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.
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- Find a library where document is available. Order URL: http://worldcat.org/issn/00775614
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Supplemental Notes:
- Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved. No. 21, 30 PP, 26 FIG, 4 TAB, 17 REF, 3 APP
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Authors:
- Isada, N M
- Publication Date: 1966
Media Info
- Media Type: Digital/other
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Serial:
- NCHRP Report
- Issue Number: 21
- Publisher: Transportation Research Board
- ISSN: 0077-5614
Subject/Index Terms
- TRT Terms: Bars (Building materials); Bearing capacity; Deflection; Dislocation (Geology); Experimental roads; Field tests; Flexible pavements; Impulses (Mechanics); Loads; Measurement; Oscillographs; Pavements; Rebound; Recording; Seasons; Static loads; Transducers; Velocity; Waves
- Uncontrolled Terms: Loading; Seasonal variations
- Old TRIS Terms: Bearing capacities; Impulses; Pavement deflection; Propagation; Static loading
- Subject Areas: Highways; Pavements;
Filing Info
- Accession Number: 00206249
- Record Type: Publication
- Files: TRIS, ATRI
- Created Date: Dec 12 1994 12:00AM