Abstract
This study investigated the benefits of geogrid stabilization in unbound aggregate base layers and developed a framework to incorporate those benefits into mechanistic–empirical (ME) pavement design. The purpose was to address limitations in current design practices that treat geosynthetic stabilized and non-stabilized bases equivalently, despite evidence of enhanced stiffness and improved stress distribution from a geogrid inclusion. Field testing was conducted along US-20 in Indiana using Automated Plate Load Testing (APLT) device during the construction of three full-scale pavement test sections: control (CS), geogrid installed at the base–subgrade interface (GG1), and geogrid installed at mid-depth (GG2). Pavement instrumentation included Bender Element (BE) shear wave transducer field sensors, subgrade pressure cells and moisture and temperature sensors. APLT-derived modulus and BE sensor shear wave velocity measurements confirmed increased stiffness in geogrid-stabilized sections, with up to 23% higher local stiffness observed due to pulsed stresses. Further, long-term monitoring of BE sensor data under traffic loading through seasonal changes confirmed geogrid’s effectiveness in reducing base layer modulus reduction. A sublayer-based finite element (FE) modeling approach was developed to translate these findings as inputs into the ME pavement design framework. In accordance, the 12-in. thick base courses were discretized into six 2-in. sublayers and characterized using nonlinear, stress-dependent resilient modulus model parameters (k₁, k₂, k₃) calibrated using field data and applied through depth-specific scalar multipliers to represent the mechanically stabilized layer (MSL). The FE analysis results closely matched measured deflections, strains, and stresses, confirming the reliability of the calibrated approach. A parametric study across typical INDOT pavement sections showed that mid-depth geogrid placement (GG2) provided the greatest reduction in subgrade deviator strain and stress. These findings indicate that geogrid stabilization can be effectively represented within the ME pavement design framework using localized modulus enhancements associated with the MSL concept. Agencies can use the current research approach and the ME design framework to inform design decisions in order to quantify benefits and develop specification guidelines for geogrid-stabilized aggregate bases.
Keywords
geogrid stabilization, mechanistic-empirical pavement design, aggregate material, stress-dependent stiffness, pavement design, input calibration
Report Number
FHWA/IN/JTRP-2025/37
SPR Number
4723
Sponsoring Organization
Indiana Department of Transportation
Performing Organization
Joint Transportation Research Program
Publisher Place
West Lafayette, Indiana
Date of Version
2025
DOI
10.5703/1288284318600
Recommended Citation
Husain, S. F., Qamhia, I. I. A., Tutumluer, E., & Becker, P. J. (2025). Resilient modulus improvements to bases and subgrades from geosynthetic reinforcement (Joint Transportation Research Program Publication No. FHWA/IN/JTRP-2025/37). West Lafayette, IN: Purdue University. https://doi.org/10.5703/1288284318600
SPR-4723 Technical Summary