Geosynthetic clay liners (GCLs) have a tremendous record as hydraulic barriers in engineered lining and capping systems. Still, they are not necessarily well understood by the larger geotechnical design community. They require knowledge not only of geosynthetics but of sodium bentonite types, behavior, and suitability in certain applications. Dr. Craig Benson, Dean of the School of Engineering at the University of Virginia, is one of the most versed researchers in the world on GCLs and particularly in regards to bentonite and bentonite-polymer composites.

Last year, the University of Virginia partnered with international geosynthetics manufacturer Solmax to bring four, free, high-level hydraulic barriers educational webinars to the engineering community. The university also provides the PDH/CEU support for registrants. The series opened in August with the above presentation on GCL fundamentals. Webinar #2 was held in November. Both presentations are now available through the Solmax YouTube Channel.

Upcoming sessions include:

  • Principles and Procedures for Evaluating GCL Chemical Compatibility– February 2021
  • Practical Lessons Learned from GCL Case Histories– May 2021


In the opening webinar, Benson introduces the fundamentals to GCL function and performance, including a description on the process by which bentonite transforms to a nearly impermeable gel when hydrated. That transition, the role of the montmorillonite fraction in the bentonite on swelling, and the resulting hydraulic conductivity sets the stage for the webinars that follow in the series.

MORE GEO: IGS Conferences in 2021 & 2022

The video above utilizes practical examples and relevant standards (e.g., ASTM) from the field. Freeze-thaw and wet-dry cycling are discussed too.


The overall education series from Dr. Benson gives participants numerous tools to support their work in waste management, coal ash, mining, construction, environmental protection, and other critical infrastructure projects. Benson’s series is particularly notable for its strong focus on chemical compatibility and GCL use in “aggressive conditions.”

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