EVALUATION OF VOIDS IN THE MINERAL AGGREGATE FOR HMA PAVING MIXTURES

This study was undertaken to (a) reexamine the rationale behind the minimum voids in the mineral aggregate (VMA) values currently being used, and (b) quantify the relationship between various asphalt film thicknesses and the aging characteristics of the hot mix asphalt (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 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 8% air void content. The minimum VMA required to accommodate this optimum asphalt film thickness and 4% air void content was also calculated.

  • Record URL:
  • Corporate Authors:

    National Center for Asphalt Technology

    Auburn University, 277 Technology Parkway
    Auburn, AL  United States  36830
  • Authors:
    • Kandahl, P S
    • Chakraborty, S
  • Publication Date: 1996-3

Language

  • English

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 38 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00724578
  • Record Type: Publication
  • Report/Paper Numbers: NCAT 96-4
  • Files: NTL, TRIS
  • Created Date: Aug 15 2001 12:00AM