Determining the Effective PG Grade of Binder in RAP Mixes

This report presents the results of a research study to develop a method to determine or estimate the binder grade in mixtures designed with recycled asphalt pavement (RAP) from the properties of the mixture itself. A 12.5 mm Superpave mixture was used to evaluate mixtures containing 0% RAP, 10% RAP, 25% RAP, and 40% RAP with a virgin PG 64-28 binder. Virgin mixtures with PG 58-28, PG 70-22, and PG 76-22 binders were also evaluated. Testing included dynamic modulus, creep compliance, and strength tests in the indirect tensile mode. Partial |G*| master curves were measured on the extracted binder from each mixture and the recovered binder was also PG graded. Several methods of estimating the effective PG grade of the binder were evaluated. Empirically based methods of interpolating values of measured mixture properties are straightforward, but require an extensive amount of testing in the laboratory. The relationship between material properties and PG grade must be established for each type of mixture (gradation, asphalt content). The most promising methods for determining the effective PG grade of the mixture use the Hirsch model to back calculate binder |G*| from the measured mixture dynamic modulus. This report summarizes the research effort and provides a recommended procedure for estimating the effective PG grade of binders in RAP mixtures.

Language

  • English

Media Info

  • Media Type: Print
  • Edition: Final Report
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 98p

Subject/Index Terms

Filing Info

  • Accession Number: 01153219
  • Record Type: Publication
  • Report/Paper Numbers: NETCR78, Project No. 04-4
  • Files: TRIS, USDOT
  • Created Date: Mar 24 2010 3:07PM