This standard practice provides guidance to pavement designers interested in incorporating geosynthetics for the purpose of reinforcing the aggregate base course of flexible pavement structures. Geosynthetic reinforcement is intended to provide structural support of traffic loads over the life of the pavement. For the purpose of this guide, base reinforcement is the use of a geosynthetic within, or directly beneath, the granular base course. When referring to geosynthetics, the discussion is limited to geotextiles, geogrids, or geogrid/geotextile composites. This standard was formerly designated as provisional standard PP 46.