Towards a further understanding of the role of the creep time in the MSCR test and proposal of a refined traffic level criterion

Currently, the technical literature suggests intervals of vehicle speeds based on the maximum nonrecoverable compliance (Jnr) for each traffic level. Although these speeds are somewhat related to the loading times in the real pavement, the actual resistance of the binder at longer creep times in the multiple stress creep and recovery (MSCR) test is not considered. Such a problem could be solved if the material complied with one additional requirement to deal with heavier traffic levels, i. e., showing Jnr no greater than a predefined value in a more severe testing condition. In order to examine this hypothesis, four modified binders (AC+PPA, AC+Elvaloy+PPA, AC+SBS, and AC+EVA) with the same high-temperature performance grade were evaluated in the MSCR tests at 64 and 70°C using the standardized creep times (1/9 s) and three longer ones (2/9, 4/9 and 8/9 s). As a result of this study, an early draft of the revised traffic criteria was produced. Doubling the creep time led to less rut resistant formulations (R decreased and Jnr increased) and, in many cases, the traffic levels were decreased by one grade. The AC+Elvaloy+PPA yielded the most promising findings in the MSCR tests, including the stress sensitivity criteria. The AC+EVA typically showed higher rutting resistances than the AC+SBS, especially from the point of view of Jnr. The power models fitted the data quite well, but in-depth analyses about binder nonlinearity are not possible due to the poor degrees of correlation with R and Jnr and values of n close to unity.

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

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Faxina, Adalberto Leandro
  • Inocente Domingos, Matheus David
• 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; References; Tables;
• Pagination: 14p
• Monograph Title: TRB 96th Annual Meeting Compendium of Papers

Subject/Index Terms

• TRT Terms: Bituminous binders; Rutting; Traffic loads
• Identifier Terms: Multiple Stress Creep Recovery
• Uncontrolled Terms: Creep compliance; Modified binders; Multistress creep and recovery test
• Subject Areas: Highways; Materials; Pavements;

Filing Info

• Accession Number: 01629828
• Record Type: Publication
• Report/Paper Numbers: 17-06401
• Files: TRIS, TRB, ATRI
• Created Date: Mar 26 2017 5:39PM