'SETTING' AND DURABILITY STUIDES ON PAVING GRADE ASPHALTS

THE ESSENTIAL ENGINEERING PROPERTIES OF PAVING ASPHALT ARE: (1) CONSISTENCY, (2) RATE OF CURING OR SETTING, (3) DURABILITY, AND (4) RESISTANCE TO WATER ACTION. THE AC SERIES OF ASPHALTS PRODUCED TO MEET THE NEW PROPOSED ASPHALT INSTITUTE GRADING LIMITS BASED ON VISCOSITY AS 140 F, MEASURED IN ABSOLUTE UNITS (POISES) WERE STUDIED. ANOTHER GROUP OF ASPHALTS WERE USED IN THE TEST PROGRAM, WHICH WERE COMPOSED OF FORTY 85-100 GRADE PAVING ASPHALTS FOR THE 1954- 55 BUREAU OF PUBLIC ROADS TEST SERIES. CHANGES DURING MIXING WERE STUDIED USING THE AASHO THIN FILM OVEN TEST AND THE CALIFORNIA ROLLING THIN FILM TEST. A SATISFACTORY CORRELATION WAS FOUND FOR RESULTS OBTAINED BY BOTH METHODS. SPECIFICATION REQUIREMENTS TO PROVIDE PROPER SETTING ARE PRESENTED BASED ON CONTROLLING GRADE AND SETTING PROPERTIES BY SPECIFYING VISCOSITY RANGES IN ABSOLUTE UNITS AT 140 F AND 275 F ON RESIDUE FROM THE CALIFORNIA THIN FILM TEST. THESE REQUIREMENTS WILL INSURE AN ASPHALT WITH MORE UNIFORM CONSISTENCY IN THE PAVING MIXTURE. TESTS SIMULATING PAVEMENT SERVICE LIFE WERE PERFORMED ON THE TWO GROUPS OF THE ASPHALT SAMPLES. THE FORTY 85-100 GRADE PAVING ASPHALTS WERE SUBJECTED TO INFRARED WEATHERING IN AN OVEN FOR 1000 HOURS, EQUIVALENT TO AT LEAST FIVE YEARS SERVICE LIFE AND IN A MODIFIED THIN FILM OVEN TEST FOR DURABILITY REQUIREMENTS IN TENTATIVE SPECIFICATIONS. STUDIES OF PROPERTY CHANGES DURING WEATHERING INDICATE THAT THESE ASPHALTS MAY BE DIVIDED INTO GROUPS. SOME OF THE ASPHALTS WEATHER VERY RAPIDLY FROM VOLATILIZATION AND CHEMICAL CHANGES WHILE OTHERS WEATHER QUITE SLOWLY AS MEASURED BY CHANGING CONSISTENCY BUT THE SHEAR SUSCEPTIBILITY CHANGES VERY RAPIDLY WITH A RAPID DROP IN DUCTILE PROPERTIES. THE RESULTS INDICATE THAT THE ASPHALTS WEATHER IN DIFFERENT WAYS AND COULD PRESENT DIFFERENT FORMS OF PAVEMENT FAILURE. SPECIFICATION TESTS INDICATE THAT A MOST IMPORTANT PROBLEM IN ASPHALT SPECIFICATION REQUIREMENTS IS THE DETERMINATION OF THE MAXIMUM AMOUNT OF SHEAR SUSCEPTIBILITY THAT MAY DEVELOP IN A PAVING GRADE ASPHALT PRIOR TO PAVEMENT FAILURE.

• Supplemental Notes:
  • Vol 36, pp 387-420, 13 FIG, 9 TAB, 19 REF
• Authors:
  • Skog, J
• Conference:
  • Assoc Asphalt Paving Technol Proc
• Publication Date: 1967-2

Subject/Index Terms

• TRT Terms: Asphalt; Asphalt content; Asphalt pavements; Bituminous mixtures; Concrete curing; Consistency; Durability; Infrared radiation; Oven tests; Pavement performance; Service life; Shear strength; Simulation; Thin films; Viscosity; Weathering
• Uncontrolled Terms: Thin film oven test
• Subject Areas: Design; Highways; Materials;

Filing Info

• Accession Number: 00210718
• Record Type: Publication
• Files: TRIS
• Created Date: May 1 1994 12:00AM