Maximum slope angle for geosynthetic-lined slopes

June 1, 2009  |  Q&A: GMA Techline

By Timothy D. Stark Q: Is there a maximum slope angle for geosynthetic-lined slopes? A: Yes there is, and the slope angle should not exceed the lowest geosynthetic interface friction angle, δ, of the system. The slope angle should not exceed δ because this condition can/will lead to tens…
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Geomembranes and reservoirs

June 1, 2009  |  Q&A: GMA Techline

By Timothy D. Stark Q: Is it possible to cover an entire reservoir with a geomembrane? In addition, is it possible to line an entire reservoir or lake with a geomembrane? A: The answer is yes to both questions. Geomembranes are frequently used to cover reservoirs, especially in California (USA) for …
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Testing seams

April 1, 2009  |  Q&A: GMA Techline

From the GMA Techline Subject: Testing — What methods are available to test seams on HDPE and EPDM to ensure quality of joins in the field that should be part of the installation quality assurance? (Masson, New Zealand) Reply: You ask an interesting question in that HDPE is a thermoplastic pol…
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Comparing warp and fill

April 1, 2009  |  Q&A: GMA Techline

From the GMA Techline Subject: Warp and fill — What do the terms warp and fill mean with regard to tear strength of a polypropylene liner? (Michael, Alaska) Reply: You ask a fair question that has a simple and difficult answer to it. The simple one is that the polypropylene membrane you are us…
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Comparing specs

April 1, 2009  |  News, Q&A: GMA Techline

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, Mex…
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Study on pH and geogrids

April 1, 2009  |  Q&A: GMA Techline

From the GMA Techline Subject: pH and geogrids — I read your Techline section in Geosynthetics magazine and I find it excellent. In the October/November 2008 issue, you mentioned having a study on pH and geogrids in masonry segmental units. If possible, I would like to get a copy of that. (Gab…
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Technical articles on geosynthetics

April 1, 2009  |  Q&A: GMA Techline

From the GMA Techline Subject: Student advice — I am a student in my final year in civil engineering. I have decided to do my final year project on geosynthetics for which I need some information. I would like to know about some of the testing methods that could be adopted to prove the charact…
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Teaching geosynthetics

October 1, 2008  |  Q&A: GMA Techline

From the GMA Techline Subject: Teaching geosynthetics— I am wondering if you have a list of universities that teach at least one full-time course in geosynthetics. Thank you. (Craig, Pennsylvania) Reply: You have come to the right place! As the author of the only textbook on geosynthetics, I k…
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GMA Techline’s first 500 Q’s-and-A’s

August 1, 2008  |  Q&A: GMA Techline

By Bob Koerner and Andrew Aho Introduction The Geosynthetic Materials Association (GMA) introduced the GMA Techline on Aug. 31, 2004, as a service to those involved with, and interested in, geosynthetics. The Techline is one of the educational services offered by GMA, with the goal of providing fast…
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GRI Standards

April 1, 2008  |  News, Q&A: GMA Techline

From the GMA Techline Subject: GRI Standards — I am seeing references to GRI Standards GM 10, GM 14, and GM 18 in a project spec for a facility that will be under construction soon. There are other references too, of course, but these I’ve listed are not current, according to your Web si…
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