Three subcommittees of ASTM International Committee D35 on Geosynthetics are currently developing several proposed new standards. The topics covered in the following proposed standards are geosynthetic clay liners, geomembranes, and the development of a mechanistic-empirical design guide for pavements.
 
Committee D35 will meet Jan. 30-Feb. 1, 2008, at the January Committee Week in Tampa, Fla. All interested parties are invited to join in the standards developing activities of D35. For membership or meeting information, contact Christine Sierk, manager, Technical Committee Operations, ASTM International (phone: 610/832-9728; csierk@astm.org).

Subcommittee D35.04 on Geosynthetic Clay Liners
 
Responding to shrinkage issues involving geosynthetic clay liners, Subcommittee D35.04 has launched work on a proposed new standard, WK12239, Test Method for Linear Dimensional Changes of Restrained Geosynthetic Clay Liners Under Cyclic Temperature and Hydration Conditions. WK12239 is an index test that covers the measurement of changes in linear dimensions of a geosynthetic clay liner that result from exposure to changes in temperature and moisture conditions over time.
 
“The proposed standard will be used to evaluate product specific and project specific potential shrinkage for GCLs exposed to changes in moisture and temperature conditions,” says Richard Erickson, D35.04 member and senior engineer, Vector Engineering, Inc. “Potential shrinkage can then be utilized by designers and construction quality assurance monitors in compensating specified GCL overlaps to allow for anticipated GCL panel shrinkage.”
 
Erickson says Subcommittee D35.04 would like to expand the circle of participants involved in the development of WK12239. All interested parties, particularly those from the design and construction quality control/assurance areas, are invited to join in the ongoing development of WK12239.

For further technical information, contact Richard Erickson, Vector Engineering, Inc., Grass Valley, Calif. (phone: 530/272-2448; erickson@vectoreng.com).

Subcommittee D35.10 on Geomembranes
 
Subcommittee D35.10 is currently developing two proposed new standards, WK14305, Specification for Non-Reinforced PVC (Polyvinyl Chloride) Geomembrane Seams, and WK14311, Guide for the Installation of Non-Reinforced Polyvinyl Chloride (PVC) Geomembranes.

According to Mark Wolschon, engineers, specification writers, users, suppliers, manufacturers, fabricators and installers of PVC geomembranes will be able to work with WK14305 hand-in-hand with D 7176, Specification for Non-Reinforced Polyvinyl Chloride (PVC) Geomembranes Used in Buried Applications, in the design and construction of commercial, municipal and residential projects. “Typical projects using PVC geomembrane are landfills, wastewater lagoons, retention ponds and decorative ponds,” says Wolschon.
 
A lack of industry consensus on how geomembrane installations should be done in the field is the impetus behind WK14311. This proposed guide would be used in conjunction with other specifications to offer engineers and contractors a reference regarding the typical conditions and minimum standard they should expect from their PVC geomembrane supplier and installer.
 
“We would like to see more participation by the rest of the PVC geomembrane industry,” says Wolschon. “We will also need to conduct round robin testing of many of the recent specifications, including D 7176, Specification for PVC Geomembrane Material, and D 7177, Specification for Air Channel Testing of PVC Geomembrane Field Seams.”
  
For further technical information, contact Mark Wolschon, Environmental Protection Inc., Mancelona, Mich. (phone: 800/655-4637; mark@geomembrane.com).

Subcommittee D35.01 on Mechanical Properties
 
There is currently a national movement to develop a mechanistic-empirical design guide for pavements. This initiative requires that the fundamental material properties for all components of the design be quantified. Subcommittee D35.01 is working toward this goal with the development of two proposed new standards, WK14361, Test Method for Determining Small-Strain Tensile Properties of Geogrids and Geotextiles by In-Air Cyclic Tension Tests, and WK14362, Test Method for Measuring Geosynthetic-Soil Interface Shear Modulus.
  
“These proposed standards will eventually be used to determine geosynthetic material properties that will be directly utilized in the design of geosynthetic-reinforced pavements when the geosynthetics are used as reinforcement of the base layer,” says Eli Cuelho, research engineer with the Western Transportation Institute and a member of D35.01. The most likely users of the proposed standards are commercial testing laboratories that will run the tests for manufacturers and designers.

For further technical information, contact Eli Cuelho, Western Transportation Institute, Montana State University, Bozeman, Mont. (phone: 406/994-7886; elic@coe.montana.edu).

Release #7708