Optimization of the Design of Flexible Pavements with Unbound Bases Reinforced with Geogrids Using Apt

Base reinforcement results from the addition of a geogrid at the bottom of, or within an unbound base course to increase the structural or load-carrying capacity of a pavement system. TxDOT has significant experience in the use of geogrids to mitigate detrimental effects caused by expansive clay subgrades on flexible pavements. In the national arena, the main motivation to use geogrids in the design of unbound bases has been to resist traffic loads, rather than environmental loads. In these cases, the objectives have been to increase the design life of a pavement (for a given base thickness) or to decrease the required thickness of its base course (for a given design life). Many field-monitored projects, including accelerated pavement testing (APT) projects, have involved geogrid-reinforced pavements (GRPs). Yet, while previously collected field data are certainly valuable, the overall focus has been on quantifying how much improvement the geogrids can add to a pavement base course rather than on understanding why GRPs behave as they do. This focus may have precluded incorporating this promising technology into a rational methodology for pavement design. This project's objective is to determine the actual contribution of geogrids to the performance of flexible pavements and incorporate this understanding into tools that allow a rational design of GRPs. Achieving the objective requires overcoming key hurdles: 1) understanding the behavior of GRPs; 2) capitalizing on this understanding to identify the material properties that govern GRP performance; and 3) incorporating this understanding and properties into a robust design framework. Accordingly, a work plan has been conceived that includes both the long-term pavement performance (LTPP) of field sections as well as a comprehensive APT program on geogrid-reinforced pavement sections. The significant volume of field and experimental data collected in this project will yield key project deliverables: comprehensive reports, geogrid selection criteria, documentation of geogrid testing protocols with threshold values for accepting properties, and modification of the Flexible Pavement Design System 19 (FPS-19) program to account for the presence of geogrid reinforcement in unbound bases. In addition, a set of Special Specifications will update TxDOT's DMS-6240, easing the selection of geogrids for the reinforcement of unbound bases. Finally, to facilitate implementation, a pilot short course will be offered to TxDOT personnel to discuss the best practices for using geogrids in pavement design as well as the associated costs and benefits.


  • English


  • Status: Completed
  • Funding: $468,937.00
  • Contract Numbers:


  • Sponsor Organizations:

    Texas Department of Transportation

    125 E. 11th Street
    Austin, TX  United States  78701-2483
  • Project Managers:

    Glancy, Chris

  • Performing Organizations:

    Center for Transportation Research

    University of Texas, Austin
    Austin, TX  United States  78759
  • Principal Investigators:

    Zornberg, Jorge

  • Start Date: 20150901
  • Expected Completion Date: 20180831
  • Actual Completion Date: 20180831
  • Source Data: RiP Project 39602

Subject/Index Terms

Filing Info

  • Accession Number: 01566802
  • Record Type: Research project
  • Source Agency: Texas Department of Transportation
  • Contract Numbers: 0-6834
  • Files: RIP, STATEDOT
  • Created Date: Jun 23 2015 1:01AM