DEVELOPMENT OF A LABORATORY DURABILITY TEST FOR ASPHALTS

A LABORATORY TEST PROCEDURE FOR EVALUATING THE DURABILITY OF PAVING ASPHALTS IS PROPOSED WHICH RECOGNIZES AND IS INTENDED TO SIMULATE THE TWO-STAGE HARDENING OF ASPHALT DURING MIXING PROCESSES AND SUBSEQUENT PAVEMENTS SERVICE LIFE. THE TEST CONSISTS OF FIRST SUBJECTING THE ASPHALT TO THE THIN FILM OVEN TEST (TFOT) AND THEN TREATING THE RESIDUE IN OXYGEN AT HIGH PRESSURES. THE TFOT AT 325 F IS TO SIMULATE THE CHANGES THAT MAY OCCUR IN ASPHALT DURING HOT- MIXING AND THE PRESSURE-OXIDATION PROCESS AT 150 F IS TO SIMULATE THE CHANGES THAT MAY OCCUR IN ASPHALT DURING PAVEMENT SERVICE LIFE. A 1/8-IN. FILM THICKNESS IS USED IN BOTH TREATMENTS. THE EFFECTIVENESS OF THE PROPOSED TEST IN ACCELERATING THE HARDENING AND OTHER CHANGES OF ASPHALT, THE ABILITY OF THE TEST IN DIFFERENTIATING ASPHALTS WITH RESPECT TO CHANGES (BOTH PHYSICAL AND CHEMICAL), AND THE EFFECTS OF TIME AND OXIDATION PRESSURE ARE DEMONSTRATED BY RESULTS OF THE PROPOSED DURABILITY TEST ON FIVE 85-100 PENETRATION GRADE ASPHALT CEMENTS AND ONE OF 120-150 PENETRATION GRADE. THE PROPERTIES MEASURED TO INDICATE CHANGES INCLUDE PENETRATION, SOFTENING POINT, ABSOLUTE VISCOSITY, ASPHALTENE CONTENT, AND PERCENT OXYGEN. THE MAJOR CONCLUSIONS FROM THIS STUDY ARE THAT (1) THE APPROACH OF THE PROPOSED DURABILITY TEST IS SOUND AND THE PROCEDURE REPRODUCIBLE, (2) THE PROCEDURE IS CAPABLE OF ACCELERATING THE HARDENING OF ASPHALT IN A RELATIVELY SHORT PERIOD OF TIME, (3) DIFFERENCES EXIST AMONG ASPHALTS IN HARDENING DURING THE PRESSURE-OXIDATION PROCEDURE, AND THEREFORE THE PROCEDURE CAN DISTINGUISH BETWEEN ASPHALTS THAT ARE SUSCEPTIBLE TO HARDENING AND THOSE THAT ARE NOT, (4) THE HARDENING IN THE PRESSURE-OXIDATION PROCESS IS A HYPERBOLIC FUNCTION OF TIME, WHICH SUGGESTS THAT A DEFINITE CORRELATION CAN BE ESTABLISHED BETWEEN FIELD HARDENING AND THE PROPOSED LABORATORY DURABILITY TEST, AND (5) CONTINUED STUDY INTO THE NEXT PHASE OF THE DURABILITY TEST INVESTIGATION IS NECESSARY AND WARRANTED SO THAT INFORMATION OBTAINED CAN BE PUT INTO USEFUL AND APPLIED FORM IN ASPHALT PAVING DESIGN AND QUALITY CONTROL. /AUTHOR/

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 34-49
  • Monograph Title: Physical factors affecting the durability of asphaltic pavements
  • Serial:

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Filing Info

  • Accession Number: 00211348
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Oct 14 1994 12:00AM