HARDENING OF ASPHALT CEMENTS DURING SERVICE IN PAVEMENTS 1963-66 PROGRAM

AN INVESTIGATION IS DESCRIBED WHICH DETERMINES THE CHANGES IN HARDENING AND COMPOSITION THAT OCCUR IN AN ASPHALT CEMENT WHILE THE HOT MIXTURE IS BEING PREPARED AND LAID AND DURING SERVICE IN THE PAVEMENT. SEVENTEEN TESTS SITES WERE SELECTED WHEREBY HOT SURFACINGS COULD BE LAID. IMMEDIATELY PRIOR TO ARRIVAL OF THE PAVING MACHINE, 20 FEET OF HEAVY ALUMINUM FOIL WAS FASTENED TO THE ROAD SURFACE BY ROOFING NAILS. THIS WAS DONE TO PREVENT CONTAMINATION OF THE APPLIED HOT MIXTURE BY THE TACK COAT AND TO FACILIATE REMOVAL OF THE PAVEMENT SAMPLES FOR EXTRACTION, RECOVERY AND TESTING OF THE ASPHALTIC BINDER. ONE DAY AFTER LAYING AND COMPACTING THE SURFACE, A 2- BY 2-FOOT SAMPLE OF THE PAVEMENT WAS REMOVED AND SHIPPED TO THE INSTITUTE IN A WODDEN BOX DESIGNED TO PREVENT BREAKAGE DURING SHIPMENT. SIMILAR SAMPLES WERE OBTAINED AFTER THE PAVEMENT HAD BEEN IN SERVICE FOR PERIODS OF 2 WEEKS, FOUR MONTHS, 1 YEAR, AND FOR 9 OF THE SITES AFTER 3 YEARS IN SERVICE. THE SAMPLES OF PAVING MIXTURES AND THE SLABS OF PAVEMENT SAMPLES WERE SUBJECTED TO LABORATORY EVALUATION AND THE ASPHALT EXTRACTED USING 6 PARTS OF BENZENE AND 1 PART OF PURE ETHYL ALCOHOL. EXTRACTED ASPHALT WAS CAREFULLY RECOVERED FROM SOLUTION AND SUBJECTED TO NUMEROUS TESTS. RELATIVE VISCOSITY, WHICH IS OBTAINED BY DIVIDING THE VISCOSITY OF AN ASPHALT HARDENED BY ENVIRONMENTAL AND SERVICE CONDITIONS BY ITS ORIGINAL VISCOSITY, IS USEFUL FOR COMPARING THE HARDENING OF AN ASPHALT OR DIFFERENT ASPHALTS UNDER DIFFERENT ENVIRONMENTAL CONDITIONS. CAREFUL PREPARATION, HANDLING AND LAYING OF THE HOT MIXTURES RESULTED IN 1.55 TO 2.80 FOLD INCREASE IN VISCOSITY AT 77F OF THE RECOVERED ASPHALT WITH RESPECT TO ORIGINAL BINDER. AFTER THREE YEARS OF SERVICE IN PAVEMENTS, THE INCREASE IN VISCOSITY OF THE RECOVERED ASPHALT RANGED FROM 13.5 TO 41.5 FOLD. HARDENING OF THE ORIGINAL ASPHALT BY THE LABORATORY TEST GAVE ABOUT THE SAME HARDENING AS RESULTED FROM TWO WEEKS IN SERVICE. SEASON OF THE YEAR IN WHICH THE PAVEMENT WAS LAID, THE HVEEM STABILITY TESTS AND THE COHESIVE TESTS APPEAR TO HAVE ONLY SMALL EFFECTS ON THE CONDITIONS OF THE HIGHWAY SURFACE AFTER TWO OR THREE YEARS OF SERVICE. HIGH AVERAGE DAILY TRAFFIC COUNT APPEARS TO BE ASSOCIATED WITH A PAVEMENT SURFACING SHOWING EXCELLENT TO GOOD CONDITION AFTER TWO TO THREE YEARS IN SERVICE. DATA OBTAINED INDICATE THAT THE AGGREGATE USED IN CONSTRUCTION OF A PAVEMENT SURFACE MAY INFLUENCE HARDENING OF THE ASPHALT DURING SERVICE. ASPHALTENE CONTENTS OF THE BINDERS EXTRACTED FROM THE PAVEMENTS AFTER TWO YEARS OF SERVICE WERE GREATER THAN FOR THE ORIGINAL ASPHALTS. OXYGEN CONTENTS OF ORIGINAL AND EXTRACTED ASPHALTS WERE DETERMINED BY NEUTRON ACTIVATION ANALYSIS, AND WERE FOUND TO BE HIGHER THAN THE ASPHALTS AFTER FOUR MONTHS IN SERVICE THAN IN THE ORIGINAL ASPHALTS. HOWEVER, THE OXYGEN DROPPED SLIGHTLY AFTER THE PAVEMENT HAD BEEN IN SERVICE ONE YEAR.

  • Supplemental Notes:
    • Progress RpT NO 11, PP 1-46, 8 FIG, 11 TAB, 1 APP
  • Corporate Authors:

    Texas Transportation Institute

    Texas A&M University System, 1600 E Lamar Boulevard
    Arlington, TX  United States  76011

    Texas State Department of Highways & Public Transp

    11th and Brazos Streets
    Austin, TX  United States  78701
  • Authors:
    • Traxler, R N
  • Publication Date: 1967-10

Subject/Index Terms

Filing Info

  • Accession Number: 00210824
  • Record Type: Publication
  • Files: TRIS, STATEDOT
  • Created Date: Jun 3 1994 12:00AM