REDUCTION OF ASPHALT HARDENING IN SURFACE COURSES OF BITUMINOUS PAVEMENTS

A study is reported which was made in an effort to understand and isolate the important variables involved in pavement distress and to determine ways to eliminate or reduce the most destructive forces. A method was developed to measure the hardening of road asphalt at atmospheric (service) temperatures. Test sites were selected in widely separated areas in Texas. At each field site, the following samples were collected: (1) original asphalt as it entered the hot mix plant, (2) hot asphalt-aggregate as it entered the truck, (3) asphalt-aggregate mixture when it was placed in the paving machine, and (4) 2-ft. x 2 ft. samples of the surface course taken 1 day, 2 weeks, 4 months, 1 years, 2 years and 3 years after pavement was laid and compacted. The studies revealed no satisfactory correlation between the asphalt recovered from a pavement surface after 2 years in service and the hardening obtained from a laboratory thin film test involving only the action of time, heat and air on the original asphalt. The studies indicate that the prime factor responsible for the hardening of the asphalts in surface courses of bituminous pavements is the chemically active (actinic) solar radiation impinging on the pavement surface. The analysis of 64 asphalts for vanadium content revealed a relationship between this metal content and the degree of hardening of each aspahlt subjected to the new test using chemically active solar radiation. Small amounts of different materials blended into asphalts are capable of retarding the hardening of asphalts caused by exposure to time, heat, air and active solar radiation; one proprietory additive, UOP-256 was found to be particularly effective.

  • Supplemental Notes:
    • Proceedings of the meeting held in Houston, Texas, February 1973.
  • Corporate Authors:

    University of Minnesota, Minneapolis

    155 Experimental Engineering Building
    Minneapolis, MN  United States  55455
  • Authors:
    • Traxler, R N
    • Shelby, M D
  • Conference:
  • Publication Date: 1973

Media Info

  • Features: Appendices; Figures; References; Tables;
  • Pagination: p. 126-159
  • Serial:
    • Volume: 42

Subject/Index Terms

Filing Info

  • Accession Number: 00127327
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Dec 16 2000 12:00AM