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The ASTM D35 Committee on Geosynthetics met in Norfolk, Va., February 1–3, 2017. Among the topics addressed were these three subcommittee reports.
Under ASTM D35.01 Subcommittee on Mechanical Properties, a task group is working to develop a protocol for biaxial testing of geosynthetics. This test would describe the tensile properties of the geosynthetic as it is pulled simultaneously in two directions. It is hoped information from this test will be used in a model to design geosynthetic-reinforced pavements. For more information, contact Eli Cuelho, elic@montana.edu
ASTM D35.04 Subcommittee on Geosynthetic Clay Liners is embarking on an effort to develop a standard guide for polymer amended bentonites. Several volunteer laboratories will conduct tests on amended bentonites to see if the same tests used for standard bentonites will be valid or if a new set of tests will need to be developed. In addition, a new guide for installation damage of GCLs is being developed. Further a round-robin is in progress to improve the Fluid Loss Test ASTM D5891. Comments on the recent ballot on the Free Swell Test ASTM D5890 were discussed and changes were made. The standard will be re-ballotted.
ASTM D35.05 Subcommittee on Geosynthetics in Erosion and Sediment Control continues to spend significant time enhancing basic index test methods for rolled erosion control products (RECPs). Recently, thickness, mass per area, and tensile strength have been approved with important clarifications, as have compression, resiliency, and stiffness. One index test method, light penetration, is requiring a much greater refinement effort as it has been found that the method works better for some product types than for others. Some new standards are under development in the subcommittee. A flexural strength test method has been developed for a new class of materials—geosynthetic cementitious composite mats (GCCMs)—that are used for channel linings; a new tensile strength test is under development for ground anchors used with turf reinforcement mats; and a new specification for turf reinforcement mats has been introduced.
–reported by Bob Mackey
For more information:
Katerina Koperna—ASTM D35 Committee, staff representative, kkoperna@astm.org
Jim Goddard—ASTM D35 Committee chairman, jimgoddard3@gmail.com