Characterization of the Stiffness of Unbound Materials for Pavement Design: Do We Follow the Right Approach?
Publication: Journal of Transportation Engineering
Volume 140, Issue 4
Abstract
Two main approaches have been followed to determine the modulus of unbound materials in six asphalt pavement sections tested at the CEDEX test track. The first one consists on back-calculation from the deflection bowls measured under the load of a falling weight deflectometer. In the second approach, a nonlinear constitutive relationship is calibrated from repeated load triaxial testing, and layer modulus is estimated through this relationship for the stresses calculated under traffic loads by using a multilayer linear elastic model. Significant differences were found between the two procedures, with back-calculation resulting in higher modulus. The two approaches were evaluated by comparing model predictions to actual response measured under the load of the traffic simulation vehicles of the test track. The results indicate that back-calculation provided more realistic estimations of the stiffness of unbound materials than the laboratory approach. This last approach significantly underestimated the stiffness of granular materials located at shallow depths in the pavement structure.
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Acknowledgments
Results presented here come from a full-scale experiment that was funded by the Spanish General Road Directorate. The authors of this paper would like to express their gratitude to this institution.
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Published In
Journal of Transportation Engineering
Volume 140 • Issue 4 • April 2014
Copyright
© 2014 American Society of Civil Engineers.
History
Received: May 21, 2013
Accepted: Nov 7, 2013
Published online: Jan 6, 2014
Published in print: Apr 1, 2014
Discussion open until: Jun 6, 2014
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