A stiff mechanically stabilized layer (MSL) is achieved by installing a geogrid in a constructed pavement aggregate base/subbase. The inclusion of geogrid is known to improve pavement performance, yet a direct quantification and integration of geogrid benefits into pavement design has remained underutilized in many state transportation agency practices. This study attempts to address this gap by examining the integration of state-of-the-art sensor data and in-situ testing into the analysis and design of geogrid-stabilized pavement aggregate layers. Using automated plate load testing (APLT) on instrumented pavements with pressure cells and innovative Bender Element (BE) field sensors, a comprehensive paired testing effort was conducted on three pavement test sections constructed as part of the US-20 highway reconstruction project in Elkhart, Indiana. The field experiment included a control section with no geogrid and two geogrid-stabilized sections where a biaxial geogrid was installed in two different depths within the constructed unbound aggregate layers. The in-situ tests aimed to measure the composite resilient modulus and capture the deformation characteristics of the aggregate layers under repeated loading. Results demonstrated that sections stabilized with geogrids exhibited improved structural performance, evidenced by higher resilient moduli and reduced permanent deformation accumulations compared with the control section. Moreover, layer modulus enhancement ratios derived from shear wave velocity measurements with BE sensors indicated that geogrid sections exhibited increased local stiffness characteristics near geogrids. Based on the field study findings, a mechanistic approach was introduced to analyze geogrid-stabilized aggregate base/subbase and adequately incorporate their structural contributions into pavement design procedures.
Husain et al. (Mon,) studied this question.