Opening size recommendations for separation geotextiles used in pavements

Geotextiles are used in pavements as separators to prevent fouling of base course aggregate by subgrade soil. The ability of a geotextile to retain fines depends primarily on its opening size. A number of researchers have performed laboratory and field tests to study the retention behavior of geotextiles under dynamic conditions. However, the data generated during these studies has never been collectively analyzed. This article utilizes the published data to develop opening size recommendations for separation geotextiles used in pavements. The -85% size of soil is compared with the apparent opening size of geotextiles. The data indicates that for sand and silt size particles, a geotextile with apparent opening size (O-95) less than -85% size (d(85)) of retained soil would perform satisfactorily. However, for fine soils in suspension, the ratio of geotextile O-95 to soil d(85) should be restricted to 0.5 or less. (C) 2003 Elsevier Science Ltd. All rights reserved.