Geogrid-stabilized eco-friendly aggregates for pavement base – quantitative assessment using Bender Element sensor technology

Geogrids provide mechanical stabilization by effectively restraining aggregate movements in a granular layer which in turn improve pavement performance and extend its lifespan. This paper presents an experimental evaluation of a multi-axial extruded geogrid stabilizing two types of eco-friendly aggregates, i.e., virgin crushed limestone and recycled concrete aggregate, used in pavement unbound base/subbase applications. The study evaluated geogrid stabilized aggregate resilient modulus and permanent deformation characteristics and assessed the modulus enhancement provided by the geogrid. Repeated load triaxial tests were conducted on 152-mm (6-in.) diameter and 305-mm (12-in.) high cylindrical specimens, instrumented with embedded Bender Element (BE) shear wave transducers. Both control specimens and geogrid-stabilized specimens with geogrid placed at specimen midheight were constructed. During resilient modulus testing, shear wave velocity measurements were also taken by the transmitter-receiver BE sensor pairs embedded immediately above the specimen midheight to determine small-strain moduli. Specimen permanent deformations were then evaluated for up to 10,000 load repetitions. The geogrid-stabilized specimens had lower permanent deformations than the control specimens and provided considerable local stiffness enhancements for both the recycled and natural aggregates to demonstrate a sustainable geosynthetic application.