Geosynthetics (GTX & REGEO)

Geosynthetics are materials manufactured from various types of polymers used to enhance, augment, and make possible cost-effective environmental, transportation, and geotechnical engineering construction projects. They are used to provide one or more of the following functions: separation, reinforcement, filtration, drainage, and liquid barrier.

Geotextiles are typically defined as flexible, textile-like fabrics of controlled permeability used to provide all of the above functions, except liquid barrier, in soil, rock, and waste materials. It should be noted that natural fiber geotextiles (e.g. using jute) are manufactured in some parts of the world and these products are also considered to fall within the geotextile classification.

NTPEP is also studying the use of geocomposite drains and geogrids. Geogrids are generally described as stiff or flexible polymer grid-like sheets with large apertures used primarily as reinforcement of unstable soil (and waste masses.)

The growth of these geosynthetic materials in Transportation, Geotechnical, and Environmental related applications has been dramatic. Total use and sales of these materials are regularly increasing at rates of 10% to 20% per year in each of the above categories. (Source: International Geosynthetics Society, IGS)

The GTX and REGEO work plans can be found by clicking on Documents in the right side menu.

NTPEP Designated Lab:

  • GTX: TRI/Environmental, Inc.
  • REGEO: ​TRI/Environmental, Inc.

Participating Geotextile Manufacturers​

A list of participating Geotextile manufacturers with a quality management system found to conform to the NTPEP GTX work plan.​​

NTPEP - Geosynthetics

Committee Name:
NTPEP-Technical Committee on Geotextiles and Geosynthetics
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GTX Work Plan

REGEO Work Plan

SSGEO Work Plan

Please go to NTPEP DataMine.

Please go to NTPEP DataMine.


Geotextiles (GTX)


  • This is a testing and audit program
  • Testing is based on AASHTO M 288 “Standard Specification for Geotextile Specification for Highway ”
  • Individual products are retested every 3
  • Audits are conducted annually.
  • The audit program requires that manufacturers provide product marking directly on the fabric and labeling on the
  • The audit program verifies that manufacturing plants, private label companies, and converters conform to the quality assurance requirements of the GTX work

GTX Testing

  • ASTM D5261, “Standard Test Method for Measuring Mass per Unit Area of ”
  • ASTM D4632, “Standard Test Method for Grab Breaking Load and elongation of Geotextiles.”
  • ASTM D4533, “Standard Test Method for Trapezoid Tearing Strength of ”
  • ASTM D4491, “Standard Test Methods for Water Permeability of Geotextiles by Permittivity.”
  • ASTM D6241, “Standard Test Method to Determine Asphalt Retention of Paving Fabrics Used in Asphalt Paving for Full-Width Applications”
  • ASTM D4751, “Standard Test Method for Determining Apparent Opening Size of Geotextile”
  • ASTM D4355, “Standard Test Method for Deterioration of Geotextiles by Exposure to Ultraviolet Light and Water (Xenon-Arc Type Apparatus)”
  • Test results for each product are provided in table form for easy comparison to AASHTO M 288 and your state

GTX Audits

  • Audits follow the NTPEP “Standard Practice for Qualification of Highway Product Manufacturers Through the Use of NTPEP ”
  • Products must be marked and
    • Markings must be clearly printed along the edge of the product roll at least once every 5 meters.
    • The marking shall be a NTPEP established identifier that is unique to each manufacturer and
    • Labels must be affixed to both ends of the outer product wrapping and at the roll core. Labels must state roll number, production date, AASHTO M 288 class, and the product
  • Private Labelers
    • Products must come from a compliant NTPEP audited
    • Products must be traceable to an audited, NTPEP compliant source
    • The source manufacturer must print the private label information on the rolls and labels.
  • Geotextile Converters
    • Converters modify a geotextile that has been obtained from another manufacturer to produce a finished product that is different from the source product.
    • Converters must re-label rolls and may reprint a new code or name on The new code or name must match the new labels.
  • Audit reports and test results can be found in



Additional information on this evaluation can be found at:

AASHTO National Transportation Product Evaluation Program (NTPEP)



Success Stories

Glenn Roberts, PE

Geotechnical Chief

New Hampshire DOT

In 2003 the New Hampshire Department of Transportation (NHDOT) implemented a new standard specification for geotextiles requiring prequalification of products based solely on NTPEP test data.  Prior to that time, products were listed based on manufacturer-supplied minimum average roll values.   Use of the NTPEP test data has provided the Department with a credible, consistent source of qualified products for use on NHDOT construction projects with minimal demand on limited in-house resources.

Sample Specifications

  • New Hampshire DOT Geotextile Qualification Criteria
  • New Hampshire DOT specification for Geotextiles
  • Washington DOT material spec for geotextiles
  • Washington DOT spec for geotextiles
  • Indiana spec for geotextiles
  • North Carolina spec for geosynthetics
  • North Dakota GTX spec