ASTM D8490 : 23a

1.1 This test method covers the determination of the pore size characteristics of geotextiles using an optical method and image analysis.

1.2 This method has been developed for determination of the Image Opening Size (IOS) of knitted geotextiles by image analysis. Other properties may be obtained based on the pore size distribution.

1.3 The applicability of this test method must be assessed on a product-by-product basis, as it requires light to pass through its thickness to provide a useful observation. As a general rule, the tested product must be thin. Example of products which cannot be tested using this test method is thick needle-punched nonwoven and woven with a complex three-dimensional structure.

1.4 This test method shows values in both SI units and inch-pound units. SI units is the technically correct name for the system of metric units known as the International System of Units. Inch-pound units is the technically correct name for the customary units used in the United States. The values in inch-pound units are provided for information only.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.