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Part 2: Field evaluation of the performance of unpaved roads incorporating geosynthetics—Planning

April 1, 2016

Introduction Scope and terminology The mechanisms that govern unpaved road performance are complex. Therefore, it is legitimate to try to get quantitative data from laboratory and field tests, but test interpretation can be correct only if there is a good understanding of the mechanisms (which was the purpose of the Part 1 article), rigorous planning …

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Part 1 Durability of geosynthetics: The basics

August 1, 2015

By John H. Greenwood Author’s note This article is based on a training presentation delivered on Sept. 24, 2014, at the 10th International Conference on Geosynthetics in Berlin, Germany. That talk was itself based on courses given at ERA Technology, Leatherhead, U.K., with Alan Friday, and later at SKZ in Würzburg, Germany, with the participation …

ASTM announces new geogrid standard

July 21, 2015

A new geogrid test method from the standards organization, ASTM International, has been issued, according to a July 20 ASTM press release. The release said that the test described in the standard—D7864/D7864M, Test Method for Determining the Aperture Stability Modulus of Geogrids—will help ensure that geogrids meet product specific calibrated and validated levels of aperture …

Gaining a better understanding of the porometer test (ASTM D6767)

June 1, 2015

By Bruce Lacina and Melissa Medlin 1. Introduction The ASTM international standard test method for pore size characteristics of geotextiles by capillary flow test provides a wealth of information about the physical makeup of the structure and pore spaces in a geotextile sample. This test is often referred to as the pore size distribution (PSD) …

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Recognizing the benefits of GRS bridge-building technology

August 1, 2012

Take the leap of faith By Jessica Bies Introduction More than seven years after the Federal Highway Administration (FHWA) and local officials in Defiance County, Ohio, built their first geosynthetic-reinforced soil (GRS) integrated bridge, county engineers throughout the U.S. are starting to recognize the benefits of using GRS bridge technology. Still promoting widespread application of …

The need for erosion control material specifications

February 1, 2012

By Bob & George Koerner The authors feel that a reasonable case can be made that generic specifications have significantly aided both geotextile materials (e.g., via AASHTO specs) and geomembrane materials (e.g., via GRI specs). Such specifications address most common situations and also provide a platform from which unusual or atypical site-specific conditions can be …

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HDPE & LLDPE rates

June 1, 2011

From the GMA Techline RE: HDPE & LLDPE rates I have always been under the impression that in using field tensiometers on jobsites that the rates for HDPE and LLDPE are different —HDPE at 2in./min. and LLDPE at 20in./min. However, I don’t have any documentation to back this up. Can you provide me with any …

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GG3-87

October 1, 2010

From the GMA Techline RE: GG3-87 I was wondering if guideline GG3-87 is still in use. If it is, could I get a copy? Thank you. (Jason | Kentucky) Reply: Good question and, as with many other GRI Standards, we have given the GRI method to ASTM, which now has a replacement. The replacement for …

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GRI GM13

From the GMA Techline RE: GM13 We request you to kindly send us the GRI-approved grades for manufacturing HDPE geomembrane as per GM13. (Dilip | India) Reply: The GRI GM13 specification is a template of required properties for a manufacturer to meet or exceed. If your geomembrane does indeed meet the requirements, you can say …

ASTM standards for material properties for pavement components

July 1, 2010

Two new ASTM International standards will aid in the recent national movement to develop a mechanistic-empirical design guide for pavements. Both new standards, developed by ASTM International D35 on Geosynthetics, will cover quantification of fundamental material properties for pavement components. The standards, ASTM D7499, Test Method for Measuring Geosynthetic-Soil Resilient Interface Shear Stiffness, and ASTM …