Modeling geogrid-stabilized aggregate base courses considering local stiffness enhancement

Lateral restraint is the primary stabilization mechanism associated with the interlocking of aggregate particles in the geogrid apertures. This paper presents findings from a laboratory study which quantifies the local stiffness enhancement of aggregates through micromechanical interlocking provided by two different types of geogrids. These findings are applied to model the resilient response characteristics of geogrid-stabilized base course composite systems. Using three pairs of bender elements as shear wave transducers, horizontal stiffness profiles were determined above mid-heights of aggregate specimens. For two types of geogrids with square- and triangular-shaped apertures, the shear modulus profiles decreased moving away from the geogrid location. Based on a relationship for aggregates, resilient modulus was estimated from the shear modulus. Considering the variations in resilient moduli with distance from the geogrid location, the local stiffness enhancements provided by the two geogrid types were assigned to modulus profiles of a geogrid-stabilized aggregate base course in flexible pavement mechanistic analysis and modeling. The modeling results demonstrate the effect of geogrid base stabilization on the computed pavement resilient responses for both geogrid types. The sublayering approach which properly considers modeling of the geogrid influence zone could be effectively used in mechanistic analysis of a geogrid-stabilized pavement system.