DETECTING VARIATIONS IN LOAD-CARRYING CAPACITY OF FLEXIBLE PAVEMENTS

A RESEARCH STUDY WAS CONDUCTED TO DETERMINE THE FEASIBILITY OF DETECTING SEASONAL VARIATIONS IN THE LOAD- CARRYING CAPACITY OF FLEXIBLE PAVEMENTS BY USING AN IMPULSIVE LOADING TECHNIQUE. THE APPLICABILITY OF IMPULSIVE LOADING TECHNIQUES WAS ESTABLISHED BY DROPPING A BAR ONTO A STRIKER PLATE AND MEASURING THE VERTICAL DYNAMIC DISPLACEMENT OF THE PAVEMENT, THE REBOUND TIME OF THE BAR, THE DURATION OF CONTACT BETWEEN THE BAR AND THE STRIKER PLATE /IMPULSE DURATION/, AND THE WAVE PROPAGATION TIME. A METHOD OF CORRELATING THE IMPULSIVE LOADING TECHNIQUE WITH A STATIC LOADING TECHNIQUE FOR AN IDEALIZED ELASTIC HALF-SPACE WAS DEVELOPED. FOR THE MEASUREMENT OF PROPAGATION TIME IT WAS DECIDED TO USE COMMERCIAL VELOCITY PICKUPS AND A RECORDING OSCILLOGRAPH, WITH A BUILT-IN TIMING MECHANISM. A SERIES OF FIELD TESTS WAS CONDUCTED ON A TEST ROAD DESIGNATED A POOR ROAD WHICH WAS AN OLD POORLY-DRAINED FLEXIBLE PAVEMENT ON WHICH LOAD RESTRICTIONS ARE REGULARLY IMPOSED AND ON A GOOD ROAD WHICH WAS A NEWLY-BUILT ROAD WITHOUT LOAD RESTRICTIONS. THESE TESTS SHOWED A SEASONAL VARIATION OF ABOUT 70 PERCENT IN THE DYNAMIC DISPLACEMENT TRANSDUCER FIRST PEAK DEFLECTION FOR THE POOR ROAD AND A SLIGHTLY HIGHER PERCENTAGE FOR THE CORRECTED DEFLECTION /A MEASURE OF ABSOLUTE DISPLACEMENT/. THE TESTS ALSO SHOWED THE POOR ROAD DEFLECTION TO BE ABOUT 2 1/2 TIMES AS LARGE AS THAT OF THE GOOD ROAD. THE REBOUND TIME AND IMPULSE DURATION SHOWED RESULTS THAT REFLECTED SEASONAL VARIATIONS. IT IS CONCLUDED THAT THE IMPULSIVE LOADING TECHNIQUE IS A FEASIBLE METHOD OF DETECTING SEASONAL VARIATIONS IN THE LOAD-CARRYING CAPACITY OF FLEXIBLE PAVEMENTS, THE FIRST PEAK DEFLECTION INDICATED BY THE DYNAMIC DISPLACEMENT TRANSDUCER BEING THE MOST PROMISING VARIABLE TO BE MEASURED.

  • Availability:
  • Supplemental Notes:
    • No. 21, 30 PP, 26 FIG, 4 TAB, 17 REF, 3 APP
  • Authors:
    • Isada, N M
  • Publication Date: 1966

Media Info

  • Serial:
    • NCHRP Report
    • Issue Number: 21
    • Publisher: Transportation Research Board
    • ISSN: 0077-5614

Subject/Index Terms

Filing Info

  • Accession Number: 00206249
  • Record Type: Publication
  • Files: TRIS, ATRI
  • Created Date: Dec 12 1994 12:00AM