Feasibility of Gravel Road and Shoulder Recycling TR-685

Unpaved gravel road surfaces and shoulders frequently experience extensive damage due to degradation of materials under heavy traffic loading and winter/spring freeze-thaw cycles. Additionally, substantial amounts of material are typically lost to whip-off and dusting. The damage results in several problems including surface deterioration, loss of crown, surface water erosion, rutting, and potholes. Unfortunately, the most unfavorable scenarios usually occur during spring thaws and rainy seasons, when gravel roads are heavily used by planting and harvesting traffic. Current maintenance practice typically involves covering the entire damaged road surface using virgin aggregate without compaction. However, due to the continually increasing price and scarcity of virgin aggregates, this is not the most sustainable and economical solution. Most previous research on gravel road stabilization has primarily focused on using costly chemical stabilizers or geosynthetics to improve performance and durability. However, the gradation, angularity, and plasticity of surface course, subgrade, and shoulder materials are also important influence factors that evolve with time due to weathering, erosion, and abrasion by traffic loads. More cost-effective solutions may be realized by focusing on recycling and processing the existing materials to return them to the optimum gradation , angularity, and plasticity index, while minimizing the amount of virgin aggregates required. Recycling of existing materials could also be used in conjunction with chemical and mechanical stabilizers for improved performance where necessary. In the proposed project, several series of laboratory tests will be conducted to determine the optimum target gradation and fines properties of the gravel course that provide the best performance and durability. Field screening and recycling methods will be examined to restore existing aggregate materials contaminated by excessive fines to the optimum gradation to improve their performance and durability. Demonstration sections will be constructed using the most promising technologies to compare their relative performance, durability, and costs through at least one freeze/thaw cycle. Construction and maintenance of the demonstration sections will be documented, and the performance of the selected technologies will be assessed by in-situ testing. Life-cycle costs will be analyzed to identify the most effective and economical solutions.

  • Supplemental Notes:
    • Add 526


  • English


  • Status: Completed
  • Funding: $174,870
  • Contract Numbers:


    ISU proposal 129432

    Add 526

  • Sponsor Organizations:

    Iowa Highway Research Board

    Iowa Department of Transportation
    800 Lincoln Way
    Ames, IA  United States  50010

    Iowa Department of Transportation

    800 Lincoln Way
    Ames, IA  United States  50010
  • Managing Organizations:

    Iowa State University, Ames

    Center for Transportation Research and Education
    2711 South Loop Drive, Suite 4700
    Ames, IA  United States  50010-8664
  • Project Managers:

    Goetz, Vanessa

  • Performing Organizations:

    Iowa State University, Ames

    Center for Earthworks Engineering Research
    2711 South Loop Drive, Suite 4600
    Ames, IA  United States  50010

    Iowa State University, Ames

    Institute for Transportation Studies
    2711 S. Loop Drive, Suite 4700, Program for Sustainable Pavement Engineering and Research (PROSPER)
    Ames, IA  United States  50010-8864

    Iowa State University, Ames

    Department of Civil, Construction and Environmental Engineering
    Town Engineering Building
    Ames, IA  United States  50011-3232
  • Principal Investigators:

    Jahren, Charles

    White, David

    Ashlock, Jeramy

  • Start Date: 20150101
  • Expected Completion Date: 20180430
  • Actual Completion Date: 0
  • Source Data: RiP Project 38056

Subject/Index Terms

Filing Info

  • Accession Number: 01543600
  • Record Type: Research project
  • Source Agency: Iowa Department of Transportation
  • Contract Numbers: TR-685, ISU proposal 129432, Add 526
  • Files: RIP, STATEDOT
  • Created Date: Nov 19 2014 1:01AM