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https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

FATIGUE OF ASPHALT PAVEMENT MIXES

STIFFNESS PLAYS A PREDOMINANT ROLE IN DETERMINING THE FATIGUE PERFORMANCE OF ASPHALT MIXES. THIS IS CONSIDERED IN RELATION TO THE DIFFERENT TYPE OF FATIGUE TESTS GENERALLY USED AND TO ITS EFFECT ON CRACK PROPAGATION AS WELL AS CRACK INITIATION. THE IMPORTANT FACTORS OF BITUMEN CONTENT AND VOIDS CONTENT ARE ALSO DISCUSSED. THE EXPERIMENTAL WORK REPORTED IS CHIEFLY CONCERNED WITH THE FATIGUE PROPERTIES OF ACTUAL ASPHALT MIXES AS USED IN PRACTICE. SPECIMENS OF BOTH WEARING AND BASECOURSE MIXES AT VARIOUS TEMPERATURES WERE TESTED UNDER CONSTANT AMPLITUDE BENDING STRESS. DIFFERENT STONE CONTENTS AND GRADINGS OF BOTH GRAVEL AND CRUSHED ROCK AGGREGATE WERE USED WITH A MAXIMUM SIZE OF AGGREGATE OF 3/4 INCH. THE MAJORITY OF MIXES TESTED COMPLIED WITH THE SPECIFICATION FOR ROLLED ASPHALT AS USED ON THE ROADS OF GREAT BRITAIN. THE RESULTS CONFIRMED THE EARLIER CONCLUSION THAT FATIGUE CRACK INITIATION WAS PRIMARILY CONTROLLED BY THE MAGNITUDE OF THE APPLIED TENSILE STRAIN AND THUS EMPHASISED THE IMPORTANCE OF MEASURING THE ACTUAL STIFFNESS UNDER THE SAME CONDITIONS OF TEMPERATURE AND LOADING AS APPLY IN THE FATIGUE TESTS. MEASUREMENTS OF DYNAMIC STIFFNESS UNDER THESE CONDITIONS SHOWED ITS DEPENDENCE ON STRESS AMPLITUDE. THE TYPE OF AGGREGATE WHETHER GRAVEL OR CRUSHED GRANITE, AND THE GRADING DO NOT GREATLY INFLUENCE THE LIFE EXCEPT IN SO FAR AS THESE FACTORS EFFECT THE STIFFNESS. THE ADDITION OF SOME FILLER TO MIXES WHICH NORMALLY CONTAIN NONE RESULTS IN LONGER FATIGUE LIVES AND THE TESTS ALSO EMPHASISED THE IMPORTANCE OF THE BITUMEN CONTENT, AN OPTIMUM VALUE BEING APPARENT. THIS ADDED SUPPORT TO THE HYPOTHESIS THAT FATIGUE LIFE DEPENDS ON THE STRAIN IN THE BINDER PRESENT IN THE MIX. THE GRADE OF BITUMEN EFFECTS THE FATIGUE LIFE NOT ONLY BY ALTERING THE STIFFNESS OF THE MIX BUT ALSO THROUGH ITS INFLUENCE ON THE SLOPE OF THE FATIGUE LINE. MIXES MADE WITH A 90/110 PEN. BITUMEN HAVING A STEEPER LINE THAN THOSE MADE WITH A 40/50 PEN. BITUMEN. FROM THE FATIGUE STRENGTH ASPECT IT APPEARS THAT THERE IS SOME ADVANTAGE IN USING A MIX HAVING A HIGHER CONTENT OF A LOWER PENETRATION BITUMEN THAN IS USUAL WITH A CONTINUOUSLY GRADED AGGREGATE. /AUTHOR/

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Filing Info

  • Accession Number: 00210670
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Sep 15 1994 12:00AM