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Finite element method (FEM) update
February 1st, 2014
 Geonet anisotropy and its effect on the planar flow in drainage geocomposites. By Dhani Narejo Anisotropy is the characteristic of a material having different values for a property when measured in different directions. Materials can be anisotropic with respect to their physical, mechanical, electrical, hydraulic, and many other types of properties. Anisotropy results from […]
Allowable construction loading on geosynthetics
February 1st, 2014
From the GMA Techline RE: Allowable construction loading on geosynthetics Hello Dr. Koerner, On the question of allowable construction loading on geosynthetics, Daniel and Koerner (2007) state: “If not specifically excluded in the regulations, and if agreed on by the CQA engineer, all-terrain vehicles (ATVs) or equipment with smooth, oversized tires of maximum ground contact […]
Geomembrane UV protection?
February 1st, 2014
From the GMA Techline RE: Geomembrane UV protection? I have a question regarding geomembranes and I hope you can help. If a geotextile is placed over a geomembrane, is that considered sufficient to provide long-term UV protection for the geomembrane? Any input is greatly appreciated. Thank you, (Walter | Pennsylvania) Reply: It’s good to hear […]
Cover veneer stability and freezing
February 1st, 2014
From the GMA Techline RE: Cover veneer stability and freezing I received a question recently from a regulator on whether freezing conditions could result in reduced interface shear strength between a geocomposite drainage layer and a geomembrane for a cover system with three feet of overlying soil. We have not historically seen freezing and ice […]
NCMA’s Design Manual for Segmental Retaining Walls
February 1st, 2014
Submittal requirements for polyester geogrid reinforcement By R. Lance Carter and Michael Bernardi Adopted by the NCMA Segmental Retaining Wall & Hardscape Products Committee Editor’s note Lance Carter and Michael Bernardi, although competitors, felt the need to remind geosynthetic users, specifiers, and designers that as manufacturers and marketers of polyester reinforcement products, they are held […]
More silt fence
February 1st, 2014
From the GMA Techline RE: More silt fence Also, I have another question regarding geo properties and their specifications. Permittivity is an indicator of how well water can flow through the fabric. AOS is an indicator of the soil particle size held back by the fabric. The permittivity specification is a minimum value while AOS […]
Silt fence
February 1st, 2014
GMA techline answers from Bob Koerner RE: Silt fence I have read M288 and understand the different levels of material specifications for highway applications. Is there another category that can be sold to the public that does not have to meet the specifications for highway applications? For example, a home gardening category that can be […]
Apparent opening size (ASTM D4751) for geotextiles
February 1st, 2014
From the GMA Techline RE: Apparent opening size (ASTM D4751) for geotextiles Our specification calls for a geotextile with an AOS of #50 U.S. sieve (0.3mm). I understand that unlike the rest of the technical property values, AOS is specified by the maximum value (i.e., MaxARV not MARV). Please advise. Does it mean that I […]
Road stabilizers
February 1st, 2014
From the GMA Techline RE: Road stabilizers I’m doing research for a landscape architect, and I’m looking into products that reinforce the soil beneath paved roadways. So far, that has led me to a range of geotextile and geogrid systems. In this regard, geosyntheticsmagazine.com has been great. Despite how well-organized your website is, I need […]
Geocomposite drain flow capacity: ISO VS. ASTM
February 1st, 2014
From the GMA Techline RE: Geocomposite drain flow capacity: ISO VS. ASTM We are evaluating geocomposite drain products for underdrainage beneath geomembrane-lined ponds. This is an international project—we are considering non-North American products for which the hydraulic properties are based on EN ISO 12958 rather than on ASTM D4716. Would you kindly comment on how […]