CURRENT STATUS OF THE EQUIVALENCY RATIO PROBLEM

THE EQUIVALENCY RATIO RATING IS PRESUMED TO SHOW THE RELATIVE STRESS DISTRIBUTION CHARACTERISTIC OF A MATERIAL AS A PAVEMENT LAYER PER UNIT OF THICKNESS, WHICH IS USUALLY TAKEN AS ONE INCH. DURING THE LAST SEVERAL YEARS THE USE OF THE EQUIVALENCY CONCEPT IS BEING ADVOCATED BY SEVERAL ORGANIZATIONS INTERESTED IN ASPHALT PRODUCTION AND RESISTED BY SEVERAL ORGANIZATIONS INTERESTED IN CRUSHED STONE PRODUCTION. THE AUTHOR FEEL THAT THE USE OF ASSIGNED EQUIVALENCY RATIOS TO VARIOUS TYPES OF BASE COURSE MATERIALS BOTH STABILIZED AND UNSTABILIZED, IS ARBITRARY AND IGNORES SOUND PRINCIPLES OF ENGINEERING EVALUATION OF BASE COURSE MATERIALS AS THEY BEHAVE IN PAVEMENTS. RECENT TESTS AND DEVELOPMENTS ARE REPORTED ON EQUIVALENCY RATIO EXPERIENCE. BASED ON THE STOCKTON TESTS, THE EQUIVALENCY RATIO WOULD BE SLIGHTLY IN FAVOR OF CRUSHED STONE. THE SHARONVILLE OVERLAY TEST TRACK RESULTS SHOW NO APPRECIABLE DIFFERENCE IN THE TYPE OF OVERLAY USED. THE OVERLAY COMPOSED OF ALL ASPHALTIC CONCRETE PERFORMED THE SAME AS AN OVERLAY COMPOSED OF AN ASPHALTIC CONCRETE SURFACE COURSE WITH EITHER A WATERBOUND MACADAM BASE, BLACK BASE, OR CRUSHED STONE BASE, THE KENTUCKY FLEXIBLE PAVEMENT DESIGN CRITERIA RESEARCH REPORT STATES THAT THE THE TERM LAYER EQUIVALENCE IS INAPPROPRIATE AND INCONSISTENT WITH CONCEPTS OF DESIGN. THE SURVEY CONCLUDES THAT: (1) THE LABORATORY TEST DEVELOPMENT AND COMPUTATIONAL TECHNIQUES ARE ADVANCED OVER EXPERIMENTAL PROTOTYPE TESTING, (2) THERE IS A DEARTH OF PROPERLY DESIGNED AND CONSTRUCTED COMPARATIVE EXPERIMENTAL PROTOTYPE TESTING BETWEEN TREATED AND UNTREATED BASES AND SUBBASES, AND (3) UNTIL SUCH TESTING IS ACCOMPLISHED TO ESTABLISH UNQUESTIONED EQUIVALENCY RATIOS, THE PAVEMENT DESIGN ENGINEER SHOULD CONTINUE TO UTILIZE HIS BEST ENGINEERING TESTING AND JUDGMENT IN EVALUATION OF THE MATERIALS INVOLVED IN SPECIFIC PAVEMENT DESIGNS.

  • Supplemental Notes:
    • Vol 6, No 23, PP 16-17, 43-45, 47, 49, 51, 21 REF
  • Authors:
    • Turnbull, W J
  • Publication Date: 0

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Filing Info

  • Accession Number: 00232829
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jun 1 1970 12:00AM