By Bob Koerner
In the 1980s, while supervising graduate research students in their geosynthetics theses topics, the issue of writing generic and standardized procedures arose in this (quite new at the time) geosynthetics field. Rob Swan generated our first formalized test methods with what became GRI-GG1: “Geogrid Rib Tensile Strength” (now ASTM D6637) and GRI-GG2: “Individual Geogrid Junction Strength.”
Through the subsequent years many more standards were promulgated by students and mainly by Drs. George Koerner and Grace Hsuan. A good percentage of these standards (29%) were subsequently adopted in whole or part by ASTM.
We made the decision to group our GRI standards by geosynthetic type rather than application area and continue to do so. Please note that we continue to use the GRI (Geosynthetic Research Institute) designation since all of our standards have in-house research and development testing involved in their development. The following table lists our current standards, which include specifications, guides, practices, and test methods.
The specifications, guides, and practices are registered under U.S. copyright and are also available free via the GSI Home Page, www.geosynthetic-institute.org. It is the latest version that is always online. The test methods are available at a nominal price. The entire collection of 54 GRI Standards are available for $100 plus shipping and handling. Commentary on some of the newer standards follows:
- Geotextile tubes for erosion control, dewatering, and now decontamination of polluted river and harbor sediments are a growing application area. We have available the modification of Jack Fowler’s original concept of a “hanging bag” test for assessing if a given fabric type is suitable for a given dredged soil type. It is available as the GRI-GT14 test method.
- Biaxial geogrids are used for roadway and airfield stabilization and one potential test method to assess their performance is the “torsional rigidity” test when subjected to in-plane rotation. It is a modification of Dr. Tom Kinney’s original test and is available as the GRI-GG9 test method.
- “Temporary landfill covers” are used to prevent or retard landfill gasses from release into the atmosphere. Cost-wise, however, a thick permanent geomembrane is not warranted for a relatively short 5-10 year lifetime. Thus a specification for lightly reinforced polyethylene geomembranes is available. It is GRI-GM22 and addresses properties for three different thicknesses.
- GCL testing is known to be difficult insofar as gripping the upper and lower geotextile surfaces in a large direct shear box. Borrowing from Dr. Pat Fox’s research, we have used his “end platens” in our GRI-GCL4 test method. It is currently available with photos and graphic details.
- Another new GCL standard is a practice for taking “undisturbed field samples” for subsequent hydraulic conductivity testing. Developed by Dr. George Koerner, it is designated as GRI-GCL5.
- In the geocomposite area, we have two recent test methods both directed toward “geosynthetic (geofoam) gravel.” They were developed by George Koerner. One test method is focused on mechanical deformation behavior, the other on hydraulic behavior. They are designated GRI-GC9 and GRI-GC10, respectively. They are currently undre consideration by ASTM for possible adoption.
Needless to say, as time progresses please look for new standards to be developed by GRI in all geosynthetic areas. It is exciting for us to be key players in the important process of advancing the industry through standardization.