Quantifying Geogrid-Stabilized Aggregate Response in Dynamic Loading Environments

This paper presents a high-fidelity laboratory testing methodology to evaluate the stiffness response of geogrid-stabilized aggregate base materials under dynamic loading. While previous studies have captured cumulative effects such as densification and confinement, they have largely relied on measurements taken between loading cycles, limiting insight into transient stiffness behavior during active stress application. This study utilizes a box-scale test setup established by installing Bender Element (BE) sensors in compacted unbound aggregate layers to measure shear wave velocity as an indicator of local stiffness under both static and dynamic load applications. A new BE data acquisition protocol was developed using an oscilloscope-based setup with signal stacking and burst timing, enabling reliable waveform capture during short-duration load pulses. This protocol allowed shear wave velocities to be measured at the peak and rest phases of each loading cycle, providing direct observation of stress-dependent stiffness behavior. Geogrid-stabilized specimens with geogrids placed at mid-depth of aggregate layers were compared to control specimens for stiffness response trends. Results indicate that stabilization reduced stress-induced stiffness variations and produced higher and more uniform shear wave velocities, particularly near the geogrid. These findings represent the first direct quantification of dynamic stiffness behavior in fully confined zones of geogrid-stabilized aggregate materials.