Report from the North American Geosynthetics Society (NAGS)

April 1, 2015

By Bob Mackey ASTM Committee D35 on Geosynthetics The ASTM Committee D35 on Geosynthetics met in New Orleans, La., Jan. 28–30, 2015. There was significant progress within several of the D35 subcommittees as noted here: Subcommittee D35.03 on Permeability and Filtration The issue that generated a great deal of discussion at the January meeting of …

Allowable stress on geonets based on laboratory creep tests

October 1, 2014

By Dhani Narejo and Sam Allen Introduction The first article in this three-part series presented compressive stress-strain behavior of several different geonet structures. The collapse, or rollover, does not occur for many types of geonets. In the absence of a rollover, the compression of geonets is non-linear in most cases with the compression rate being …

Allowable stress on geonets based on laboratory creep tests

August 1, 2014

By Dhani Narejo and Sam Allen Introduction This article focuses on biplanar geonets to the extent of the possible tendency for the two sets of integrally joined ribs to roll over on one another while load is applied. The significance of such a rollover is a reduced transmissivity value as compared to that obtained from …

Geosynthetics committee examines drainage issues

July 17, 2014

Proposed ASTM standard for stormwater catch basin filters. ASTM International in a July 17 press release announced a proposed new standard that will offer a means to reduce the impact of contaminated stormwater entering local drains. WK45326, Specification for Stormwater Catch Basin Filter, will aid community developments, sports facilities, fairgrounds, stadiums, and factories in complying …

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The influence of soil type on interface behavior under pullout conditions

June 1, 2014

Part 3: European experience in pullout tests By Nicola Moraci, Daniele Cazzuffi, Lidia Sarah Calvarano, Giuseppe Cardile, Domenico Gioffrè, and Piergiorgio Recalcati 1. Introduction The rapid increasing application of geosynthetics as reinforcement elements for earth structures requires a careful examination of soil-reinforcement interaction mechanisms. The soil-geosynthetic interaction can be complex because it is affected by …

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Geonet structure, short-term stress/strain behavior, and creep test methods

Part 1: Allowable stress on geonets By Dhani Narejo and Sam Allen Introduction Several types of geonets are used in numerous applications worldwide. Examples of the types of geonets include biplanar, triplanar, spiked or profiled, cuspated, tubular, and three-dimensional (3-D) filament meshes (see Figure 1 and Table 1). Common and emerging applications for these materials …

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Air-channel testing of thermally bonded flexible polypropylene geomembrane seams

April 1, 2013

By Timothy D. Stark, Richard W. Thomas, and Thomas J. Dehlinl Introduction For more than a decade, thermal welding has proven to be an efficient and cost-effective procedure for field-seaming geomembranes. Thermal welding of polyvinyl chloride (PVC) geomembranes has allowed use of air-channel tests in lieu of destructive peel tests to verify field seams meet …

ASTM D6637–11 standard test method

November 10, 2011

The determination of the tensile force-elongation values of geogrids provides index property values. This test method is used for quality control and acceptance testing of commercial shipments of geogrids. In cases of dispute arising from differences in reported test results when using this test method for acceptance testing of commercial shipments, the purchaser and supplier …

ASTM D7747–11 standard test method

The use of reinforced geomembranes as barrier materials has created a need for a standard test method to evaluate the quality of seams produced by thermo-fusion methods. This test method is used for quality control purposes and is intended to provide quality control and quality assurance personnel with data to evaluate seam quality. This standard …

New ASTM geosynthetic practice standardizes leak-detection method

A new ASTM International practice standardizes a geoelectric method used to detect potential leaks in exposed electrically isolating membranes in the field in containment applications. The new standard, ASTM D7703, Practice for Electrical Leak Location on Exposed Geomembranes Using the Water Lance System, is under the jurisdiction of Subcommittee D35.10 on Geomembranes, part of ASTM …