METHODOLOGY FOR DETERMINING COMPACTION TEMPERATURES FOR MODIFIED ASPHALT BINDERS

The equiviscous principle, which is based on the viscosities of an asphalt binder, determines the compaction temperature to be used during asphalt mixture design. When this principle is used, theoretically, all asphalt binders should provide the same optimum asphalt binder content at a 4% design air-void level when all other variables, such as compaction effort and aggregate gradation, are held constant. The compaction temperature determined by this principle is also used by asphalt paving contractors as an indicator of how workable a mixture should be during construction. The equiviscous principle was developed using unmodified asphalt binders. For some polymer-modified asphalt binders, the equiviscous principle gives a compaction temperature that is significantly higher than what is needed. Excessively high temperatures may damage the asphalt binder, generate fumes, cause asphalt binder draindown, and lead to a low asphalt binder content in some mixtures. The objective of this study was to find an asphalt binder or mastic property that can provide appropriate compaction temperatures for use during asphalt mixture design. The data collected in this study strongly suggest that there is not a single viscosity range that can be used for all asphalt binders. It is recommended that the current standardized asphalt binder viscosity range be used for unmodified asphalt binders. For polymer-modified asphalt binders, this study recommends a different viscosity range. The allowable compaction temperature range was based on obtaining an air-void range of 3.5% to 4.5% after each mixture was compacted using the Superpave gyratory compactor. This tolerance provided a relatively wide allowable compaction temperature range. Mechanical properties were not measured. The allowable compaction temperature ranges for these mixtures could be narrower if they were to be based on obtaining the same mechanical properties. Mechanical properties could be more sensitive than density to differences in age-hardening that occur during short-term oven aging and compaction. Additional studies are needed to determine this.

• Record URL:
  • http://www.fhwa.dot.gov/publications/research/infrastructure/pavements/asphalt/pavepubs/02016/index.cfm
• Record URL:
  • https://rosap.ntl.bts.gov/view/dot/56412
• Corporate Authors:

  Federal Highway Administration

  Turner-Fairbank Highway Research Center, 6300 Georgetown Pike
  McLean, VA  United States  22101
• Authors:
  • Stuart, K D
• Publication Date: 2002

Language

• English

Media Info

• Features: References; Tables;
• Pagination: 46 p.

Subject/Index Terms

• TRT Terms: Air voids; Bituminous binders; Compaction; Gyratory testing machines; Polymer asphalt; Temperature; Viscosity
• Subject Areas: Highways; Materials; I31: Bituminous Binders and Materials;

Filing Info

• Accession Number: 00942506
• Record Type: Publication
• Report/Paper Numbers: FHWA-RD-02-016,, Final Report
• Files: NTL, TRIS, USDOT
• Created Date: May 12 2003 12:00AM