Title: Rating Geomembranes


Rating Guide

This Tech Note describes a geomembrane selection method based on the physical properties of the materials.

There is such a wide selection of geomembranes available that it is often difficult to identify which geomembrane has the properties required for an application. At the 6th International Conference on Geomembranes, Peggs and Thiel (1998) proposed a method for selecting geomembranes based on material properties. This Tech Note describes how this method has been further developed for Layfield’s geomembrane products.

In the paper by Peggs and Thiel the geomembrane ratings were assigned in a subjective manner based on the experience of the specifier. Layfield has taken that approach further by starting with the physical material properties, and then adjusting the ratings based on our experience. Additonal subjective ratings are applied N/R where numeric results were not clearly available.

Each geomembrane property is rated on a common scale and then assigned a letter. The letters are; A - the best solution for that application; B - a good solution for that application; M - may be suitable for that application, discuss with your Layfield representative; a listing of N/R means that the material is not recommended.

There are three basic categories of applications: properties required for backfilled geomembranes; properties required for exposed geomembranes; and properties required for installation.

Properties Required for Backfilled Geomembranes

There are three key properties required for a backfilled geomembrane. Interface friction angles are available for most materials. We used a range of friction angles from a low of 18 degrees for HDPE to a high of 26 degrees for textured HDPE. A high friction angle allows for steeper slope construction which can optimize pond (containment) volumes.

Resistance to backfilling requires a combination of strength and puncture resistance. To develop this number we combined tensile strength with “survivability” (see the section on installation properties). A value of M in this rating means that backfilling should proceed with the utmost care.

Resistance to settlement is dependant on the elongation properties of a material. The usable elongation is either the yield point, or an interpreted percentage of the available elongation based on Layfield testing. Settlement is common in landfill caps, or in areas where settlement is expected in the sub-base after construction.

Properties Required for Exposed Geomembranes

There are four properties required for exposed geomembranes. Ultraviolet light resistance (UV Resistance) is a basic requirement for all exposed geomembranes. The values used for this rating are based on the experience of Layfield as to the longevity of geomembranes in a specific geographic area.

Low temperature resistance is a measured property of a geomembrane, however, there are many contradictory test methods. Layfield has estimated the low temperature performance of geomembranes on the same scale of measurement based on internal comparative tests. Although Layfield recommends that all geomembranes should be backfilled for optimum performance, materials with an M rating should usually be backfilled for protection. Low temperature handling properties of a geomembrane may vary from the actual cold temperature resistance.

Resistance to mechanical damage is based on the tensile strength of a material. Layfield has developed a comparative scale so that material strengths, tested by different test methods, can be compared. Materials with low resistance to mechanical damage should be backfilled for protection.

The last property for exposed liners is dimensional stability. This is important when geomembranes are placed on steep slopes. Materials with poor dimensional stability could be subject to creep and could fail on steep slopes. As a starting point to determine dimensional stability we modified the strength of a material by its elongation properties.

Installation Properties

Often the key to geomembrane selection is whether or not the material can be installed in the required application. There are four rated properties for installation. Ease of mechanical attachment is related to the thickness and stiffness of a material. The ratings shown are based on Layfield’s experience. Certain materials are very difficult to attach to structures and pipes which limits their application.

Detail weldability is related to the method of welding and the equipment required to perform the weld. Solvent welds and glues are the most versatile, followed by hot air weldable, and then extrusion weldable materials. Multiple pipe penetrations are best lined with materials that have excellent detail weldability. Conversely a material with low detail weldability should not be used in a pond with extensive penetrations or mechanical attachments.

Installation survivability refers to the condition of the subgrade at installation. The ratings are based on the published values of truncated cone puncture tests (Hullings, Koerner, 1991), as well as testing performed by Layfield. Certain materials are very sensitive to poor subgrades and this rating identifies these materials.

Finally cold weather weldability is rated based on Layfield’s experience in welding materials in cold weather. Often an installation cannot go ahead with the material specified due to winter, or other adverse weather conditions. Please note that there is no material that can be welded in wet conditions, this rating is strictly for cold temperature welding.

Geomembrane Rating Guides

In the geomembrane specifications booklet each material contains a Rating Guide chart. The properties on the charts are rated A, B, M, or N/R. The example chart below shows Layfield’s Arctic Liner (AL) material in styles 30 and 38. The ratings allow us to make some intepretations about the material’s performance as a liner. The chart shows that the AL30(U) material is ideal for backfilled applications while the AL38(S) material is more suited for exposed use.

Layfield’s Geomembrane Selection Guide

The ratings shown are also contained in the Layfield Geomembrane Selection Guide. This guide calculates the most suitable geomembrane for you application. The Layfield Geomembrane Specification Guide is available from your representative or it can be downloaded from our web site at www.geomembranes.com. The selection guide on our web site is updated periodically to reflect new material properties.

The geomembrane selection guide allows you to rate the properties that you feel are most appropriate to your project. The project properties are then cross multiplied with numerical material ratings to provide a weighted rating for each material. Its very interesting to see how materials that you never considered before can become excellent candidates for your next project.


Peggs, I.D., Thiel, R., (1998), “Selecting a Geomembrane Material,” Proceedings of the Sixth International Conference on Geosynthetics, IFAI, St. Paul, MN. pp 381-388.

Hullings, D., Koerner, R., (1991), “Puncture Resistance of Geomembranes Using a Truncated Cone Test,” Proceedings of Geosynthetics ‘91, IFAI, St. Paul, MN. pp 273-285



7 Jan 2002 Layfield Geomembrane Rating Guide for Arctic Liner ®
Style Backfilled Exposed Installation
Interface Friction Resistance to Backfilling Resistance to Settlement UV Light Resistance Low Temp Resistance Mech. Damage Resistance Dimensional Stability Ease of Mech. Attachment Detail Weldability Installation Survivability Cold Weather Weldability
AL 30® (U) A B A B M M M A A A A
AL 38® (S) M M M A B B B A A M A
A best choice for this application
B good choice for this application
M may be suitable for this application. Please contact Layfield.

Ratings are based on material properties interpolated by Layfield. Ratings described in the Rating Guide Tech Note. Final evaluation of suitable physical properties is the responsibility of the user.