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The 2023 Koerner Lecture Q&A session
April 1st, 2024
George Koerner: Geomembranes used as landfill liners may experience differential settlement or local strain due to protrusions or anomalies in the subgrade. Therefore, it is important to define a maximum allowable strain that any given geomembrane can tolerate without compromising its integrity. Do you have an opinion on what this strain limit should be for […]
New GSI test method for resistance of conductive geosynthetics
June 1st, 2022
The Geosynthetic Institute (GSI) has a new test method for resistance measured across positions on conductive geosynthetics. Conductive geosynthetics contain an electrically charged backing (usually a thin layer of polyolefin with letdowns containing 20%–30% carbon black) that allows leaks to be detected in lined systems without the need for a conductive subgrade beneath the liner […]
Adding graphene to geosynthetics
June 1st, 2022
Q: I have some commercial application questions in the field of geosynthetics. We manufacture graphene powders in the most sustainable way, and it allows us to supply graphene to manufacturers much more economically. As you may have heard, graphene has wonderful material properties atomically to offer, and I am looking for opportunities to leverage its […]
Landfill trenches with geocomposites
June 1st, 2022
Q: I am wondering if you know of or can point me in the right direction in regard to determining viability of leachate disposal via spraying back onto the active face of a landfill. I have a landfill that has a few issues, and while, from a practical sense, we have had some success with […]
Scratch impact on HDPE liners
April 1st, 2022
Q: I have a project where multiple and extensive scratches were created on the high-density polyethylene (HDPE) liner for a reservoir due to poor construction practices. (See the following Figures 2–4.) FIGURE 2 Construction equipment that caused scratches at crest of slope FIGURE 3 Overview of scratches in 60-mil (1.5-mm) high-density polyethylene (HDPE) conductive liner […]
Methane gas geomembrane permeability
April 1st, 2022
Q: What is the least permeable geomembrane to methane gas? Regarding the permeability of geomembranes to methane gas, could you send me some technical guidelines? A: High-density polyethylene (HDPE) geomembranes are denser (more crystalline) than linear low-density polyethylene (LLDPE) geomembranes and less permeable. The water vapor, solvent and methane transmission (diffusion) of an HDPE barrier […]
High pH effects geogrids?
April 1st, 2022
Q: Can you tell me whether the high pH of curing portland cement (typically ~12.4) might have any impact on the long-term performance of geogrids? A: It depends on the geogrid and its formulation. There are three categories of geogrid: (1) punched and drawn (polyethylene [PE] uniaxial, polypropylene [PP] biaxial and triaxial), (2) strap (polyvinyl […]
LCC curing effect on geogrids
April 1st, 2022
Q: Can you tell me whether modest warming of geogrids (e.g., due to heat generated by the curing of lightweight cellular concrete [LCC]) might impact the long-term strength or long-term modulus of geogrids? A: You need to know the maximum temperature due to the heat from hydration of the LCC. Most pozzolanic reaction temperatures (like […]
Calendared nonwoven geotextiles
April 1st, 2022
Q: What is the difference between normal nonwoven and calendared nonwoven (both needlepunched) geotextiles? Where can we use calendared nonwoven geotextiles? A: Calendared nonwoven geotextiles are passed between a set of heated rollers that applies normal pressure as a tertiary process of the production. This process increases the modulus, strength, tear resistance, puncture resistance and […]
GCL-GM geocomposite: Which end is up?
April 1st, 2022
Q: In a geosynthetic clay liner-geomembrane (GCL-GM) geocomposite, does it make any difference which side of the geocomposite is up: GM or clay? A: This is a very detailed question that is application specific. The following design details all need to be considered: Is the GCL-GM geocomposite used for a liner or a cover, is […]