INFLUENCE OF MINERAL AGGREGATE STRUCTURE ON PROPERTIES OF ASPHALT PAVING MIXTURES

MINERAL AGGREGATE, A COMPONENT COMPRISING BY FAR LARGEST PROPORTION OF A PAVING MIXTURE, HAS AN IMPORTANT INFLUENCE ON THE PERFORMANCE OF ASPHALT PAVEMENTS. VISUAL EXAMINATION OF GRAVEL OR CRUSHED ROCK ALMOST ALWAYS REVEALS THE VARIABLE AXIAL DIMENSIONS OF INDIVIDUAL PARTICLES. DURING COMPACTION THE LONG AXES OF AGGREGATE PARTICLES TEND TO ALIGN PERPENDICULARLY TO THE FORCE OF COMPACTION. THIS ALIGNMENT CAUSES ANISOTROPIC STRENGTHS IN DIFFERENT DIRECTIONS OF COMPACTED ASPHALT MIXTURES. THE PURPOSE OF THIS PAPER IS TO EVALUATE THE MAGNITUDE OF SUCH ANISOTROPIC BEHAVIOR. TEST CUBES, CUT FROM ASPHALTIC CONCRETE SPECIMENS AND COMPACTED BY THE CONVENTIONAL LABORATORY METHODS, WERE TESTED FOR COMPRESSIVE STRENGTH IN THE DIRECTIONS NORMAL AND PARALLEL TO THE FORCE OF COMPACTION. THE RATIO OF THE MEASURED DIRECTIONAL STRENGTH /I.E., STRUCTURAL INDEX/ WAS USED TO ASSESS THE DEGREE OF PARTICLE ALIGNMENT OR STRUCTURE AS INFLUENCED BY THE SHAPE CHARACTERISTICS OF AGGREGATE, CONSISTENCY OF ASPHALT, AND TYPE OF COMPACTION. FURTHERMORE, AN ATTEMPT WAS MADE TO EVALUATE THE EFFECTS OF THE SECONDARY FACTORS, SUCH AS RATE OF LOADING, DEGREE OF COMPACTION, AND AGGREGATE GRADATION, ON THE STRUCTURAL INDEX. A LIMITED NUMBER OF TESTS ON SPECIMENS CUT FROM ACTUAL PAVEMENTS WAS ALSO INCLUDED IN THIS TESTING PROGRAM. THESE TESTS INDICATED THAT THE DIRECTIONAL STRENGTHS OF THE CUBE-SHAPED SPECIMENS ALWAYS VARIED, REGARDLESS OF WHETHER THEY CONTAINED NATURAL ROUNDED GRAVEL OR CRUSHED ANGULAR ROCK. IT WAS EVIDENT THAT THE STRUCTURE OR SHAPE OF THE AGGREGATE AND TYPE OF COMPACTION INFLUENCED THE ANISOTROPY OF THE COMPACTED ASPHALT CONCRETE TO A GREAT DEGREE. HOWEVER, THE EFFECTS OF FACTORS SUCH AS CONSISTENCY OF ASPHALT TEST TEMPERATURE, OR RATE OF LOADING WERE ALSO PRONOUNCED. THESE LABORATORY TESTS SUGGEST JUSTIFICATION OF FIELD TRIALS EVALUATING THE EFFECTS OF AGGREGATE PARTICLE ALIGNMENT ON THE RHEOLOGICAL BEHAVIOR OR LOAD TRANSFER PROPERTIES OF PAVEMENT STRUCTURES. /AUTHOR/

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 1-18
  • Monograph Title: Bituminous concrete mixtures and construction
  • Serial:

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Filing Info

  • Accession Number: 00210268
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Dec 12 1994 12:00AM