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GSI/GRI-GG5 and ASTM D6706

October 7, 2009

GMA techline answers from Bob Koerner Subject: GG5 I referenced GSI/GRI–GG5 on a segmented retaining wall system spec and need to know if this is correct. Supposedly on your website this standard was crossed out and noted to refer to ASTM D6706. Should I replace GG5 with the ASTM standard? Please clarify. (Rebecca, New Jersey) …

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The difference between strength parameters

June 1, 2009

By Timothy D. Stark Q: What is the difference between the strength parameters c and ø, and a and δ? A: Good question because these parameters are frequently used interchangeably. c and ø, and a and δ are shear strength parameters used to represent the strength/failure envelope for a particular material. The strength envelope is …

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Comparing specs

April 1, 2009

GMA techline answers from Bob Koerner Subject: Comparing specs — I want to know how can I compare specification values of ASTM with ISO?? I sell products tested with ASTM methods, but some clients give me an ISO specification. I want to know which product fits their requirements. (Claudia, Mexico) Reply: You ask an excellent …

New ASTM standard for EPDM sheet material

February 1, 2009

A new ASTM standard developed by ASTM International Committee D35 on Geosynthetics fills a need for an internationally recognized standard to ensure that EPDM sheet material received by customers is consistent regardless of the manufacturer. The new standard, D7465, Specification for Ethylene Propylene Diene Terpolymer (EPDM) Sheet Used in Geomembrane Applications, is under the jurisdiction …

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Break/yield strengths

October 1, 2008

From the GMA Techline Subject: Break/yield strength —I am a structural engineer working in Chile. I used the following text from your organization: GM13, GM17, and GM19. About GM13 (Rev.8: July 10, 2006), page 10 from this text shows yield strength and break strength for HDPE geomembrane-textured. The table 2b shows yield strength > break …

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Drainage geocomposite

From the GMA Techline Subject: Drainage geocomposite— I have to test drainage geocomposite material regarding friction behavior and internal shear strength. In terms of references, I see 2 options: friction test (drain material/soil), according to ASTM D5321; and internal shear strength, according to ASTM D5321. I know that for friction test of drainage material, it …

How long will my liner last?

What is the remaining service life of my HDPE geomembrane? By Ian D. Peggs, P.E., P.Eng., Ph.D. Introduction In his keynote lecture at the GeoAmericas-2008 conference last March, Dr. Robert Koerner (et al., 2008) of the Geosynthetic Institute (GSI) reported the ongoing Geosynthetic Research Institute (GRI) work to make the first real stab at assessing …

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Geotextiles in dams: Forging federal guidelines

August 1, 2008

By Douglas A. Crum Abstract The major building era for large dams in the United States, from the 1940s to the 1970s, ended about the time geotextiles were becoming popular. For the last 40-plus years, geotextiles have been used in many dams worldwide for various applications. During this period, federal agencies have resisted experimentation with …

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Active LFG control: An unreliable aid to veneer stability

June 1, 2008

By Gregory N. Richardson, Stacey A. Smith, and Pieter K. Scheer Abstract The potential for sliding failure of final covers and piggyback liners in municipal solid waste (MSW) landfills equipped with active landfill gas (LFG) control systems is demonstrated and the need for a contingency passive venting system is presented. Two final cover failures illustrate …

Celebrating a decade of GSI/GRI polyolefin specs

By Bob Koerner From the very beginning of the GSI/ GRI consortium in 1986, it was recognized that specific focus groups were the way to initiate individual programs and documents. After a draft document is eventually established within a group, the entire membership is then brought into the activity for modification and eventual agreement. This …