A new specification for geotextile grout filled mattresses

April 1, 2021

By George R. Koerner Geotextile grout filled mattresses (GGFM), also referred to (in ASTM D18.25/D35.05) as fabric-formed concrete (FFC) or fabric-formed concrete revetments (FFCR), are erosion-resistant concrete linings made from durable, permeable fabric forms that are filled with high-strength grout. GGFMs are generally sloping structures placed on shorelines to absorb the energy of incoming water. …

Extreme direct shear testing

February 1, 2021

By George R. Koerner The Geosynthetic Institute (GSI) is doing direct shear testing under extreme environmental conditions (i.e., specifically extreme temperatures). At the prompting of two member companies, we have initiated an effort in this regard. This work looks at response curves over a wide range of normal pressures, 0–43.5 psi (0–300 kPa). The work …

Testing wind-resistant geosynthetics

October 1, 2020

By George R. Koerner As you can see by Figure 1, we are experiencing a new age of geosynthetics. Over the past 15 years, we have seen a propensity of polymeric materials left exposed to rather than covered from the environment. This is in large part due to the strides geosynthetic manufacturers and polymer formulators …

Benefit/cost analysis as it relates to service life of geosynthetics

August 1, 2020

On the surface, performing a benefit/cost (B/C) analysis is a straightforward process. However, ensuring that such an analysis is accurate and thorough is a much more nuanced task. In 2008, Bob Koerner laid out the procedure for geomembranes in Geosynthetic Research Institute (GRI) White Paper #12 “GS Selection Based on B/C Ratio.” This article expands …

GSI to host webinar on stabilization with nailed or anchored geosynthetics the Wednesday

June 22, 2020

The Geosynthetic Institute (GSI) will sponsor a webinar, “In-Situ Stabilization of Soil Slopes Using Nailed or Anchored Geosynthetics,” on June 24, from 11:30 a.m. to 1 p.m. EDT. Geosynthetic Materials Association (GMA) member companies and their employees receive discounted rates on all GSI webinar and short course registrations. The sliding of soil slopes in the …

Test method for determining leakage through imperfections in GMs of a composite liner system

June 1, 2020

George R. Koerner This article describes a large-scale test method intended to determine the leakage through imperfections in a geomembrane (GM) under a given head. It can be used as a performance test to simulate field conditions where the GM is physically breached. The test method places a GM test specimen of 2 feet (0.6 …

GSI issues request-for-proposals for graduate student fellowships

May 18, 2020

The Geosynthetic Institute (GSI) announces a worldwide request-for-proposals (RFP) focusing on innovative geosynthetics research and development projects. There will be several awards given, each for $5,000. Emphasis will be placed on relevant topics of interest and/or concern to the geosynthetics community. The proposals must be submitted in the following four-page format: Page 1 – Letter …

How does your geosynthetic react to changes in temperature?

April 1, 2020

An essential aspect of geosynthetics is that they function well over a large range of temperatures in either buried or exposed environments. There has been much work in this area; see Giroud and Morel (1992), Koerner and Koerner (1995 and 2006), Lord, Soong and Koerner (1995), and Tsuboi, Imaizumi and Miyaji (1998). Most of the …

The GMA Techline is 15 years old

February 1, 2020

By Robert M. Koerner The GMA Techline was initiated on Sept. 1, 2004, as a free worldwide answer center for questions involving any, or all, aspects of geosynthetics. There were no constraints put on the questioners, or on the answers that were provided by the Geosynthetic Institute (GSI). To date, 3,500 Q and As have …

A forty-year anniversary for the first hardbound book on geosynthetics

October 1, 2019

By Robert M. Koerner In the late 1970s, I regularly invited speakers to make presentations to my geotechnical engineering classes at Drexel University. Two of them were very memorable: Bill Ragen of Mirafi and Bill Witherow of Carlisle. Their respective topics were “filter fabrics” and “pond liners,” and in truth I didn’t associate them with …