Low-temperature fracture test for polymer-modified binders: effect of polymer structure, compatability and bitumen source in styrene-butadiene systems

Low-temperature fracture testing results for a large number of styrene-butadiene modified asphalt binders are presented. Five Strategic Highway Research Program binders (SHRP Materials Reference Library codes AAC-1, AAG-2, AAK-1, AAL, and AAN) were evaluated with 5 % by weight of different styrene-butadiene modifiers (diblock SB, linear and radial SBS), both with and without compatibilization using sulfur or carbon black. Specimens were tested in a three-point bend configuration, both with and without a notch. Fracture toughness and fracture energy in the brittle regime appear to be performance indicators that are very sensitive to the source asphalt and to the polymer's interaction with the binder (i.e. whether it is dissolved, grafted, or cross-linked). This paper discusses some of the differences between failure stress and strain and fracture toughness measurements and how these differences may relate to pavement performance. The results indicate the existence of a large range of notch sensitivities and fracture energies in different modified binders, suggesting that neither the ductile-to-brittle transition nor the direct tension failure stress (both as measured by in the SHRP direct tension test) may be totally reliable performance indicators. Fracture energy in the brittle regime may be needed for performance prediction since it combines the notched strength with a stiffness to yield a true material property independent of sample size and configuration.

Language

  • English

Media Info

  • Pagination: 91-9 (Book 1)
  • Monograph Title: Proceedings of the papers submitted for review: Eurasphalt and Eurobitume Congress

Subject/Index Terms

Filing Info

  • Accession Number: 01392439
  • Record Type: Publication
  • Source Agency: ARRB
  • Files: ATRI
  • Created Date: Aug 23 2012 7:08AM