Backcalculation of Asphalt Pavement Properties

Project Title

Backcalculation of in-situ Moduli of Asphalt Pavement Layers using Nondestructive Testing

Research Team

M. Emin Kutay (PI), Sudhir Varma

Abstract

Accurate characterization of pavement layer moduli is important to determine deterioration of highway infrastructure for proper allocation of funds and resources for maintenance and rehabilitation. Nondestructive Falling Weight Deflectometer (FWD) testing is a well-recognized method for evaluating the structural capacity and integrity of highway and airfield pavements. It enables the use of a mechanistic approach for pavement design and rehabilitation by allowing for backcalculating in-situ material properties from the measured field surface deflections through appropriate analysis techniques. However, traditional models utilize layered elastic forward algorithms, which are too simplistic and cannot be used to backcalculate fundamental pavement material properties such as the dynamic modulus (|E*|) master curve and nonlinear properties of unbound layers. In this project, research team investigated methodologies, developed models and algorithms to backcalculate the |E*| mastercurve of the asphalt pavement layer and the nonlinear properties of the unbound layers using the time history of Falling Weight Deflectometer (FWD) surface deflections.

Graph, Photos, etc.

Impact

If the damaged in-situ |E*| mastercurve of the asphalt concrete and the nonlinear properties of the unbound layers in an existing pavement can be obtained from FWD deflections, a more accurate prediction of its remaining service life can be achieved. The key element in the success of any pavement management system responsible for making preventive and corrective decisions is a proper assessment of the present status and an accurate prediction of the future performance of a pavement structure. Characterizing in-situ pavement properties plays a critical role in both activities.

Publications

  1. Varma, S. and Kutay, M. E. “Backcalculation of Viscoelastic and Nonlinear Flexible Pavement Layer Properties from Falling Weight Deflections”, International Journal of Pavement Engineering, in-review.
  2. Varma, S. and Kutay, M. E. “A Viscoelastic Nonlinear Multilayered Model for Asphalt Pavements”, ASCE Journal of Engineering Mechanics. In Press
  3. Varma,S., Kutay, M. E. and Levenberg, E. (2013) “A Viscoelastic Genetic Algorithm for Inverse Analysis of Asphalt Layer Properties from Falling Weight Deflections” Transportation Research Record: Journal of the Transportation Research Board, Vol. 2369, No. 4, pp. 38-46 (DOI: 10.3141/2369-05).
  4. Kutay, M.E., Chatti, K. and Lei, L. (2011) “Backcalculation of Dynamic Modulus from FWD Deflection Data”, Transportation Research Record: Journal of the Transportation Research Board, TRR 2227, Vol. 3, pp. 87-96.
  5. Chatti, K., Kutay, M. E., Lajnef, N., Zaabar, I., Varma, S. and Lee, H.S. (2014) “Enhanced Analysis of Falling Weight Deflectometer Data for use with Mechanistic-Empirical Flexible Pavement Design and Analysis and Recommendations for Improvements to Falling Weight Deflectometer”, FHWA Report, Grant No. DTFH61-11-C-00026.
  6. Varma, S., Kutay, M.E. (2014) “Backcalculation of Viscoelastic and Nonlinear Flexible Pavement Layer Properties from Falling Weight Deflections”, 93rd Annual Transportation Research Board Conference, Washington, D.C., January 12-16, 2014.

Acknowledgements

The funding for this study was provided by FHWA. This support is greatly appreciated. The authors also express their gratitude to Nadarajah (Siva) Sivanesvaran of FHWA for his valuable comments on the analyses presented in this paper.





M. Emin Kutay 2016