CHANGES IN ASPHALT CEMENTS DURING PREPARATION, LAYING AND SERVICE BITUMINOUS PAVEMENTS

A TWO-YEAR STUDY WAS CONDUCTED COOPERATIVELY BY THE TEXAS TRANSPORTATION INSTITUTE AND THE TEXAS HIGHWAY DEPARTMENT TO DETERMINE THE CHANGES THAT OCCUR IN ASPHALT BINDERS DURING THE PREPARATION, LAYING AND SERVICE OF HOT-MIXED PAVEMENT SURFACES. ASPHALT CEMENTS OF 85-100 PENETRATION GRADE FROM 9 PRODUCERS WERE STUDIED. BITUMEN FROM 4 REFINERIES WERE EACH USED AT TWO DIFFERENT SITES. DURING THE PREPARATION OF EACH PAVING MIXTURE, A SAMPLE OF THE ASPHALT CEMENT FLOWING TO THE HOT-MIX PLANT WAS OBTAINED, FOLLOWED BY SAMPLES OF MIXTURE ENTERING THE TRUCK AND AGAIN AT THE PAVING MACHINE. A SLAB WAS CUT FROM THE PAVEMENT ONE DAY AFTER LAYING AND COMPACTING AND ADDITIONAL SLABS WERE TAKEN AFTER TWO WEEKS, FOUR MONTHS, ONE YEAR AND TWO YEARS OF SERVICE. THE SLABS ON ARRIVAL FROM THE PAVING SITES WERE IMMEDIATELY TESTED FOR DENSITY AND PERMEABILITY TO AIR IN THE LABORATORY. EACH ORIGINAL AND RECOVERED ASPHALT WAS TESTED FOR VISCOSITY AT 77, 95, 140, AND 275 F. DUCTILITIES WERE MEASURED IN THE CALIFORNIA MICRO-DUCTILITY MACHINE AT 77 F. ASPHALTENE CONTENTS WERE DETERMINED ON ORIGINAL ASPHALTS AND RECOVERED SAMPLES AFTER 1 AND 2 YEARS OF SERVICE. DATA SHOW THAT A SMALL INCREASE IN VISCOSITY OCCURS DURING THE PREPARATION OF A PAVING MIXTURE AT TEMPERATURES OF 250-325 F, LAYING THE SURFACING, AND DURING THE FIRST TWO WEEKS OF SERVICE. FROM THEN ON UP TO TWO YEARS THE HARDENING OF ASPHALT PROCEEDS MUCH MORE RAPIDLY. THE INCREASE IN VISCOSITY VARIES AMONG THE DIFFERENT ASPHALTS COMBINED WITH DIFFERENT AGGREGATES UNDER VARIOUS SERVICE CONDITIONS. FOR EACH ASPHALT IT WAS FOUND THAT THE HIGHEST DUCTILITY VALUE AT 77 F WAS ALWAYS ASSOCIATED WITH A VISCOSITY OF 1 TO 3 MEGAPOISES AT 77 F. THE ASPHALTENE CONTENT USUALLY INCREASES, BUT IN A FEW SITUATIONS AN UNEXPLAINED DECREASE IS NOTED. VISCOSITIES OF THE PETROLENES, SEPARATED FROM THE ORIGINAL ASPHALTS AND FROM THE MATERIALS EXTRACTED AFTER TWO YEARS OF SERVICE IN THE PAVEMENT, WERE DETERMINED AT 77 F. OVER THE PERIOD OF TWO YEARS THE PETROLENES INCREASED IN VISCOSITY FROM 1.05 TO 20.1 FOLD. THE INCREASE IN ASPHALTENE CONTENT AND PETROLENE VISCOSITIES AT 77 F WITH TIME DO NOT IN EVERY CASE EXPLAIN THE HARDENING OF THE FILMS OF ASPHALT CEMENT DURING SERVICE.

• Supplemental Notes:
  • Vol 36, pp 541-561, 4 FIG, 9 TAB, 8 REF, 1 APP
• Authors:
  • Traxler, R N
• Conference:
  • Assoc Asphalt Paving Technol Proc
• Publication Date: 1967-2

Subject/Index Terms

• TRT Terms: Asphalt cement; Asphalt pavements; Asphalt tests; Asphaltene; Concrete hardening; Ductility tests; Hardness; Hot mix asphalt; Malthene; Permeability; Properties of materials; Samples; Slabs; Viscosity
• Uncontrolled Terms: Change; Laying
• Old TRIS Terms: Ductility tests (Asphalts); Petrolene component /asphalt/; Viscosity test
• Subject Areas: Highways; Materials;

Filing Info

• Accession Number: 00210721
• Record Type: Publication
• Files: TRIS
• Created Date: May 1 1994 12:00AM