Utilization of Ground Tire Rubber for Energy Efficient Pavements

Iowa State University (ISU) has assembled a team of experts in Civil, Chemical and Industrial and Manufacturing Systems Engineering to address the challenges of integrating scrap and end-of-life rubbers to supplant the use of up to 140,000 tons/year of virgin polymer used in asphalt pavements. The team proposes the use off-specification polybutadiene to modify ground tire rubber (GTR) particles, from recycled tires, and use them as an asphalt modifier to replace widely used SBS elastomers. GTR is currently being used as a modifier, which offers comparable improvements with respect to SBS polymers such as rutting resistance and elastic recovery, with advantages such as improved traction and reduced noise. However, because of the difference in density with asphalt it suffers from inadequate storage stability, rendering it an unpreferred material in asphalt modification.1,2 ISU has developed a technology that density matches GTR with asphalt with simple compounding techniques, producing a GTR product that meets storage stability specifications and would be accepted by the market.3,4 If 100% of virgin polymer were replaced with recycled GTR, up to 140,000 tons/year could be reclaimed nationwide. Moreover, asphalt pavements are 100% recyclable, including as a major component of new roadways, which means that GTR used in pavements will continue to be reused. The objectives of this project are to determine if utilizing PEX is both performance and cost advantaged alternative to the use of more traditional SBCs. Within the context of this proposal, the specific objectives are: 1. Synthesize GTR blends that will remain homogeneously suspended in asphalt binder 2. Determine the optimum blending variables (dosage, time, temperature) 3. Improve rheological properties of the top GTR blends over a range of asphalt binder grades 4. Compare results of GTR-modified asphalt using GTR/isoprene polymers from multiple sources to the same asphalt binders modified with SBCs in both asphalt binder and asphalt mixture performance tests 5. Conduct demonstration asphalt field paving trials and post-construction assessment.


    • English


    • Status: Active
    • Funding: $240,402.00
    • Contract Numbers:


      Addendum 740

      ISU 148282

    • Sponsor Organizations:

      Iowa Department of Transportation

      800 Lincoln Way
      Ames, IA  United States  50010

      Iowa Highway Research Board

      Iowa Department of Transportation
      800 Lincoln Way
      Ames, IA  United States  50010
    • Managing Organizations:

      Iowa Department of Transportation

      800 Lincoln Way
      Ames, IA  United States  50010
    • Project Managers:

      Goetz, Vanessa

      Hensley, Timothy

    • Performing Organizations:

      Iowa State University, Ames

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

      Williams, Chris

      Cochran, Eric

    • Start Date: 20200801
    • Expected Completion Date: 20230228
    • Actual Completion Date: 0

    Subject/Index Terms

    Filing Info

    • Accession Number: 01744696
    • Record Type: Research project
    • Source Agency: Iowa Department of Transportation
    • Contract Numbers: TR-787, Addendum 740, ISU 148282
    • Files: RIP, STATEDOT
    • Created Date: Jul 7 2020 9:29AM