UTAH'S USE OF DYNAFLECT DATA FOR PAVEMENT REHABILITATION

DEFLECTION MEASUREMENTS ARE USEFUL IN DETERMINING THE STRUCTURAL ADEQUACY OF PAVEMENTS BEFORE UNDERTAKING RESURFACING OF AN EXISTING PAVEMENT. UTAH IS NOW USING A DRESSER-ATLAS (FORMERLY LANE-WELLS) DYNAFLECT FOR DEFLECTION MEASUREMENTS. THE SYSTEM CONSISTS OF A SMALL TRAILER TOWED BEHIND A VEHICLE WITH A CONTROL UNIT LOCATED IN THE VEHICLE BESIDE THE OPERATOR. THE DYNAMIC DEFLECTION IS MEASURED BETWEEN TWO RIGID STEEL WHEELS THAT ARE SUBJECTED TO AN OSCILLATORY LOAD OF 1,000 LB PEAK-TO-PEAK VARYING SINUSOIDALLY AT THE RATE OF 8 CYCLES PER SECOND. THE MAGNITUDE OF THE DEFLECTIONS ARE SENSED BY MEANS OF 5 GEOPHONES SPACED AT 1-FT INTERVALS BEGINNING WITH ONE PLACED BETWEEN THE FORCE WHEELS. THE SHAPE OF THE DEFLECTION BASIN IS DETERMINED BY UTILIZING THE VALUES FROM ALL GEOPHONES. THE DEFLECTIONS ARE READ ON THE METER IN THE CONTROL UNIT IN THE TOW VEHICLE. THERE IS GOOD CORRELATION BETWEEN THE DATA OBTAINED WITH THE BENKLEMAN BEAM AND THOSE OBTAINED WITH THE DYNAFLECT. PERFORMANCE-DEFLECTION RELATIONSHIPS WERE ESTABLISHED AS PART OF THE AASHO ROAD TEST AND EQUATIONS FOR FALL OR SPRING NORMAL DEFLECTIONS WERE DEVELOPED. THESE EQUATIONS WERE MODIFIED FOR THE DYNAFLECT AND USED TO DEVELOP TWO FAMILIES OF CURVES CORRELATING DYNAFLECT DEFLECTIONS, DAILY EQUIVALENT 18-KIP LOADS, AND PAVEMENT LIFE. THE SURFACING CAN THEN BE DETERMINED FOR REHABILITATION WHICH IS THE AMOUNT REQUIRED TO REDUCE THE ACTUAL DEFLECTION TO THE ALLOWABLE DEFLECTION. DATA ARE PRESENTLY BEING DEVELOPED FOR DETERMINATION OF THE THICKNESS OF A NEW SURFACE COURSE REQUIRED TO REDUCE THE DEFLECTION TO A POINT AT WHICH IT WILL MEET THE DESIGN-LIFE CRITERIA.

• Record URL:
  • http://onlinepubs.trb.org/Onlinepubs/hrr/1969/300/300-003.pdf
• Supplemental Notes:
  • Paper sponsored by Committee on Salvaging Old Pavements by Resurfacing, Maintenance of Bituminous Pavements, and Maintenance of Portland Cement Concrete Pavements and presented at the 48th Annual Meeting. 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.
• Authors:
  • Liddle, W J
  • Peterson, Dale E
• Publication Date: 1969

Media Info

• Media Type: Digital/other
• Features: Figures; References;
• Pagination: pp 10-15
• Monograph Title: Design of overlays and pavement rehabilitation
• Serial:
  • Highway Research Record
  • Issue Number: 300
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Benkelman beam; Deflection tests; Deflectometers; Driver rehabilitation; Dynaflect; Equations; Evaluation; Geophones; Pavement performance; Pavements; Resurfacing; Sensors; Thickness
• Identifier Terms: AASHO Road Test
• Uncontrolled Terms: Rehabilitation
• Geographic Terms: Utah
• Old TRIS Terms: Test results; Thickness design
• Subject Areas: Highways; Maintenance and Preservation; Pavements;

Filing Info

• Accession Number: 00207075
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: Feb 16 1970 12:00AM