Evaluation of Test Method Alternatives for Thermal Cracking Characterization of Asphalt Binders

Current Department of Transportation (DOT) state specifications for asphalt binders can be classified into two main categories: PG and PG plus. There is a general consensus that the PG grading provides valuable information regarding pre-failure engineering properties of asphalt binders. The Bending Beam Rheometer (BBR) is used in the PG system (AASHTO M320) to characterize low temperature cracking resistance based on Stiffness (S) and logarithmic creep rate (m-value) which are both measured at low levels of stress and strain. Thus, there is a concern that resistance to cracking is not fully captured by the BBR testing device. Since the Direct Tension Test developed in the PG system is seldom used, a new test called Single Edge Notched Bending (SENB) test was recently developed to measure low temperature fracture properties. Preliminary testing results with the SENB show that there is a strong relationship between SENB fracture properties and thermal cracking resistance of asphalt mixtures. However, as the SENB device is not available commercially, there is an immediate need to explore simpler alternatives for evaluating binders’ cracking at low temperatures. In this study, a total of thirteen modified binders and the corresponding plant produced mixtures were collected from five different states. Each binder was tested to measure various material properties including fracture energy and ductility. The objective of this study is to investigate the relationship between binder PG+ tests, such as SENB fracture test, and mixture low temperature cracking properties to determine the simplest binder test that can reasonably correlate with mixture performance testing. Results of the study concluded that SENB Failure Energy of binders correlates very well to mixture strength and failure energy. Due to the practical constraints of implementing a fracture test into DOT specifications, a derived model that includes a combination of DSR based and BBR based results is proposed as an alternative method for estimating fracture properties of asphalt binders at low temperatures.

• Supplemental Notes:
  • This paper was sponsored by TRB committee AFK20 Standing Committee on Asphalt Binders. Alternate title: Evaluation of Alternatives for Thermal Cracking Characterization of Asphalt Binders.
• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Lyngdal, Erik
  • Varma, Remya
  • Teymourpour, Pouya
  • Bahia, Hussain U
• Conference:
  • Transportation Research Board 96th Annual Meeting
  • Location: Washington DC, United States
  • Date: 2017-1-8 to 2017-1-12
• Date: 2017

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; Photos; References;
• Pagination: 17p
• Monograph Title: TRB 96th Annual Meeting Compendium of Papers

Subject/Index Terms

• TRT Terms: Bituminous binders; Cracking; Fracture properties; Low temperature; Test procedures; Thermal degradation
• Uncontrolled Terms: Single edge notched bending test
• Subject Areas: Highways; Materials; Pavements;

Filing Info

• Accession Number: 01625626
• Record Type: Publication
• Report/Paper Numbers: 17-04647
• Files: TRIS, TRB, ATRI
• Created Date: Feb 8 2017 4:23PM