PENETRATION AND VISCOSITY FUNCTIONS IN BITUMINOUS CONCRETE

THREE EXPERIMENTAL PROJECTS, EACH APPROXIMATELY FOUR MILES IN LENGTH, WERE RESURFACED WITH ASPHALT CONCRETE. DIFFERENT GRADES AND TYPES OF ASPHALTS VARYING BETWEEN 60 AND 150 PENETRATION, WITH VISCOSITIES RANGING FROM 885 TO 3198 POISES AT 140 F WERE USED. FIVE TO EIGHT DIFFERENT ASPHALTS WERE USED IN EACH PROJECT. ONE TYPE AGGREGATE ONLY, LIMESTONE, GRAVEL, OR CRUSHED SAND WAS USED IN AN INDIVIDUAL PROJECT. THE OBJECTIVE OF THESE EXPERIMENTAL PROJECTS WAS TO DETERMINE VISCOSITY-PENETRATION RELATIONSHIPS, PROPERTIES AND BEHAVIOR OF THE ASPHALT CEMENTS, FUNCTIONS OF VISCOSITY AND PENETRATION IN MIXING, ROLLING AND COMPACTION, AND EVALUATION OF THE DURABILITY OF EACH ASPHALT. IN ONE PROJECT WHERE A WELL GRADED ANGULAR LIMESTONE WAS USED, NO DIFFICULTY WAS ENCOUNTERED, IN LAYING AND COMPACTION REGARDLESS OF THE TYPE OF ASPHALT WHEN THE MIXING WAS ACCOMPLISHED AT 300 F. IN THE PROJECT WHERE GRAVEL WAS USED, THE GRAVEL AND ASPHALT WERE EASILY MIXED AT 300 F. HOWEVER, DIFFICULTY WAS EXPERIENCED IN COMPACTING SOME OF THE MIXTURES AND IT WAS NECESSARY TO ADJUST THE MIX TEMPERATURE TO THE PROPER VISCOSITY IN ORDER TO USE THE DIFFERENT ASPHALTS. IN THE SAND-ASPHALT MIX PROJECT, MIXING TEMPERATURES HAD TO BE ADJUSTED TO ELIMINATE TEARING OF THE ONE MIXTURE CONTAINING ONE OF THE ASPHALTS AND THE TENDERNESS OF THE OTHER DURING LAYDOWN AND COMPACTION. DEPENDING ON THE TYPE OF AGGREGATE IT WAS SHOWN THAT THE VISCOSITY, AND NOT THE PENETRATION, OF THE ASPHALT GOVERNED THE MIXING, LAYING AND COMPACTION OPERATIONS. TESTS WERE CONDUCTED ON THE ORIGINAL ASPHALTS AND ON ASPHALTS EXTRACTED FROM THE MIX AT THE PUGMILL, BEHIND THE PAVER, COMPACTED ROADWAY, AND PERIODIC ROADWAY SAMPLES. RESULTS DISCLOSED THAT ASPHALTENES AND VISCOSITY INCREASED, AND PENETRATION AND DUCTILITY DECREASED IN VALUE WITH TIME. THE ASPHALTS USED IN THE SAND MIX ARE HARDENING AT A FASTER RATE THAN IN THE OTHER TWO JOBS. THE INDIVIDUAL ASPHALTS ARE HARDENING AT DIFFERENT RATES AND SOME OF THE ASPHALTS HAVE NO DUCTILITY AT LOW TEMPERATURES. HOWEVER, VISUAL OBSERVATIONS SHOWED THAT ALL OF THE SURFACES ARE PERFORMING EXCELLENTLY. PERIODIC INVESTIGATIONS OF THE EFFECTS OF THE DIFFERENT ASPHALTS ON DURABILITY IS PROGRAMMED. /AUTHOR/

  • Supplemental Notes:
    • Hpr-1/4/, BPR-5
  • Corporate Authors:

    Pennsylvania Department of Highways

    400 North Street
    Harrisburg, PA  USA  17120-0095

    Bureau of Public Roads /US

    400 7th Street, SW
    Washington, DC  USA  20590
  • Authors:
    • Sandvig, L D
    • Kofalt, J A
  • Publication Date: 1967-8

Subject/Index Terms

Filing Info

  • Accession Number: 00210388
  • Record Type: Publication
  • Source Agency: Bureau of Public Roads /US
  • Files: TRIS
  • Created Date: Apr 2 1994 12:00AM