Abstract
This is paper focuses on the evaluation of the stiffened zone in a geogrid-stabilized unbound aggregate pavement base using the newly developed bender element (BE) field sensors. A bender element pair can be used as a system of shear wave transducers to evaluate the local stiffness increase of a conventional asphalt pavement base layer in the vicinity of installed geogrids. Such an unbound aggregate base layer has been recently constructed in large-scale laboratory box tests and installed with a triangular aperture geogrid to evaluate the geogrid stiffened zone at the University of Illinois. With shear wave velocities measured at three different heights using three BE pairs, vertical stiffness profiles of the mechanically stabilized aggregate were successfully evaluated above the geogrid. In addition, dynamic cone penetration (DCP) and Light Weight Deflectometer (LWD) tests were performed on the surface of the unbound aggregates. The stiffness increases evaluated owing to the geogrid enhancement and extent of the local stiffened zone were compared to those quantified from geogrid-stabilized laboratory triaxial test specimens.