COAL-MODIFIED TAR BINDERS FOR BITUMINOUS CONCRETE PAVEMENTS

THE POSSIBILITY OF MAKING AN IMPROVED BINDER FOR BITUMINOUS PAVEMENTS OF THE HOT-MIX HOT-LAY TYPE BY DISPERSING COAL IN DISTILLED COAL TARS AND COAL TAR OILS IS STUDIED. SUITABLE LABORATORY AND PILOT PLANT EQUIPMENT WAS ASSEMBLED AND OPTIMUM CONDITIONS FOR THE DISPERSION OF COAL IN TARS AND OILS WERE DETERMINED. VARIOUS COALS, TARS, AND OILS WERE COMPARED AS TO THEIR SUITABILITY FOR THE PURPOSE. EXPERIMENTAL QUANTITIES OF COAL-MODIFIED TAR BINDERS WERE PRODUCED AND ANALYZED AND THEN COMBINED WITH VARIOUS AGGREGATES IN HOT MIXES. THE LATTER WERE THEN COMPARED WITH HOT MIXES CONTAINING TYPICAL ASPHALT CEMENTS AND COAL-TAR BINDERS. THE TESTS APPEARED TO INDICATE THAT IT WOULD BE POSSIBLE TO MAKE HOT MIXES WITH COAL-MODIFIED TAR CEMENTS EQUAL OR SUPERIOR TO THOSE MADE WITH USUAL ASPHALT OR COAL- TAR BINDERS. A PILOT PLANT WAS BUILT TO PRODUCE 150,000 GALLONS OF COAL-MODIFIED TAR BINDER FOR COMPARISON WITH ASPHALT CEMENTS NORMALLY USED IN KENTUCKY IN CLASS I AND CLASS I-MODIFIED BITUMINOUS-PAVEMENTS. DURING A PERIOD OF THREE MONTHS IT PRODUCED 104 BATCHES OF BINDER, OF WHICH 100 BATCHES WERE OF THE THREE-COMPONENT TYPE (COAL, TAR, AND OIL), TWO OF THE TWO-COMPONENT TYPE (COAL AND TAR), AND TWO CONSISTED ONLY OF TAR (RT-12). THE BINDER WAS DELIVERED TO 14 TEST SITES IN VARIOUS PARTS OF THE STATE. AT TWO, THREE- COMPONENT BINDER WAS USED IN HOT MIX LAID 2 3/4 INCHES THICK ON A TAR-PRIMED SOIL BASE (CLASS I-MODIFIED). AT ALL OTHER SITES, THE BINDER WAS USED IN 1 1/2 INCH CLASS I OVERLAYS ON EXISTING BLACK-TOP PAVEMENTS WHICH FOR THE MOST PART HAD REQUIRED EXTENSIVE MAINTENANCE BECAUSE OF BASE FAILURES, EXCESSIVE CRACKING, OR THE DEVELOPMENT OF SLIPPERY SURFACES. COAL-MODIFIED TAR BINDERS APPEARED TO BE SOMEWHAT SUPERIOR TO USUAL ASPHALTIC HOT-MIXES WITH RESPECT TO SET-UP DURING ROLLING AND EARLY TRAFFIC, BUT INFERIOR WITH RESPECT TO FUMING, ESPECIALLY WHEN THE TEMPERATURES OF THE MIXES EXCEEDED 260 F. INSPECTION OF SOME OF THE TEST SECTIONS IN SPRING 1960, FOLLOWING UNUSUALLY SEVERE WINTER WEATHER, EMPHASIZED THE NEED FOR BETTER TEMPERATURE SUSCEPTIBILITIES TO PROVIDE GREATER FLEXIBILITY OF THE OVERLAYS AT LOW ATMOSPHERIC TEMPERATURES. COMPARISONS WERE MADE OF THE SUITABILITY OF APPROXIMATELY 40 DIFFERENT COALS FROM VARIOUS PARTS OF THE UNITED STATES AND FOREIGN COUNTRIES, THE USE OF LOW, MEDIUM, AND HIGH-TEMPERATURE TARS AS DISPERSING MEDIA FOR THE COALS, ATTEMPTS TO USE OILS OF PETROLEUM ORIGIN AS FLUXING AGENTS, AND THE ADDITION OF VARIOUS POLYMERS TO THE COAL-DISPERSIONS. ALSO, VARIOUS TYPES OF BINDERS WERE COMPARED AS TO THEIR VISCOSITIES AT SEVERAL TEMPERATURES AND NUMEROUS METHODS FOR COMPARING THE BRITTLENESS OF DIFFERENT HOT-MIX BINDERS AT LOW TEMPERATURES WERE TRIED. /AUTHOR/

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 1-42
  • Monograph Title: Symposium on coal-modified tar binder for bituminous concrete pavements
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00210827
  • Record Type: Publication
  • Files: TRIS, TRB, ATRI
  • Created Date: Jun 3 1994 12:00AM