CETCO‘s Tech Talk video series shares high-quality information on geosynthetics and affiliated engineering issues. Here, and in less than three minutes, Dr. Craig Benson explains how a swell index test (or, free swell) can be a good measure for how the bentonite in a geosynthetic clay liner (GCL) will react with a particular leachate. He also address the hydraulic conductivity that can be expected.

More videos are available at the company’s YouTube Channel.

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Benson provides a very accessible interpretation of these concepts, while showing complicated details on his graphs. He emphasizes the most important takeaways.

“Swells a lot? Very impervious,” he says. “Doesn’t swell very much? Very conductive.”

Utilizing the swell index provides a practical way of assessing the impact a unique site’s leachate may have on a geosynthetic clay liner. Whether it’s in waste management, mining, or some other containment sector, the swell index can be an effective tool to aid your suitability analysis and design and specification with these types of barriers.

The free swell test is outlined in ASTM D5890, Standard Test Method for Swell Index of Clay Mineral Component of Geosynthetic Clay Liners.

Dr. Craig Benson, P.E., NAE is Dean of the University of Virginia School of Engineering. Benson has been highly influential in the geosynthetics field, particularly in regards to understanding barrier system performance. For more than 20 years, he’s been involved with geosynthetic clay liners in his research.