Erol Tutumluer, Ph.D., Dist. M.ASCE, University of Illinois Urbana-Champaign

Geosynthetic stabilization is often associated with a paved road when an aggregate base/subbase is constructed over a subgrade having CBR ranging from 3 to 8 (FHWA, 2008). The main benefits of unbound aggregate layer stabilization include (1) decreasing time-dependent rutting by providing an increased modulus of unbound aggregates at the time of construction and added confinement from compaction-induced geosynthetic tension and (2) minimizing degradation of the modulus of unbound aggregates over time by proper control of lateral displacements in unbound aggregates and maintaining initial confinement of unbound aggregates. The identified mechanism is the development of lateral restraint through tension and shear transfer to minimize the lateral displacement of unbound aggregates. Both friction and interlocking between aggregates and geosynthetics contribute to the base stabilization. Modern design procedures are needed for establishing more common use of geosynthetics for base stabilization within the framework of a mechanistic-empirical pavement design approach. This workshop is intended to present, review an discuss the latest developments in the quantification of aggregate layer stiffness characteristics of the geosynthetic-aggregate geocomposite, aka, the mechanically stabilized layer. Through presentations and discussion, a path to development of modern design procedures will be presented.