The IFAI Bookstore has geosynthetics books, videos, CDss and conference proceedings.
NOTE: Members of the International Geosynthetics Society (IGS) have access to conference proceedings from around the world and going back more than 35 years via www.geosyntheticssociety.org. Before you spend $99 on a set of old proceedings, update your IGS membership (USD $45/yr) and check the IGS members-only archives.