TRANSVERSE CRACKING OF FLEXIBLE PAVEMENTS IN SASKATCHEWAN- PHASE 2: AGE-HARDENING OF SASKATCHEWAN ASPHALT CEMENTS

A CONSISTENT FEATURE OF ASPHALTIC CONCRETE PAVEMENTS IN SASKATCHEWAN IS CLOSELY SPACED TRANSVERSE CRACKS WHICH ON SECTIONS WITH EXPANSIVE SUBGRADE SOILS LEAD TO SEVERE TRANSVERSE RIDGING AND ON OTHER SECTIONS TO SEVERE DEPRESSIONS AT THE CRACKS THROUGH EROSION OF UNDERLYING GRANULAR SOILS. SHRINKAGE CRACKS ARE LESS A PROBLEM THAN ARE CRACKS RESULTING FROM EXPANSION--CONTRACTION CHARACTERISTICS OF THE ASPHALTIC CONCRETE. IN 1963 FULL-SCALE IN-SERVICE TEST SECTIONS WERE BUILT TO STUDY THIS PHENOMENON. THESE SECTIONS EXHIBITED A SIGNIFICANT RELATIONSHIP BETWEEN FREQUENCY OF CRACKS AND ASPHALT SOURCE. AS A RESULT, SPECIFICATIONS FOR ASPHALT CEMENT WERE MADE MORE STRINGENT. IN 1966 AN INVESTIGATION WAS INITIATED TO DETERMINE WHETHER THE AGING CHARACTERISTICS OF THE NEW ASPHALTS AFFECTED THE FREQUENCY OF TRANSVERSE CRACKING. ASPHALTS FROM FOUR SUPPLIERS WERE SAMPLED FROM FIVE TEST SECTIONS THROUGHOUT THE FIRST 36 MONTHS OF SERVICE. CHANGES IN PENETRATION AND VISCOSITY AND IN TEMPERATURE AND SHEAR SUSCEPTIBILITY WERE COMPARED AGAINST CALCULATED STIFFNESS VALUES AND AGAINST THE NUMBER OF TRANSVERSE CRACKS. THE PRINCIPAL CONCLUSION TO EMERGE WAS THAT ALTHOUGH IN-SERVICE AGING INCREASED STIFFNESS, PUGMILLING ALONE PROVIDED THE ASPHALTS SUFFICIENT STIFFNESS FOR TRANSVERSE CRACKING OF THE PAVEMENTS AT TYPICAL LOW IN-SERVICE TEMPERATURES.

  • Supplemental Notes:
    • 4 APP
  • Corporate Authors:

    Saskatchewan Dept Hwys, Regina /Canada

    ,    
  • Authors:
    • CULLEY, R W
  • Publication Date: 1972-5

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 37 p.
  • Serial:
    • Issue Number: tr16

Subject/Index Terms

Filing Info

  • Accession Number: 00207479
  • Record Type: Publication
  • Files: TRIS, ATRI
  • Created Date: Feb 3 1973 12:00AM