Geosynthetic stabilization of road pavements, railroads, and airfields

Geosynthetics provide sustainable alternatives for enhanced performance, durability and cost-effectiveness of road pavements, railways, and airfields. Even when the same geosynthetic products are used for constructing these different transportation facilities, an optimal approach is needed to match the properties of soils or unbound aggregate geomaterials and the geosynthetic products to establish an effective mechanical stabilization. This Proctor lecture keynote paper presents the state-of-the-practice on the transportation applications of geosynthetics, design methods, and the recent research findings on geosynthetics used in road and airfield pavements and ballasted railway tracks. The paper introduces first the transportation applications of commonly used geosynthetic products, i.e., geogrids, geotextiles, and geocells, with special emphases to subgrade restraint and unbound aggregate stabilization applications and discusses in detail the related unpaved and paved design procedures. Next, the focus is directed towards establishing a better understanding of geosynthetic mechanisms governing stabilization applications. To summarize, this keynote paper reports on two decades of developments and research findings at the University of Illinois and elsewhere on the topic of geosynthetic stabilization using the latest technologies to quantify the stiffness enhancement in the vicinity of a geosynthetic material via the bearing capacity improvement and lateral restraint mechanisms. Recent research at the University of Illinois focused on the successful use of bender element shear wave transducer technology is discussed in detail with several examples given related to the laboratory and field efforts of unbound aggregate base and railroad ballast geosynthetic stabilization including full-scale instrumentation of stabilization geosynthetics used in actual road and airfield pavements constructed in the United States.