Resilient Modulus Improvements to Bases and Subgrades from Geosynthetic Reinforcement

Details

• Creators:
  Husain, Syed Faizan ; Qamhia, Issam I. A. ; Tutumluer, Erol ; Becker, Peter J.
• Corporate Creators:
  Purdue University. Joint Transportation Research Program
• Corporate Contributors:
  Indiana Department of Transportation ; United States. Department of Transportation. Federal Highway Administration
• Subject/TRT Terms:
  Aggregates Calibration Data Analysis Geogrids Granular Bases Input Calibration Literature Reviews Load Tests Materials Tests Mechanistic-empirical Pavement Design Pavement Design Soil Stabilization Stresses

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• Publication/ Report Number:
  FHWA/IN/JTRP-2025/37
• DOI:
  https://doi.org/10.5703/1288284318600
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States ; Indiana
• Edition:
  Final Report
• Corporate Publisher:
  Purdue University. Joint Transportation Research Program
• Abstract:
  This study investigated the benefits of geogrid stabilization in unbound granular 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 layer 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 unbound granular layer-subgrade interface (GG1), and geogrid installed at mid-depth (GG2) of unbound granular layer. Pavement instrumentation included Bender Element (BE) shear wave transducer field sensors, earth 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 to quantify benefits and develop specification guidelines for geogrid-stabilized aggregate bases.
• Format:
  PDF
• Funding:
  SPR-4723
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:389337f070351523fb0a8ed3981d7b192f2ee9f3b8907526469a67e304c66564d91f5bf6744f12c95eccc8a2990afcb6d2b993f545435cb973d523a5fcb5c94e
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/91197/dot_91197_DS1.pdf
• File Type:
  [PDF - 9.58 MB ]