Ultrasonic Thickness Testing of Textured Geomembranes

Measuring the core thickness of textured geomembrane is conventionally done with a dead weight micrometer equipped with tapered presser feet. In a complimentary manner, the height of the textured asperities are micrometer measured with a thin stylis. However, both methods are problematic and have led to numerous conflicts between manufacturer and specifier. This paper introduces an ultrasonic test as an alternative for both core thickness and asperity height. Findings presented in this paper show that not only the core thickness but the asperity height can potentially be obtained ultrasonically. This work is in its beginning stage and testing is currently not accurate enough to replace conventional equipment. However, it is hoped that such work will lead to the development of a standard test method that can be used by manufacturers and specifiers in the future as the precision of the method approves.