VARIABILITY IN MEASURED DEFLECTIONS AND BACKCALCULATED MODULI FOR THE STRATEGIC HIGHWAY RESEARCH PROGRAM SOUTHERN REGION
It is well known that excessive variability in subgrade characteristics, layer thicknesses, material characteristics, and other such construction variables are major causes of distress and loss of performance in pavements. As the use of deflection measurements to characterize pavement structural capacity and to determine the elastic moduli of the separate layers increases, variability in the deflection measurements and the resulting estimates of the elastic moduli become more important. One study reported was intended as a preliminary evaluation of the amount of variability in deflections that may be expected in relatively short test sections (500 ft for the Strategic Highway Research Program test sections studies), and to learn what characteristics of pavements contribute to this variability. The relative causes of the variability were studied using correlations of variations in deflections with various characteristics of the pavements, such as layer thicknesses, layer stiffnesses, and asphalt viscosity. These studies indicate that the typical coefficients of variation for deflections range between 4 and 18% of the mean deflections, but some coefficients of variation for specific test sections will run over 40% of the mean deflections. A second study identified variations in backcalculated moduli for four test sections. This limited set of backcalculated moduli indicates that variability in backcalculated moduli for base layers is much higher than that for the asphalt concrete (AC) layers and subgrade and that the coefficients of variation for backcalculated AC moduli appear to be proportional to those for measured deflections. Some causes of the variability appear to have been identified, but variability in deflection measurements were found to result from a multitude of pavement characteristics, each resulting in minor effects to create the whole.
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Availability:
- Find a library where document is available. Order URL: http://worldcat.org/isbn/0309054206
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Supplemental Notes:
- This paper appears in Transportation Research Record No. 1377, Nondestructive Deflection Testing and Backcalculation for Pavements, Proceedings of a Symposium, August 19-21, 1991, Nashville, Tennessee. 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
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Authors:
- Rauhut, J Brent
- Jordahl, Peter R
- Publication Date: 1992
Language
- English
Media Info
- Features: Figures; References; Tables;
- Pagination: p. 45-56
- Monograph Title: Nondestructive deflection testing and backcalculation for pavements: proceedings of a symposium, August 19-21, 1991, Nashville, Tennessee
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Serial:
- Transportation Research Record
- Issue Number: 1377
- Publisher: Transportation Research Board
- ISSN: 0361-1981
Subject/Index Terms
- TRT Terms: Asphalt concrete; Backcalculation; Base course (Pavements); Deflection; Layer coefficient (Pavements); Measurement; Modulus; Pavements; Stiffness; Subgrade (Pavements); Test sections; Thickness; Variables; Viscosity
- Identifier Terms: Strategic Highway Research Program
- Uncontrolled Terms: Layer moduli
- Old TRIS Terms: Pavement deflection; Thickness design
- Subject Areas: Data and Information Technology; Design; Highways; Pavements; I22: Design of Pavements, Railways and Guideways; I23: Properties of Road Surfaces;
Filing Info
- Accession Number: 00627239
- Record Type: Publication
- ISBN: 0309054206
- Files: TRIS, TRB
- Created Date: Apr 5 1993 12:00AM