the smooth interface cannot hold the slope: landfill side slopes, lined channel banks, and any composite section where a cover soil or drainage layer sits on the geomembrane on grade. Sheet is available textured on one side or both, so a designer can place the textured face against the critical interface. The tradeoffs are real but manageable: textured sheet has lower break elongation than smooth sheet of the same thickness, texturing adds cost, and asperity height, verified per ASTM D7466, becomes one more conformance property to check on delivery.
A complete HDPE geomembrane submittal package pairs the manufacturer's product data sheet with roll-specific quality control certificates. The data sheet states conformance to GM13 for the specified thickness and surface. The QC certificates report actual test results by roll or resin lot for thickness per ASTM D5199, density per ASTM D1505 or D792, tensile properties per ASTM D6693, tear per ASTM D1004, puncture per ASTM D4833, carbon black content per ASTM D4218, carbon black dispersion per ASTM D5596, and standard OIT per ASTM D3895, with stress crack resistance per ASTM D5397 reported per resin formulation.
On the installation side, the submittal adds welder qualifications, proposed seam layout, trial weld procedures, and the field seam testing plan: nondestructive testing of every seam by air pressure or vacuum box, plus destructive samples tested in shear and peel per ASTM D6392 at the frequency the specification sets. Reviewing this package line by line against the specification is the cheapest quality control a project ever buys.
Field seams are governed by GRI-GM19, the companion standard to GM13, which sets minimum shear and peel values by sheet thickness and weld type. For 60 mil HDPE, GM19 requires 120 lb/in in shear for both weld types, with peel minimums of 91 lb/in for hot wedge fusion welds and 78 lb/in for extrusion fillet welds. Destructive samples are tested per ASTM D6392, and specimens must also meet a film tear bond criterion, meaning the failure occurs in the sheet rather than by separation through the weld itself. Fusion welding with a dual-track wedge is the production method for long panel seams because the air channel between tracks allows every seam to be pressure tested; extrusion welding handles details, patches, and penetrations.
Single and composite-lined cells, caps, and leachate ponds for MSW, hazardous, and coal-ash sites.
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