Evaluation of Voids in the Mineral Aggregate for HMA Paving Mixtures

Details

• Creators:
  Kandhal, Prithvi S. ; Chakraborty, Sanjoy
• Corporate Creators:
  National Center for Asphalt Technology (U.S.)
• Subject/TRT Terms:
  • Hot mix asphalt
  • Asphalt concrete
  • Mineral aggregates
  • Air voids
  • Void ratios
  • Films (Coatings)
  • Durability
  • Aging
  • Asphalt paving mixtures
  • Film thickness
• Publication/ Report Number:
  Report No. 9
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States
• Corporate Publisher:
  National Center for Asphalt Technology (U.S.)
• Abstract:
  This study was undertaken (a) to reexamine the rationale behind the minimum VMA ; values currently being used, and (b) to quanti~ the relationship between various asphalt film thicknesses and the aging characteristics of the HMA mix, so that an optimum film thickness desirable for satisfactory mix durability could be established. The optimum film thickness could then be used to establish VMA requirements. Mixes prepared with asphalt binder film thickness ranging from about 4 to 13 microns, were subjected to accelerated aging using Strategic Highway Research Program (SHRP) procedures to simulate both short and long term aging. Both the aggregate (RD) and the asphalt ?Respectively, Associate Director, National Center for Asphalt Technology, and Graduate Student, Auburn University, Alabama. cement (AAM- 1 ) used in this study were obtained from the SHRP Materials Reference Library. The aged, compacted mix was tested for tensile strength, tensile strain at failure and resilient modulus. The aged asphalt cement was recovered and tested for penetration, viscosity, complex between various asphalt film thicknesses and the aging characteristics of the HMA mix, so that an optimum film thickness desirable for satisfactory mix durability could be established. The optimum film thickness could then be used to establish modulus and phase angle. Aging indices were obtained from these tests, and the relationship between film thickness and the aged mix/aged asphalt cement properties were determined using regression analysis. For the particular aggregate/asphalt cement combination used in this study, it was found that accelerated aging would occur if the asphalt binder film thickness was less than 9- 10 microns in an HMA mixture compacted to 80/0 air void content. The minimum VMA required to accommodate this optimum asphalt film thickness and 40/0 air void content, was also calculated.
• Format:
  PDF
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/13627/dot_13627_DS1.pdf
• File Type:
  [PDF - 302.69 KB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:969aaa2525d883676598b9a628c5e8c900676c8d49b14c5054d52dccb4adec81c946ad0ac43ab6df8da2056dbead0cb5ca41a485d379e4d04f60f31a3413295e