While geosynthetic clay liners (GCLs) are composite materials by design, the newer wave of multi-component GCLs are enhancing the performance of GCLs in a range of applications in a way that represents a significant jump for an already refined engineered materials area. The use of special polymeric coatings on a GCL is providing longer services lives for these materials, including in far more challenging containment scenarios.
Why the coatings? By coating one of the durable geotextile layers, manufacturers and designers are finding they can deliver greater frictional characteristics for use on steeper slopes. They are also finding even better fluid containment performance, enhanced desiccation resistance, better performance as a root barrier, and greater protection against ionic exchange and piping.
Geosynthetica’s editor Chris Kelsey sat down with Kent von Maubeuge of NAUE to discuss the state of practice with these state-of-the-art geosynthetics.
NAUE is a leading producer of geosynthetic clay liners and other geosynthetics. In the late 1980s, NAUE was honored with an IGS Award from the International Geosynthetics Society for the company’s needlepunching innovation with GCLs. That advance set the stage for massive market growth for these barrier solutions.
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Kent von Maubeuge has been extremely active in his career with helping advance the standardization of geosynthetic clay liners. He edited the 2013 ASTM publication on “Current and Future Practices for the Testing of Multi-Component Geosynthetic Clay Liners” and received the Society’s highest honor—an Award of Merit—in 2019. Between these points, he also delivered the prestigious Koerner Lecture in 2018 on geosynthetic barrier systems and international standardization.
MULTI-COMPONENT GCLS
“The multi-component part of a GCL cannot replace a traditional geomembrane,” von Maubeuge said.
This is an important distinction. Double-liner systems, such as are commonly used in landfill engineering, utilize GCLs and geomembranes. Multi-component GCLs are not to be interpreted as replacing the primary geomembrane liner in those situations.
Nor are these new materials a way to push the boundaries of what is an acceptable mass per unit area of bentonite in a GCL. It’s about enhancing performance and extending the range of applications in which geosynthetic clay liners can be used.
“It’s always a good idea to spot the weaknesses of any type of product and improve it,” he says. “That’s what we are doing with multi-component GCLs.”
The development path for multi-component GCLs extends back to the early 2000s. Enough advances had been charted by 2011 (with no real support having appeared yet in the standards community) that a special symposium was held on these materials in June 2012 during ASTM Committee D35 on Geosynthetics’ meeting. The resulting publication, released in 2013, looked at testing of multi-component GCLs. The 15 papers in the book delivered true international perspective and broad contributions from manufacturing, design, and installation.
“These material advancements have continued to extend the suitability and survivability of geosynthetic clay liners in a variety of containment designs,” the editors wrote at the time. “But, they have also complicated standardization in ways that could inhibit market growth and acceptance if the changes too greatly outpace the standards community’s ability to provide guidance and leadership within the larger geotechnical engineering field.”
Today, ASTM standards such as D5993 (Measuring Mass per Unit Area of Geosynthetic Clay Liners) from Subcommittee D35.04 on Geosynthetic Clay Liners note the applicability of the standard to multi-component GCLs.
THE TAKEAWAY
These materials demonstrate enormous barrier effectiveness and the demand for them is rising, especially in environmental protection.
