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Publication Number: FHWA-HRT-11-021
Date: April 2011

Reclaimed Asphalt Pavement in Asphalt Mixtures: State of The Practice

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ACTION: Distribution of the FHWA RAP in Asphalt Mixtures State of the Practice, FHWA-HRT-11-021

FOREWORD

Recycling asphalt pavement creates a cycle of reusing materials that optimizes the use of natural resources. Reclaimed asphalt pavement (RAP) is a useful alternative to virgin materials because it reduces the need to use virgin aggregate, which is a scarce commodity in some areas of the United States. It also reduces the amount of costly new asphalt binder required in the production of asphalt paving mixtures. This report informs practitioners about the state of the practice for RAP use in the United States as well as best practices for increasing the use of RAP in asphalt pavement mixtures while maintaining high-quality pavement infrastructures. High percentage RAP mixtures are achieved with processing and production practices, resulting in cost and energy savings. Based on an evaluation of pavements containing 30 percent RAP through the Long-Term Pavement Performance (LTPP) program, it has been determined that the performance of pavements containing up to 30 percent RAP is similar to that of pavements constructed from virgin materials with no RAP. This report is of interest to engineers, contractors, and others involved in the specification and design of asphalt mixtures for flexible pavements, as well as those involved in promoting the optimal use of RAP.

Peter Stephanos
Jorge E. Pagán-Ortiz
Director, Office of Pavement Technology
Director, Office of Infrastructure Research and Development

 

Notice

This document is disseminated under the sponsorship of the U.S. Department of Transportation 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.

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.

Technical Report Documentation Page

1. Report No.

FHWA-HRT-11-021

2. Government Accession No. 3. Recipient’s Catalog No.

4. Title and Subtitle

Reclaimed Asphalt Pavement in Asphalt Mixtures: State of the Practice

5. Report Date

April 2011

6. Performing Organization Code

C-00053

7. Author(s)

Audrey Copeland

8. Performing Organization Report No.

9. Performing Organization Name and Address

Office of Infrastructure Research and Development
Federal Highway Administration
6300 Georgetown Pike
McLean, VA 22101

10. Work Unit No. (TRAIS)

11. Contract or Grant No.

12. Sponsoring Agency Name and Address

Turner-Fairbank Highway Research Center
Federal Highway Administration
6300 Georgetown Pike
McLean, VA 22101-2296

13. Type of Report and Period

14. Sponsoring Agency Code

15. Supplementary Notes

The Contracting Officer's Technical Representative (COTR) was Audrey Copeland, HRDI-10.

16. Abstract

With increased demand and limited aggregate and binder supply, hot mix asphalt (HMA) producers discovered that reclaimed asphalt pavement (RAP) is a valuable component in HMA. As a result, there has been renewed interest in increasing the amount of RAP used in HMA. While a number of factors drive the use of RAP in asphalt pavements, the two primary factors are economic savings and environmental benefits. RAP is a useful alternative to virgin materials because it reduces the use of virgin aggregate and the amount of virgin asphalt binder required in the production of HMA. Using RAP greatly reduces the amount of construction debris going into landfills, and it does not deplete nonrenewable natural resources such as virgin aggregate and asphalt binder. Ultimately, recycling asphalt creates a cycle of reuse that optimizes the use of natural resources and sustains the asphalt pavement industry.

 

More widespread use of higher amounts of RAP in asphalt mixtures requires support from State transportation departments and the HMA industry. State transportation departments have expressed concern over the lack of guidance on the use of high percentages of RAP (high RAP) mixtures, as well as the lack of information on their performance. As a result, there is a need for national guidance on best practices when using RAP and documented information about long-term performance of high RAP pavements.

 

The intent of this report is to provide state-of-the-practice information on including higher amounts of RAP in asphalt mixtures. The state of the practice for RAP use across the United States, as well as common challenges for increasing the use of RAP, are identified. Best practices applicable for the use of RAP are presented to identify general parameters that must be considered when developing specifications and to provide information on available resources and best practices for sourcing, processing, stockpiling, testing, designing, evaluating, producing, and placing high RAP mixtures, as well as practices to attain the best performance for high RAP mixtures.

17. Key Words

Reclaimed asphalt pavement (RAP), Recycled asphalt, Hot mix asphalt (HMA), Asphalt mixtures, Superpave®, Performance

18. Distribution Statement

No restrictions. This document is available to the public through the National Technical Information Service, Alexandria, VA 22312.

19. Security Classif. (of this report)

Unclassified

20. Security Classif. (of this page)
Unclassified

21. No. of Pages

55

22. Price

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

SI* (Modern Metric) Conversion Factors

TABLE OF CONTENTS

CHAPTER 1. INTRODUCTION

CHAPTER 2. STATE OF THE PRACTICE FOR RAP USE

CHAPTER 3. BEST PRACTICES FOR INCREASING RAP USE

CHAPTER 4. CONCLUSIONS AND RECOMMENDATIONS

ACKNOWLEDGEMENTS

REFERENCES

LIST OF FIGURES

LIST OF TABLES

ABBREVIATIONS AND SYMBOLS LIST

Abbreviations

AASHTOAmerican Association of State Highway and Transportation Officials
ACAsphalt content
AMPTAsphalt mixture performance tester
BSGBulk specific gravity
CaltransCalifornia Department of Transportation
CDOTColorado Department of Transportation
DOTDepartment of Transportation
DSRDynamic shear rheometer
ESALEquivalent single axle load
ETGExpert task group
FHWAFederal Highway Administration
HMAHot mix asphalt
IRIInternational roughness index
JMFJob mix formula
LTPPLong-Term Pavement Performance
MTOMinistry of Transportation of Ontario
NAPANational Asphalt Pavement Association
NCATNational Center for Asphalt Technology
NCDOTNorth Carolina Department of Transportation
NCHRPNational Cooperative Highway Research Program
ODOTOhio Department of Transportation
PGPerformance grade
QCQuality control
RAPReclaimed asphalt pavement
RTFORolling thin film oven
SCDOTSouth Carolina Department of Transportation
VMAVoids in the mineral aggregate
WMAWarm mix asphalt

 

Symbols

ARAP percent binder content
BRAP percent in mixture
CTotal percent binder content in mixture
|E*|Mix dynamic modulus
G*Shear modulus
GbAsphalt specific gravity
G subscript sb superscript RAP. Bulk specific gravity of RAP aggregate
G subscript se superscript RAP.Effective specific gravity of RAP aggregate
G subscript mm superscript RAP.Maximum theoretical specific gravity of the RAP mixture
PbAsphalt content of the RAP mixture
PbaAsphalt absorption
TBlendCritical temperature of blended asphalt binder
Tc(High)Critical high temperature
Tc(Int)Intermediate critical temperature
Tc(Low)Low critical temperature which is the higher of Tc(S) or Tc(m)
Tc(m)Critical low temperature based on m-value
Tc(S)Critical low temperature based on s-value
TRAPCritical temperature of recovered RAP binder
TvirginCritical temperature of virgin asphalt binder

 


The Federal Highway Administration (FHWA) is a part of the U.S. Department of Transportation and is headquartered in Washington, D.C., with field offices across the United States. is a major agency of the U.S. Department of Transportation (DOT).
The Federal Highway Administration (FHWA) is a part of the U.S. Department of Transportation and is headquartered in Washington, D.C., with field offices across the United States. is a major agency of the U.S. Department of Transportation (DOT). Provide leadership and technology for the delivery of long life pavements that meet our customers needs and are safe, cost effective, and can be effectively maintained. Federal Highway Administration's (FHWA) R&T Web site portal, which provides access to or information about the Agency’s R&T program, projects, partnerships, publications, and results.
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