Geotextile Filter Design Using Pore Size Distribution

Current geotextile filter design methodologies rely on geotextile apparent opening size (AOS) measurements obtained from ASTM D 4751. Even though a typical geotextile sample has a range of opening sizes, the current standard of practice is to use ASTM D4751 to obtain a single AOS value that is used for filter design of soils with a wide range of particle sizes. The AOS is a property of the geotextile that indicates the approximate largest particle that would effectively pass through the geotextile. It is also commonly referred to as the O₉₅ of the geotextile. In recent years, geotextile pore size distribution (PSD) is being obtained in accordance with ASTM D6767. PSD results yield a spectrum of opening sizes that represent a geotextile’s ability to retain soil particles, as opposed to a single “largest opening size” value that is obtained from AOS testing per ASTM D4751. A new geotextile filter design method using multiple retention criteria has been created through a synthesis of the existing body of knowledge combined with laboratory testing to validate the new design methodology.