Variability of RAP Binder Mobilisation in Hot Mix Asphalt Mixtures

Assuming the full availability of the aged binder in Reclaimed Asphalt Pavement (RAP) is one of the assumptions in the design of bituminous mixtures with RAP. However, many studies have shown that in reality only a part of the aged binder should be reflected in the mixing process. The extent of the RAP binder mobilised during mixing could have a significant effect on the performance properties of mixtures. Very little is currently known regarding the variability of this mobilisation subject to the type of RAP used. In this study, the extents of RAP binder mobilisation for RAP from three different sources were investigated and compared using the attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The results of the laboratory tests showed that there is substantial variability in mobilisation capability depending on RAP source (up to 50%). Viscosity tests on the binders indicated that the workability of the RAP binders plays a significant role in the mobilisation process. Further, chemical composition analysis through saturates, aromatics, resins and asphaltene (SARA) fractionation and microstructural characterisation using optical microscopy implied that the mobile fractions of the respective RAP binder will likely influence its ability to be active in a mixing process. Overall, it is recommended that this variability be taken into consideration, and provisions, such as improved specifications, or accommodation of special mixing conditions, such as increased temperature or mixing time depending on the rheology of RAP used, be provided.

  • Supplemental Notes:
    • This paper was sponsored by TRB committee AFK20 Standing Committee on Asphalt Binders.
  • Corporate Authors:

    Transportation Research Board

  • Authors:
    • Sreeram, Anand
    • Leng, Zhen
  • Conference:
  • Date: 2019


  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; Photos; References; Tables;
  • Pagination: 6p

Subject/Index Terms

Filing Info

  • Accession Number: 01697325
  • Record Type: Publication
  • Report/Paper Numbers: 19-04689
  • Files: TRIS, TRB, ATRI
  • Created Date: Dec 7 2018 9:24AM