MIXING TIME REQUIREMENTS FOR BITUMINOUS MIXES AS DETERMINED BY THE ROSS COUNT METHOD

TESTS WERE PERFORMED TO DETERMINE THE PRACTICALITY OF USING THE ROSS COUNT METHOD OF MEASURING AGGREGATE COATING IN ESTABLISHING A MINIMUM WET MIXING TIME FOR BITUMINOUS-CONCRETE MIXTURES. THE RESULTING EFFECTS OF REDUCED MIXING TIMES ON THE MIXTURE PROPERTIES WERE MEASURED BY MARSHALL TESTS. A PRELIMIMARY STUDY WAS CONDUCTED IN THE LABORATORY BEFORE BEGINNING FIELD STUDY WHICH CONSISTED OF ROSS COUNT AND MARSHALL PROPERTY TESTS ON BITUMINOUS-CONCRETE SURFACE MIXTURES PRODUCED FROM SIX HOT-MIX BATCH PLANTS. CRUSHED GRAVEL AGGREGATE WAS IN FOUR OF THE MIXTURES AND CRUSHED LIMESTONE IN THE OTHER TWO. AN 85-100 PENETRATION GRADE ASPHALT CEMENT WAS USED IN ALL MIXTURES. FIVE SAMPLES WERE OBTAINED AND TESTED FOR ROSS COUNT FOR ANY GIVEN WET MIXING TIME AND AT LEAST THREE WET MIXING TIMES WERE USED AT EACH PLANT. DUPLICAT MARSHALL SPECIMENS WERE FORMED IN THE FIELD FOR EACH OF THREE SAMPLES OBTAINED FOR ANY GIVEN WET MIXING TIME. IT WAS FOUND THE THE ROSS COUNT METHOD WAS A SIMPLE AND PRACTICAL PROCECURE TO USE IN TH FIELD WITH THE RELIABILITY OF RESULTS DEPENDENT ON THE EXPERIENCE AND CARE OF THE OPERATOR. STATISTICAL EVALUATION OF THE TEST RESULTS INDICATE THAT THE RELIABILITY OF ANY ONE ROSS COUNT DECREASES AS THE MIXING TIME DECREASES. MARSHALL TEST RESULTS INDICATE THE MIXTURE PROPERTIES OF ALL SIX MIXTURES WERE NOT SIGNIFICANTLY AFFECTED WHEN THE WET MIXING TIME WAS REDUCED TO PERMIT 97 PERCENT AGGREGATE COATING. IT IS CONCLUDED THAT THE PRACTICAL APPROACH OFFERED BY THE ROSS COUNT METHOD COULD BE USED TO ESTABLISH AND CONTROL SATISFACTORILY MINIMUM MIXING TIME REQUIREMENTS.

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 1-22
  • Monograph Title: Bituminous materials, mixtures and pavements
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00214428
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Nov 18 2003 12:00AM