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Publication Number:  FHWA-HRT-17-059    Date:  August 2018
Publication Number: FHWA-HRT-17-059
Date: August 2018


Characterizing Existing Asphalt Concrete Layer Damage for Mechanistic Pavement Rehabilitation Design

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This report presents findings from an analysis of Long-Term Pavement Performance program data. This analysis was undertaken to verify and propose enhancements to the existing overlay design procedure using the Mechanistic-Empirical Pavement Design Guide (MEPDG) rehabilitation design methodology.(1,2)

Deflection data are used to characterize the structural condition of flexible pavements and provide a benchmark in determining the in-place damage of asphalt concrete (AC) layers for use with the MEPDG.(1,2) In-place damage is defined by the ratio of the backcalculated elastic layer modulus and laboratory-measured dynamic modulus of AC layers. This procedure, however, was not verified as part of the MEPDG approach.

The purpose of this report is to document the results from comparing the amount of fatigue cracking to the in-place damage estimated through a modulus ratio between backcalculated elastic modulus values and laboratory-measured dynamic modulus values. The audience for this report includes pavement researchers as well as practicing engineers using AASHTOWare® Pavement ME Design software for rehabilitation design.(3,4)

Cheryl Allen Richter, Ph.D., P.E.
Director, Office of Infrastructure
Research and Development


This document is disseminated under the sponsorship of the U.S. Department of Transportation (USDOT) in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document.

The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers’ names appear in this report only because they are considered essential to the objective of the document.

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Technical Report Documentation Page

1. Report No.


2. Government Accession No.


3 Recipient's Catalog No.


4. Title and Subtitle

Characterizing Existing Asphalt Concrete Layer Damage for Mechanistic Pavement Rehabilitation Design

5. Report Date

August 2018

6. Performing Organization Code


7. Author(s)

Dinesh Ayyala, Hyung Lee, and Mr. Harold L. Von Quintus

8. Performing Organization Report No.


9. Performing Organization Name and Address

Applied Research Associates, Inc.
100 Trade Centre Boulevard, Suite 200
Champaign, IL 61820

10. Work Unit No. (TRAIS)


11. Contract or Grant No.


12. Sponsoring Agency Name and Address

U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Ave., SE
Washington, DC 20500

13. Type of Report and Period Covered

Draft Final Report; September 2014–July 2016

14. Sponsoring Agency Code


15. Supplementary Notes

The Contracting Officer’s Representative was Mr. Larry Wiser (HRDI-30).

16. Abstract

Designing rehabilitation strategies for flexible pavements exhibiting various types and levels of distress is a challenge. An important factor related to the design of a rehabilitation strategy is the use of a reliable procedure to evaluate the
in-place condition of pavements. A project-level pavement evaluation program should consist of multiple activities to assess structural condition, identify the types of pavement deterioration, and determine the cause of deficiencies that need to be addressed during pavement rehabilitation.

One of the critical steps for evaluating the in-place structural condition of existing pavement layers is deflection-basin testing. Deflection basins are used to backcalculate the elasticlayer modulus of existing asphalt concrete (AC) layers, which is considered input level 1 for rehabilitation designs in accordance with the Mechanistic-Empirical Pavement Design Guide.(1) Most agencies measure deflection basins as part of their pavement evaluation programs, but few actually use the data to determine the in-place condition of the AC layers. Deflection data are used to establish analysis sections and/or estimate the resilient modulus of the subgrade soils. However, more recently, agencies have started to use the backcalculated elastic layer modulus to determine the amount of in-place fatigue damage in the existing AC layers.

This report evaluates the use of deflection-basin data to determine the in-place structural condition of AC layers for rehabilitation design in accordance with the Mechanistic-Empirical Pavement Design Guide—A Manual of Practice.(2) A common use of deflection data is to backcalculate in-place layered elastic modulus values.

17. Key Words

Asphalt concrete, Fatigue damage, Backcalculation, Deflection data, Elastic modulus, Falling weight deflectometer, Long-Term Pavement Performance, Mechanistic-Empirical Pavement Design Guide, Pavement evaluation

18. Distribution Statement

No restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161

19. Security Classification
(of this report)


20. Security Classification
(of this page)


21. No. of Pages


22. Price


Form DOT F 1700.7 (8-72) Reproduction of completed page authorized




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