GUIDELINES FOR USE OF MODIFIERS IN SUPERPAVE MIXTURES: EXECUTIVE SUMMARY AND VOLUME 1 OF 3 VOLUMES: EVALUATION OF SBS MODIFIER

A laboratory investigation was conducted to evaluate the effects of Styrene Butadiene Styrene (SBS) polymer modification on the cracking resistance and healing characteristics of Superpave mixtures. Asphalt mixtures with low and high design asphalt contents using unmodified and SBS modified asphalt cements were produced in the laboratory. Tests performed with the Superpave Indirect Tensile Test (IDT) included resilient modulus tests, creep tests, repeated load fracture tests, healing tests, strength tests at two loading rates, as well as longer-term creep tests to failure. The test results showed that the benefit of SBS modifiers to mixture cracking resistance appeared to be derived primarily from a reduced rate of micro-damage accumulation. The reduced rate of damage accumulation was reflected in a lower m-value without a reduction in fracture limit. However, SBS modifier does not appear to influence healing or aging of asphalt mixture. Therefore, it was shown that the benefits of the SBS modifier were clearly identified by using the Hot Mix Asphalt (HMA) fracture model, which accounts for the combined effects of m-value and fracture energy limit on cracking resistance. It was also determined that the residual dissipated energy as determined from Superpave IDT strength tests appears to be uniquely associated with the presence and benefit of SBS modification, and may provide a quick way to make relative comparisons of cracking performance. Longer-term creep tests showed that time to crack initiation appeared to provide another parameter uniquely related to the effects of SBS modification. Cost analyses indicate that the construction cost of asphalt concrete (AC) layer would be reduced by using SBS modifier. Consequently, the use of SBS modified mixtures was clearly justified. In conclusion, the key to characterizing the effects of SBS modifier on the cracking resistance of asphalt mixture is in the evaluation of the combined effects of creep and failure limits.

• Corporate Authors:

  University of Florida, Gainesville

  Department of Civil and Coastal Engineering
  Gainesville, FL  United States  32611-6580

  Florida Department of Transportation

  Haydon Burns Building, 605 Suwanee Street
  Tallahassee, FL  United States  32301

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Roque, R
  • Birgisson, B
  • Tia, M
  • Kim, Beomjun
  • CUI, Z
• Publication Date: 2004-1

Language

• English

Media Info

• Features: Appendices; Figures; Photos; References; Tables;
• Pagination: 146 p.

Subject/Index Terms

• TRT Terms: Aging (Materials); Asphalt content; Asphalt mixtures; Costs; Cracking; Creep tests; Fracture tests; Laboratory tests; Modulus of resilience; Polymer asphalt; Repeated loads; Styrene butadiene styrene; Superpave
• Uncontrolled Terms: Indirect tensile test
• Subject Areas: Finance; Highways; Materials; I31: Bituminous Binders and Materials;

Filing Info

• Accession Number: 00974214
• Record Type: Publication
• Report/Paper Numbers: Final Report,, UF Proj 4910-4504-718-12,, State Job 99052793
• Contract Numbers: BC-354, RPWO #1
• Files: TRIS, USDOT, STATEDOT
• Created Date: May 17 2004 12:00AM