ASTM Committee D35-04 have just released an updated test method.
ASTM D5890-18 – Standard Test Method for Swell Index of Clay Mineral Component of Geosynthetic Clay Liners.
The important feature of this updated test method is that the Swell Index of the clay mineral component of the Geosynthetic Clay Liner must be carried out on the source bentonite prior to the addition of polymers.
The ASTM committee recognised that the addition of polymers can significantly affect the Swell Index determined (increase) when tested under the superseded test method and which had the potential to allow the use of sub-optimal bentonites to be used in the manufacture of product.
This change ensures that the source bentonite meets minimum requirements with the Swell Index value a critical parameter in the indication of long term hydraulic performance of the specified product.
Specifiers, regulators and operators are alerted to this change and should immediately implement this document change to ensure consistency of specification of Geosynthetic Clay Liners to follow best practice procedures. As many manufacturers of Geosynthetic Clay Liners, do not publically disclose the use of polymer additives within their bentonite source, Landfill Regulators, Designers, Testing Laboratories and Auditors should verify that the bentonite tested is indeed free of chemical/polymer additives to ensure compliance with the latest test method. Bentofix® Geosynthetic Clay Liners are manufactured without the addition of polymers for bentonite modification.
Purchase of the new ASTM Standard can be made via the below link:
Please call your local office of Global Synthetics for any further details required.