Role of Asphalt Binder Fracture Properties in Thermal Cracking Performance of Mixtures and Pavements

Significant progress in controlling low temperature cracking has been achieved by introducing the Bending Beam Rheometer (BBR) and placing appropriate limits on stiffness and relaxation rate (i.e., S and m-value). However, with the increase in types of modifiers and extender oils used to achieve special low temperature grades (e.g., PG xx-28 and PG xx-34), concerns about the effects of these additives on the fracture properties of binders have been raised. The need for a testing system that is simple and effective in measuring these properties is clearly realized. A Single-Edge Notched Bending Test based on a modification of the standard BBR device (BBR-SENB), was developed and used to measure fracture properties of asphalt binders. Comparison of BBR-SENB results with fracture properties of asphalt mixtures and field performance indicates the need to compliment current practice of using stiffness and relaxation properties measured in the BBR with binder fracture properties to evaluate thermal cracking of pavements. It is observed that binders of the same low temperature PG grade can have significantly different fracture energy (Gf) and deflection at fracture (uf), measured at the grade temperature. For example, binders graded as PG (xx-22) showed Gf values ranging between 1 and 30 J/m2 measured at -12 deg C. (A)

Language

  • English

Media Info

  • Pagination: p. 239-55
  • Monograph Title: Proceedings of the Fifty-Seventh Annual Conference of the Canadian Technical Asphalt Association: Vancouver, British Columbia November 2012

Subject/Index Terms

Filing Info

  • Accession Number: 01494236
  • Record Type: Publication
  • Source Agency: Transportation Association of Canada (TAC)
  • Files: ITRD, TAC
  • Created Date: Sep 24 2013 12:57PM