Full-scale field study and finite element modeling of a flexible pavement containing geosynthetics

Problematic construction soils are located in the delta of eastern Arkansas and similar areas along the Mississippi river basin. These fine grained soils consist mostly of clay and do not possess high strength characteristics in the presence of water. They are a poor substitute for high quality subgrade materials in a flexible pavement application because they tend to migrate (pump) into adjacent layers and reduce the engineering properties of all layers. As a result, flexible pavements constructed on poor subgrade soils have a higher tendency to develop ruts, fatigue cracks, and other undesirable characteristics.; The use of geosynthetic materials has shown potential for improvement of pavement performance under such conditions, but the extent of improvement and mechanism(s) responsible are not completely understood. Thirteen test sections in a full scale flexible pavement were constructed and instrumented using ten different types of sensors. Two different base course thicknesses and different geosynthetic materials were incorporated into the field study. A unique data acquisition program was written specifically for this application.; Traffic, falling weight deflectometer, environmental, and pavement condition data were collected seasonally. Over 2,000 passes were made with pre-weighed dump trucks loaded to the approximate legal limit, over 500 drops were made with the falling weight deflectometer, and this data was complimented with applicable environmental (temperature, rainfall, moisture content) and pavement condition (rutting and fatigue cracking) assessments.; The primary techniques used in performance assessment were Asphalt Institute Transfer Functions. The calculated performances were compared to the pavement condition assessments and, in general, were agreeable. As a compliment to the field study, a non-linear finite element model was created that applies a transient load to the pavement. The model over predicted measured stresses and strains induced by vehicular loads by moderate amounts. The performance of the model under the field conditions encountered was satisfactory.; No definite conclusions were made regarding the effect of the geosynthetics on the flexible pavement. Weather conditions were unusually dry for the area where the pavement was constructed. All major components of the study, though, performed satisfactorily and possible continued monitoring could shed additional light on the behavior(s) under investigation.