Synthesis of Use of Crumb Rubber in Hot Mix Asphalt

This study started with a significant literature review and analysis of trends reported in the literature regarding ground tire rubber (GTR) reaction time and attempts to dissolve it in asphalt. The results of the literature review were summarized in a white paper that is included in Appendix A of this report. In addition to the literature review, an extensive experimental plan was conducted to compare different GTR modified binders produced using recycled tire rubber by altering the percent modifier used, the reaction time allowed during the blending process, and the temperatures at which this blending was performed. This study investigates the variability in properties as the time exposed to elevated temperatures progresses, as the potential for material degradation during this period may increase. Multiple percentages of GTR were used to modify the same base binder and each of these percentages was prepared at a range of reaction times. Each binder was characterized using current Superpave procedures, although it is argued that several testing procedures may not be appropriate for GTR-modified binders. Data collected in this study generally shows that standard Superpave procedures can be used for GTR modified binders, resulting in effective binder characterization. In addition to testing binders modified with GTR, binders and mixtures produced with other types of polymer modifiers were produced and tested. Mixtures were produced using one aggregate source and gradation mixed with four binders including the neat/unmodified binder, the neat binder modified with an elastomeric polymer, a plastomeric polymer, and with GTR. All three modifications were done to modify the base binder, which is a PG 64-22, to an equivalent PG grade of PG 76-22. Repeated creep testing was performed on the mixes to determine if the elastic or plastic effects of corresponding binders was observed, and GTR mix response was compared to the response of mixes containing the polymer-modified asphalts to determine the elastic versus plastic effects of the GTR. In addition to mechanical testing, two-dimensional (2D) image analysis was performed on the mixtures to allow for quantification of the aggregate structure to determine if the decreased solubility of GTR influences the aggregate structure within the mix. This characterization was then compared to the mechanical performance to see if internal structure may serve as an indicator of a mixture’s resistance to permanent deformation.


  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; References; Tables;
  • Pagination: 45p

Subject/Index Terms

Filing Info

  • Accession Number: 01531743
  • Record Type: Publication
  • Files: TRIS, ATRI, USDOT
  • Created Date: Jul 26 2014 12:51PM