SUPERIOR PERFORMING ASPHALT PAVEMENT

SUPERPAVEPerformance by Design

F I N A L R E P O RT O F T H E T R B S U P E R PAV E C O M M I T T E E

TRANSPORTATION RESEARCH BOARD EXECUTIVE COMMITTEE 2005 (Membership as of October 2005)

O F F I C E R S

Chair: John R. Njord, Executive Director, Utah DOT

Vice Chair: Michael D. Meyer, Professor, School of Civil and Environmental Engineering, Georgia Institute of Technology

Executive Director: Robert E. Skinner, Jr., Transportation Research Board

M E M B E R S

MICHAEL W. BEHRENS, Executive Director, Texas DOT

ALLEN D. BIEHLER, Secretary, Pennsylvania DOT

LARRY L. BROWN, SR., Executive Director, Mississippi DOT

DEBORAH H. BUTLER, Vice President, Customer Service, Norfolk Southern Corporation and Subsidiaries, Atlanta, GA

ANNE P. CANBY, President, Surface Transportation Policy Project, Washington, DC

JOHN L. CRAIG, Director, Nebraska Department of Roads

DOUGLAS G. DUNCAN, President and CEO, FedEx Freight, Memphis, TN

NICHOLAS J. GARBER, Professor of Civil Engineering, University of Virginia, Charlottesville

ANGELA GITTENS, Vice President, Airport Business Services, HNTB Corporation,, Miami, FL

GENEVIEVE GIULIANO, Director, Metrans Transportation Center, and Professor, School of Policy, Planning, and Development, USC, Los Angeles

BERNARD S. GROSECLOSE, JR., President and CEO, South Carolina State Ports Authority

SUSAN HANSON, Landry University Professor of Geography, Graduate School of Geography, Clark University

JAMES R. HERTWIG, President, CSX Intermodal, Jacksonville, FL

GLORIA JEAN JEFF, Director, Michigan DOT

ADIB K. KANAFANI, Cahill Professor of Civil Engineering, University of California, Berkeley

HERBERT S. LEVINSON, Principal, Herbert S. Levinson Transportation Consultant, New Haven, CT

SUE MCNEIL, Professor, Department of Civil and Environmental Engineering, University of Delaware, Newark

MICHAEL R. MORRIS, Director of Transportation, North Central Texas Council of Governments

CAROL A. MURRAY, Commissioner, New Hampshire DOT

MICHAEL S. TOWNES, President and CEO, Hampton Roads Transit, Hampton, VA

C. MICHAEL WALTON, Ernest H. Cockrell Centennial Chair in Engineering, University of Texas, Austin

LINDA S. WATSON, Executive Director, LYNX-Central Florida Regional Transportation Authority

MARION C. BLAKEY, Federal Aviation Administrator, U.S.DOT (ex officio)

JOSEPH H. BOARDMAN, Federal Railroad Administrator, U.S.DOT (ex officio)

REBECCA M. BREWSTER, President and COO, American Transportation Research Institute, Smyrna, GA (ex officio)

GEORGE BUGLIARELLO, Chancellor, Polytechnic University, and Foreign Secretary, National Academy of Engineering (ex officio)

J. RICHARD CAPKA, Acting Administrator, Federal Highway Administration, U.S.DOT (ex officio)

THOMAS H. COLLINS (Adm., U.S. Coast Guard), Commandant, U.S. Coast Guard (ex officio)

JENNIFER L. DORN, Federal Transit Administrator, U.S.DOT (ex officio)

JAMES J. EBERHARDT, Chief Scientist, Office of FreedomCAR and Vehicle Technologies, U.S. Department of Energy (ex officio)

JACQUELINE GLASSMAN, Deputy Administrator, National Highway Traffic Safety Administration, U.S.DOT (ex officio)

EDWARD R. HAMBERGER, President and CEO, Association of American Railroads (ex officio)

JOHN C. HORSLEY, Executive Director, American Association of State Highway and Transportation Officials (ex officio)

JOHN E. JAMIAN, Acting Administrator, Maritime Administration, U.S.DOT (ex officio)

EDWARD JOHNSON, Director, Applied Science Directorate, National Aeronautics and Space Administration (ex officio)

ASHOK G. KAVEESHWAR, Research and Innovative Technology Administrator, U.S.DOT (ex officio)

BRIGHAM MCCOWN, Deputy Administrator, Pipeline and Hazardous Materials Safety Administration, U.S.DOT (ex officio)

WILLIAM W. MILLAR, President, American Public Transportation Association (ex officio)

SUZANNE RUDZINSKI, Director, Transportation and Regional Programs, U.S. Environmental Protection Agency (ex officio)

ANNETTE M. SANDBERG, Federal Motor Carrier Safety Administrator, U.S.DOT (ex officio)

JEFFREY N. SHANE, Under Secretary for Policy, U.S.DOT (ex officio)

CARL A. STROCK (Maj. Gen., U.S. Army), Chief of Engineers and Commanding General, U.S. Army Corps of Engineers (ex officio)

SUPERIOR PERFORMING ASPHALT PAVEMENT

SUPERPAVEPerformance by Design

F I N A L R E P O RT O F T H E T R B S U P E R PAV E C O M M I T T E E

ii SUPERPAVE: PERFORMANCE BY DESIGN

Transportation Research Board Miscellaneous Report

ISBN 0-309-09414-3

Transportation Research Board publications are available by ordering individual publications directly from the TRB Business Office, throughthe Internet at www.TRB.org or www.national-academies.org/trb, or by annual subscription through organizational or individual affiliationwith TRB. Affiliates and library subscribers are eligible for substantial discounts. For further information contact the Transportation ResearchBoard Business Office, 500 Fifth Street, NW, Washington, DC 20001 (telephone 202-334-3213; fax 202-334-2519; or e-mail TRBsales@nas.edu).

Copyright 2005 by the National Academy of Sciences. All rights reserved. Printed in the United States of America.

NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose mem-bers are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and Institute of Medicine. Themembers of the committee responsible for the report were chosen for their special competencies and with regard for appropriate balance.

This report has been reviewed by a group other than the authors according to the procedures approved by a Report Review Committee con-sisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine.

This project was sponsored by the Federal Highway Administration of the U.S. Department of Transportation and the NationalCooperative Highway Research Program.

iii

This report draws on many sources. The committee wishes especially to acknowledgewritten contributions from E. Ray Brown, Director, National Center for Asphalt

Technology at Auburn University; Rebecca McDaniel, Technical Director, North CentralSuperpave Center, Purdue University; and Paul J. Mack, Deputy Chief Engineer, New YorkState DOT (retired), whose energies and commitment have long served the TRB SuperpaveCommittee.

Under the guidance of the TRB Superpave Committee and the Expert Task Group onCommunications, the report was drafted by Neil F. Hawks, Director, Special ProgramsDivision, TRB, and by Linda Mason, Communications Manager, who also edited the reportand managed its design and production.

This report has been reviewed in draft form by individuals chosen for their diverse perspec-tives and technical expertise, in accordance with procedures approved by the NRC’s ReportReview Committee. The purpose of this independent review is to provide candid and criticalcomments that will assist the institution in making its published report as sound as possibleand to ensure that the report meets institutional standards for objectivity, evidence, andresponsiveness to the study charge. The review comments and draft manuscript remain confi-dential to protect the integrity of the deliberative process. We wish to thank the following indi-viduals for their review of this report:

E. Dean Carlson, Carlson Associates, Topeka, Kansas; Raymond K. Moore, University ofNebraska, Lincoln, College of Engineering and Technology, Omaha, Nebraska; and Freddy L.Roberts, Louisiana Technology University, Ruston, Louisiana.

Although the reviewers listed above have provided many constructive comments and sugges-tions, they were not asked to endorse the conclusions or recommendations nor did they see thefinal draft of the report before its release. The review of this report was overseen by C. MichaelWalton, University of Texas at Austin. Appointed by the National Research Council, he wasresponsible for making certain that an independent examination of this report was carried outin accordance with institutional procedures and that all review comments were carefully con-sidered. Suzanne Schneider, Associate Executive Director of TRB, managed the report reviewprocess. Responsibility for the final content of this report rests entirely with the authoringcommittee and the institution.

v

ACKNOWLEDGEMENTS

vii

MEMBERS OF THE TRB SUPERPAVE COMMITTEE

CHAIRMANJoseph A. MickesAbsorption Systems, Inc.

MEMBERSDavid A. AndersonProfessor of Civil EngineeringPennsylvania State University

Martin F. BarkerPavement & Materials EngineerCity of AlbuquerquePublic Works Department

Jed S. Billings (served through2004)President and Chief ExecutiveOfficerFNF Construction, Inc.

Frank L. DanchetzChief EngineerGeorgia Dept. of Transportation

Fred M. Fehsenfeld, Sr.Chairman of ExecutiveCommitteeThe Heritage Group

John E. HaddockAssistant Professor of CivilEngineeringPurdue University

Eric E. HarmEngineer of Materials andPhysical ResearchIllinois Dept. of Transportation

Paul J. MackDeputy Chief Engineer/Director,Technical Services DivisionNew York State Dept. ofTransportation

Charles R. MarekPrincipal Materials EngineerVulcan Materials Company

John B. MetcalfFreeport-McMoRan Professor ofEngineeringLouisiana State University

Gale C. PageState Flexible PavementMaterials EngineerFlorida Dept. of Transportation

Douglas R. RoseDeputy Administrator/ChiefEngineer for OperationsMaryland State HighwayAdministration

Byron E. Ruth (served through2004)Professor, Civil EngineeringUniversity of Florida

Dean C. WeitzelChief Materials EngineerNevada Dept. of Transportation

J.T. YarnellChief EngineerMissouri Dept. of Transportation

LIAISONSDave E. NewcombVice President-Research andTechnologyNational Asphalt PavementAssociation

Ken F. KobestkyProgram Director, EngineeringAmerican Association of StateHighway and TransportationOfficials

Bernard M. McCarthyVice PresidentThe Asphalt Institute

Tommy BeattyDirector, Office of PavementTechnologiesFederal HighwayAdministration, HIPT

Sarah Wells Program Manager, C-SHRPTransportation Association ofCanada

Greg SmithManaging Director, Contractor’sDivisionAmerican Road &Transportation BuildersAssociation

TRB STAFFNeil F. HawksDirector, Special Programs

CONSULTANTTed FerragutTDC Partners, Ltd.

CHAIRMANJames A. Musselman State Bituminous EngineerFlorida Department ofTransportationState Materials Office

VICE CHAIRMANJames Winford, Jr.PresidentLouisiana Road and Bridge Co., Inc.

MEMBERSJimmy W. Brumfield Mississippi DOT (Retired)

Ervin L. Dukatz, Jr.Vice President, Materials andResearchMathy Construction Company

Gary S. Ferguson Consultant

Karl Frick Pavement Materials EngineerCalifornia Dept. ofTransportation

Kevin D. Hall ProfessorUniversity of Arkansas

Adam J.T. Hand Quality Systems EngineerGranite Construction, Inc.

Lon S. Ingram Chief, Bureau of Materials &ResearchKansas Department ofTransportation

Y. Richard Kim,ProfessorNorth Carolina State UniversityDept. of Civil Engineering

Cynthia LaFleur Quality Control ManagerCallanan Industries

Todd A. Lynn ManagerAPAC, Inc., Materials Services

Wade McClay Quality Acceptance SupervisorMaine Department ofTransportation

Judie Ryan Engineering SpecialistWisconsin Department ofTransportation

John Weigel, Jr.Corporate Technical ServicesManagerPayne and Dolan, Inc.

LIAISONR. Michael AndersonDirector of ResearchAsphalt Institute

John R. BukowskiSenior Asphalt PavementEngineerFederal Highway Administration

Eric E. HarmEngineer of Materials PhysicalResearchIllinois Department ofTransportation

F.M. “Rick” HarveyState Materials EngineerWyoming Department ofTransportation

Charles R. MarekPrincipal Materials EngineerVulcan Materials Company

David E. NewcombVice President-Research andTechnologyNational Asphalt PavementAssociation

TRB STAFF Edward HarriganTransportation Research Board

Neil F. HawksTransportation Research Board

Fred HejlTransportation Research Board

CONSULTANTTed FerragutTDC Partners, Ltd.

EXPERT TASK GROUP FOR SUPERPAVE MIXTURES AND AGGREGATES

viii

EXPERT TASK GROUP FOR SUPERPAVE ASPHALT BINDER TECHNOLOGY

EXPERT TASK GROUP FOR SUPERPAVE COMMUNICATION AND TRAINING

CHAIRMANDouglas R. RoseDeputy Administrator/ChiefEngineer of OperationsMaryland State HighwayAdministration

MEMBERSE. Ray Brown,DirectorNational Center for AsphaltTechnologyAuburn University

Gary J. HainesChevron Corporation

Robert LudwigDirector, ExternalCommunicationsGraduate ManagementAdmissions Council

Paul J. MackConsultant

Joe P. MahoneyProfessor of Civil EngineeringUniversity of WashingtonDepartment of Civil Engineering

Mansour SoulaimanianPennsylvania State University

FRIENDS OF THE ETGMargaret Blaine CervarichCommunications DirectorNational Asphalt PavementAssociation

Donald W. LucasDirector of Government AffairsThe Heritage Group

FHWA LIAISONS:Thomas P. HarmanAsphalt Pavement Team LeaderFederal Highway AdministrationTurner Fairbank Research Center

FRIENDS OF THE ETGGloria BurkeMaryland State HighwayAdministration

Woodrow HoodMaryland State HighwayAdministration

TRB STAFFLinda MasonCommunications ManagerSpecial Programs DivisionTransportation Research Board

Neil HawksDirectorSpecial Programs DivisionTransportation Research Board

CONSULTANTTed Ferragut, PETDC Partners, Ltd.

CHAIRMANJohn H. Tenison State Materials Bureau ChiefNew Mexico Department ofTransportation

VICE CHAIRMANGaylon Baumgardner Executive Vice PresidentParagon Technical Service, Inc.

MEMBERSHussain Bahia Associate ProfessorUniversity of Wisconsin -Madison

Darren G. Hazlett Supervising Chemical EngineerConstruction Division -MaterialsTexas Department ofTransportation

Richard J. Holmgreen Manager, Asphalt TechnicalSupportConocoPhillips

Mihai Marsteanu University of Minnesota

Dean A. Maurer Bituminous Testing EngineerPennsylvania Department ofTransportation

Gerald H. Reinke PresidentMTE Services, Inc.

Geoffrey M. Rowe PresidentAbatech, Inc.

Eileen C. Sheehy Manager, Bureau of MaterialsNew Jersey DOT

Thomas J. Snyder Manager, Asphalt TechnologyMarathon Ashland Petroleum,LLC

Peter Wu Bituminous Control EngineerGeorgia Department ofTransportation

LIAISONJohn D’AngeloFHWAAsphalt Materials EngineerFederal HighwayAdministration

David A. AndersonProfessor of Civil EngineeringPenn State UniversityPenn Transportation Institute

Kenneth H. NeumillerMaterials Bureau ChiefMontana Department ofTransportation

Gale C. PageState Bituminous MaterialsEngineerFlorida Department ofTransportationState Materials Office

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

CHAPTER 1

CURRENT STATUS OF SUPERPAVE IMPLEMENTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Use by County and Municipal Roads Agencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Establishing Costs and Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Uniformity in Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

CHAPTER 2

MEETING THE R&D GOALS OF SUPERPAVE DEVELOPMENT AND DEPLOYMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Integration R&D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

New Research. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

CHAPTER 3

FROM EXOTIC TO EVERYDAY: Looking Back at the Technology Transfer Challenge . . . . . . 25

Implementation Drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Training and Technology Transfer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

CONTENTS

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CHAPTER 4

UNANSWERED QUESTIONS: A Need for Continuous Improvement . . . . . . . . . . . . . . . . . . 31

Moisture Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Integration with Pavement Design Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Mineral Aggregate Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Asphalt Modification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Superpave for Local Roads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

History of Superpave . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

A Successful Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Reference List. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Committee Member Biographical Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Superpave®, a principal product of the Strategic Highway Research Program, is a system ofstandard specifications, test methods, and engineering practices that enable the appropri-

ate materials selection and mixture design of hot mix asphalt to meet the climatic and trafficconditions of specific roadway paving projects. Through use of this system, highway engineersand constructors can build pavements that last longer, require less maintenance and have alower life-cycle cost than pavements designed using previous engineering methods.

The origin of Superpave can be traced back to 1984 and the Transportation Research Board’s(TRB) publication of Special Report 202, America’s Highways: Accelerating the Search forInnovation. The committee that authored this report concluded that, despite its dominantposition among highway materials, research into asphalt cement or binder had been long neg-lected and a strategically focused research program could “develop improved asphalt binders.”Building from the recommendations offered by Special Report 202, in 1986, the AmericanAssociation of State Highway and Transportation Officials (AASHTO) released recommendedresearch plans for a program of strategic research that broadened the focus of asphalt researchto include mixture design methods. In 1987, the U.S. Congress funded the Strategic HighwayResearch Program (SHRP).

In 1993, SHRP was completed with the delivery of 130 research products for implementationamong transportation agencies and other segments of the highway industry. The agents ofimplementation, including innovative partnerships and funding arrangements, teams, train-ing, and research centers, were deployed at various times throughout the process. The timelinein Figure 1 captures the sequence of some major events, but of course, cannot evoke the con-tributions of those whose commitment brought them about.

This report summarizes the work of the TRB Superpave Committee, which was formed in1999 to advise AASHTO and the Federal Highway Administration on a research plan thatwould further the development and deployment of the Superpave system. The committee’swork, however, is part of a larger canvas. Implementation efforts that began well before thecommittee was formed and still continue are the context for its work. For that reason, thisreport also briefly sketches the story of the campaign to bring the SHRP asphalt research prod-ucts, organized as the Superpave system, into general use. Because this retelling of the story is

PREFACE

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necessarily brief, it will only offer highlights from the deployment cam-paign. This is doubly hazardous. Aspects of the campaign critical to itssuccess will go unmentioned and the contributions of many organiza-tions and hard-working individuals will go unacknowledged.Furthermore, lessons to be learned from the innovative techniques usedin this campaign may go untaught and the innovations themselves lost tofuture technology deployment efforts. For these reasons, the members ofthe TRB Superpave Committee have recommended that the full “histo-ry” of Superpave development and deployment be captured for futurestudy. (The recommendation is made in the Committee’s 11th letter reportto the Federal Highway Administration and the American Association ofState Highway and Transportation Officials, which is on the Web athttp://www4.trb.org/trb/dive.nsf/web/superpave_final_letter_reports)

Joseph A. MickesChairman,

TRB Superpave Committee

1991AASHTO Task Force on Implementation formed

Round-Robin testing began

1992Superpave pooled fund test

equipment purchase

1993FHWA Superpave prototype

equipment delivered

AUPG & TWIGs formed Training contract w/ AI begunAASHTO created category of

provisional standards

1994First Superpave conference (Reno)

1995Superpave Centers established

19961st Superpave projects constructed by DOTs

Lead States Team activated

1997FHWA Technology Delivery Team formed

1998TEA-21 eliminates funding

Superpave Conference (St. Louis)

1999AASHTO assumes funding

TRB creates Superpave Committee ETGs organized

2000Long-range research plan developed

Superpave 2000 conference (Indianapolis)

2001World of Asphalt conference (Orlando)

14 research projects started

2002Lead States Team sunsets

2003World of Asphalt conference (Nashville)

2005Superpave binder standard adopted

by 52 DOTs

Mix design adopted by 36 DOTs Superpave Committee sunsets

FIG

URE

1: S

UPE

RPAV

E IM

PLEM

ENTA

TIO

N T

IMEL

INE

Long-lasting pavement that requires less maintenance, provides a smooth ride, and is agood value for taxpayers were the goals for asphalt research conducted during the

Strategic Highway Research Program (SHRP), which ended in 1993. At that time, focus andfunding shifted to the task of applying what was learned and implementing the test methods,engineering practices, and standard specifications that together comprise the Superpave sys-tem for selecting materials and designing pavement mixtures to meet specific climate and traf-fic conditions.

Although a prototype system was ready for deployment, its further refinement would requireactive guidance by experienced hands. This report briefly recounts the actions and outcomesthat were the contributions of the Transportation Research Board Superpave Committee to anationwide implementation effort. A brief sketch of that broader effort is included in chapter3 to provide context for the committee’s work.

Six years after the first full-scale production projects designed in accord with the Superpavesystem were placed in 1996, the asphalt industry awarded its highest honor to projects builtwith Superpave. That has remained the case for three consecutive years, illustrating that thesystem has become a mainstreamed technology. A survey conducted by the TRB SuperpaveCommittee to determine current use of Superpave found that 50 of 52 responding transporta-tion agencies report general use of the Superpave asphalt binder standard specification; theother two agencies are initiating plans to do so. Of the 52 responding agencies, 36 report gen-eral application of the Superpave mixture design standard, with 12 others reporting use onhigh-volume highways. Three other agencies have plans to initiate use. Results of the survey arediscussed in chapter 1.

The work of the TRB Superpave Committee was organized by what became known as the 2005Plan. Designed to meet four specific goals related to integrating Superpave into asphalt pave-ment engineering practice, the plan matched the four goals with four types of activity relatedto research, standards development, and technology transfer. Between 1999 and 2005, 25research projects related to developing and integrating Superpave were carried out throughTRB’s National Cooperative Highway Research Program (NCHRP). Chapter 2 relates the goalsof the 2005 Plan to the current status of efforts to meet them.

EXECUTIVE SUMMARY

Although it is apparent that implementation efforts have succeeded and that Superpave has infact been mainstreamed, members of the TRB Superpave Committee share concerns in sever-al areas of application. Chapter 4 discusses the committee’s recommendations regardingopportunities to improve, extend, or enhance the Superpave system and the performance ofhot-mix asphalt. In particular, the committee affirms that maximizing the value of the invest-ment in Superpave will require:

• studying the interactions that result in moisture damage to asphalt,

• developing calibrated, mechanistic HMA performance models,

• continuing research on mechanistic HMA performance models,

• meeting the mixture design needs of local transportation agencies,

• working with the construction industry to achieve well-built pavements, and

• ensuring that the useful lessons from this technology deployment program are available to others.

2

The first Superpave pavement was constructed on July8, 1992, when the Mathy Construction Company ofOnalaska, Wisconsin, and the Wisconsin Departmentof Transportation placed the first 500 feet of hot mixasphalt conforming to the then-prototypicalSuperpave asphalt binder and mixture specifications(Focus, 9/92). This 3-inch thick overlay was part of apilot study for a larger pavement performance experi-ment designed to validate the Superpave system. Thefirst 95 full-scale production projects designed inaccord with the Superpave system were placed in 1996.

Six years later, and for three consecutive years, the win-ner of the asphalt pavement industry’s prestigiousSheldon G. Hayes award, as well as both finalists in2004, used Superpave mixes to build their winningprojects. When asked if any conclusions aboutSuperpave could be drawn from these awards, DavidNewcomb, P.E., Ph.D., Vice President for Research andTechnology at the National Asphalt PavementAssociation (NAPA), offered that it illustrates howmainstreamed Superpave has become and shows thatSuperpave is a constructible mix that lends itself toquality pavement.

To determine the extent to which Superpave hasentered the mainstream, the TRB SuperpaveCommittee, with the assistance of the CanadianStrategic Highway Research Program, in March of2005, conducted a survey of the current use ofSuperpave asphalt binder and mixture standardsamong American state and Canadian provincialdepartments of transportation (DOTs). This survey

was a follow-on to similar surveys initially conductedby the American Association of State Highway andTransportation Officials (AASHTO) Lead States Team.The last of these was conducted in 2000 by the NewYork State DOT and the Federal HighwayAdministration (FHWA) at the behest of theSuperpave Committee (Mack 2001).

ASPHALT BINDER STANDARDS

Responses to the 2005 survey from the DOTs of the 50states, the District of Columbia, and Puerto Rico, indi-cate that the application of the Superpave asphaltbinder standard specification (AASHTO M 320) isalmost universal and will be so by the end of 2006.Currently, 50 of these 52 agencies reported generalusage. The two agencies not yet using the Superpavebinder standards, the Alaska DOT and Caltrans,reported they are initiating plans for general use.Alaska uses the Superpave binder standards on someprojects now and California will deploy the binderstandards in 2006. Seven of the 10 provincial DOTsalso reported general use of Superpave binder stan-dards.

Several other agencies also responded to the survey.The Central Federal Lands Division and the WesternFederal Lands Division of the FHWA reported generaluse of the binder standards on projects under theirjurisdiction, as did the Pennsylvania Turnpike. TheFederal Aviation Administration indicated that thebinder standards were used on some runway projects.

3

CURRENT STATUS OF SUPERPAVE IMPLEMENTATION

1

ASPHALT-AGGREGATE MIXTURE DESIGNSTANDARDS

Although the use of Superpave mixture design stan-dards is predominant among state DOTs, general usageis not universal. Thirty-six of the 52 American DOTsreported general application. Another 12 reported useon some projects, primarily on higher volume road-ways. Four agencies do not use the mixture standardsat all, although three of the four have formulated plansto do so. The fourth is initiating research regarding theadoption of the Superpave mixture test methods.

In Canada, only three provincial DOTs reported gener-al use of the Superpave standards for mixture design.Only one other provincial DOT reported a plan toadopt the Superpave standards in the future. Amongthe other American agencies reporting, all four use themix standards on some projects, at least. Figure 2 sum-marizes the survey responses.

USE BY COUNTY AND MUNICIPAL ROADSAGENCIES

The seventh letter report of the committee (November29, 2001) stated:

Among state DOTs, Superpave is rapidly supplantingother systems of hot mix asphalt materials selection andmixture design. Among local agencies, however,

Superpave deployment is lagging. This situation is notuncommon. New highway technologies are often intro-duced at the state level and then disseminated amonglocal agencies at a much slower pace. In the case ofSuperpave, however, this situation may lead to unintend-ed consequences for many local agencies. If the rate ofdeployment among state departments of transportation(DOTs) continues to outpace deployment among localagencies, the hot mix asphalt paving industry will eitherhave to support dual systems or the Superpave systemwill be practically imposed on local roads agencies.

(All letter reports are available on the TRB Web site athttp://www4.trb.org/trb/dive.nsf/web/superpave_final_letter_reports)

The 2005 survey indicates that the application ofSuperpave among local agencies continues to lag. Thesurvey was not directly sent to local roads agencies;rather each state and provincial agency was queriedabout the use of Superpave by local agencies within itsjurisdiction. While this approach necessarily intro-duces some uncertainty to the results, the state andprovincial agencies work closely with their municipalcounterparts in planning road construction projects,so the degree of uncertainty is judged to be minor.

The 52 American DOTs reported that in 20 states, localagencies used the Superpave system in conformancewith state DOT standards. In two states, some localagencies used Superpave standards that did not con-form to the state DOT standards. In 33 states, therewas no general usage of Superpave by counties andmunicipalities. That there were 55 responses from 52states indicates that, in some states, some municipali-ties specified Superpave and others did not.

The situation in Canada is also uneven. In twoprovinces, local agencies specify Superpave materialsfollowing provincial specifications. In two provinces,other guide specifications are employed, and in sixprovinces, local agencies do not specify Superpave. C-SHRP also sent the questionnaire to four major cities,all of which specify the Superpave system on at leastsome projects. Three of those cities are in provincesthat do not currently specify Superpave.

There exists a general concern among the TRBSuperpave Committee members that in those stateswhere the DOT specifies Superpave binders and mix-tures, these same materials are being supplied to local

4 SUPERPAVE: PERFORMANCE BY DESIGN

FIGURE 2

agencies that are not fully aware of the nature of theproducts. In the Washington State DOT response tothe questionnaire, Tom Baker, the DOT materials engi-neer, captured the committee’s concern perfectly:“Local agencies do not know or test what they are get-ting.” In the Superpave system, binders and aggregatesare selected and mixtures are designed to meet specif-ic climatic and traffic conditions. If such mixes areunknowingly used in other situations, unanticipateddurability and performance problems may arise. Eventhe best materials, if used inappropriately, will performpoorly. Materials selected and mixed for heavy dutystate highways are likely to be too coarse, too stiff, andtoo low in asphalt content to perform well on residen-tial streets or farm-to-market roads. Such roads requireSuperpave mix suitable for lower volume, lighter dutyroadways.

ESTABLISHING BENEFITS AND COSTS

Adoption of the Superpave system is not inexpensive.New test equipment must be purchased, installed andmaintained, and staff must be trained in its use.Ultimately, however, the decision to adopt Superpave isdriven by the ratio of anticipated performance benefitsto construction costs. The denominator of this equa-tion is easily and quickly established. Cost is evident assoon as construction project bids are opened. Thenumerator, or benefit, is established only over a longperiod of time as performance gains reveal themselves.In the report Economic Benefits of SHRP Research,Little et al. (1997) at the Texas Transportation Institute(TTI) projected that under an adoption scenario thattook 10 years for full implementation, the Superpavebinder specifications would yield $482 million in dis-counted savings to state DOTs in the tenth year alone.

The TTI analysis, based on a handful of necessarilyshort-term case histories, was highly speculative.Obviously, the authors had to make many assumptionsabout the extra costs associated with asphalt bindersspecified with the Superpave system and whether theperformance changes indicated by the short-termstudies would actually be realized. The TTI study pre-sumed that Superpave PG binder would be 6-7% moreexpensive than other binders being supplied in 1996.This was based on increases seen in the case studies. Inthe 2000 study of Superpave needs and assessment,New York State DOT reported a price differential of

2.5% (Mack and Dunn, 2001) The 2005 survey couldnot address the issue of cost, simply because the pre-vailing use of the Superpave binder specifications nowmasks any cost differential. In the few instances whererespondents did mention price differential, it was onlyto remark that none existed or were minor.

The 2005 questionnaire did address performance,however. Each DOT was asked: “Has your agencyidentified performance changes associated withSuperpave from your pavement management system,program planning or similar documentary source?”Twenty-two of the 72 respondents replied affirmative-ly. In some instances, agencies indicated that they aremonitoring performance but no significant differenceshave yet been noted. Others report significantimprovements. Reduced rutting is the most common-ly cited performance benefit. Thirteen agenciesreported that they had conducted studies into thecause of observed performance changes. Ten agenciesindicated they had performed benefit/cost studies, butonly seven of these are apparently based on locallyobtained performance data. Table 1 lists commentsoffered in response to this question both in the surveyand in direct conversation with some state officials.

While it may be disappointing that so few agencieshave gathered performance data, nonetheless, there isevidently sufficient data on hand to warrant anotherexamination of the benefits and costs attributable tothe Superpave system. A complete tabulation of surveyresponses is provided in Table 2.

UNIFORMITY IN IMPLEMENTATION

From the initiation of the Superpave deployment cam-paign, FHWA, AASHTO, and the TRB SHRP and TRBSuperpave Committees have been consistent in urgingthat the Superpave system be implemented in a uni-form fashion. This was not just an appeal to the engi-neering community’s sense of order. There were bothtechnical and economic reasons for this early emphasison standardization. When first developed, the trueprecision of the various Superpave test methods wasnot firmly established and inter-laboratory testingusing procedures in common was needed to completethis task. A considerable training effort had to beundertaken and this task would only be made moredifficult if each jurisdiction adopted even slightly dif-ferent standards. Equipment manufacturers had to

5CURRENT STATUS OF SUPERPAVE IMPLEMENTATION

know that their products would be acceptable acrossjurisdictions. Most importantly, from an economicstandpoint, materials suppliers had to know that theywould not have to make separate production adjust-ments to satisfy a wide array of specifications from dif-ferent jurisdictions.

Conversely, no engineering system can be permanent-ly static. All such systems are, or should be, subject tocontinuous improvements. As users of any systemgain experience, they will note weaknesses that can be

strengthened and deficiencies that should beaddressed. In a newly instituted system, early use gen-erally identifies many potential improvements. If thatearly experience is relatively uniform, guidance can bedeveloped on precisely how to modify the system. Thishas certainly been true with Superpave. There hasbeen noticeable evolution from the provisional specifi-cations and test methods originally adopted by AASH-TO. The progression of standards and test methodsfrom provisional to full standard has been the majorwork of the Mix and Binder Expert Task Groups.Working with input from the states and industry, theETGs reshaped uncertain and unreliable provisionaltests and methods into well-vetted specifications thatdependably produce the expected outcome. Since1995, research findings have resulted in 21 full stan-dard specifications, six currently provisional stan-dards, and eight future standards that are now beingdeveloped.

In the 2005 survey, the TRB Superpave Committeesought to establish just how uniformly, in generalterms, Superpave was being applied among the stateDOTs. Among the 50 state agencies that responded tothe question, 35 indicated general conformance toAASHTO standards and 15 reported that agency stan-dards were modified from AASHTO standards. Whilethis may be the historically highest level of standardi-zation for hot mix asphalt specifications among stateDOTs, it is still far from uniform.

The 2005 survey sought to establish the general statusof application of the Superpave system and not toidentify variations among DOTs. Some informationabout these variations is available from other sources,however.

In February 2005, Ken Grzybowski of PRI AsphaltTechnologies, Inc., reported to the Association ofModified Asphalt Producers on the results of a surveyhe conducted on Superpave “plus” asphalt binder spec-ifications in use by the state DOTs. (Grzybowski 2005).As the name implies, a “plus” specification is one inwhich the AASHTO standard specification M 320 hasbeen supplemented with additional requirements.According to this survey, 34 state DOTs use the AASH-TO standards with additional requirements. The“plus” requirements include specification testsretained from pre-Superpave specifications, prescrip-tions that limit asphalt modification options either by

6 SUPERPAVE: PERFORMANCE BY DESIGN

Arkansas Problems that were common withMarshall mixes occurred considerablyless often

Connecticut Noticed reduced rutting on pavementsegments prone to rutting

Louisiana Less rutting observed

Minnesota Better ride & pavement sufficiency,slightly lower cost

New York City No cost increase, 1-3 years in extra per-formance

Ontario 2% lower in cost, 1-2 years increasedperformance

Pennsylvania Seems to have resolved the rutting prob-lem

Test Section SPS-9 Reflective cracking retarded 3-4 years

Utah 3-year life increase, 10% LCC savings

Utah DOT Region 2 Crack sealing cost down 70%, patchingcosts down 20%

Washington State 3% higher in cost, 12-20% longer per-formance

City of Calgary Better performance at same cost

City of Ottawa Marked reduction in cracking

TABLE 1: Benefit Indicators

specifying or excluding the use of certain materials ortechniques, or added tests for properties not consid-ered in the AASHTO standards. The use of “plus” hasincreased since 2002 when Tandon and Avelar report-ed that 16 of 47 DOTs used such modified standards.

SUMMARY

In sum, almost all state DOTs are currently using theSuperpave system. If the plans of the few state DOTs

that do not use Superpave are carried out, deploymentof Superpave will be universal. Universality, however,is not synonymous with uniformity. A significantnumber of state DOTs do not apply the mixture designprocedures on all projects. The number of DOTs thatuse additional specifications along with the AASHTOSuperpave binder standard is large and has grownrecently. Nor does the near—universal applicationamong state DOTs extend to county and municipaltransportation agencies, where knowledge of theappropriate use of the system is still limited.

7CURRENT STATUS OF SUPERPAVE IMPLEMENTATION

8

AASHTO Subcommittee on Materials -- Questionnaire on Use of Superpave Standards — Final Summary — April 6, 2005

TABLE 2: 2005 SUPERPAVE SURVEY RESULTS

Use Binder Use Mix Plans to Use Plans to General Conformance Standards Now? Standards Now? Binder? Use Mix? with AASHTO Standards

Agency Yes, On Some No Yes, On Some No Yes No Yes No AASHTO Modified OtherGenerally Projects Generally Projects ASSHTO

Sum of DOT 50 1 1 36 12 4 2 0 5 0 35 15 0Responses

Alabama X X X

Alaska* X* X* X* X*

Arizona* X X X

Arkansas* X X X

California* X* X* X* X*

Colorado X X X

Connecticut* X X X

Delaware* X X X

DC X X X

Florida X X X

Georgia* X X* X

Hawaii X X X

Idaho X X X X

Illinois* X X X

Indiana X X X

Iowa* X X X

Kansas X X X

Kentucky X X X

Louisiana* X X X

Maine* X X X*

Maryland X X X

Massachusetts X X X

Michigan* X X X

Minnesota X X X

Mississippi X X X

Missouri X X X

Montana X X X X

Nebraska X X X

Nevada* X X X*

9

Performance Changes Cause of Changes Cost/Benefit Used by Counties ContactDocumented? Investigated? Analysis? and Municipalities?

Yes No Yes No Yes No State Other No E-mail address of respondentSpec’s Spec’s

13 39 8 10 4 48 20 2 33

X X X X X X mountcastler@dot.state.al.us

X X X scott_gartin@dot.state.ak.us

X X X* jnodes@azdot.gov

X* X X X jerry.westerman@arkansashighways.com

X X X phil.stolarski@dot.ca.gov

X X X tim.aschenbrener@dot.state.co.us

X* X X keith.lane@po.state.ct.us

X X X* X james.pappas@state.de.us

X X wasi.khan@dc.gov.

X X X X X* jim.musselman@dot.state.fl.us

X X X georgene.geary@dot.state.ga.us

X X X joanne.nakamura@hawaii.gov.

X X X mike.santi@itd.idaho.gov

X* X X X trepanierjs@dot.il.gov

X X X X dandrewski@indot.state.in.us

X* X X X michael.heitzman@dot.state.ia.us

X X X lingram@ksdot.org

X X X X allen.myers@ky.gov

X* X X X* X* scooper@dotd.louisiana.gov

X X X bruce.yeaton@maine.gov

X X X X lmichael@sha.state.md.us

X X X clement.fung@mhd.state.ma.us

X* X* X bleechc@michigan.gov

X X X john.garrity@dot.state.mn.us

X X X X sheffield@mdot.state.ms.us

X X X jason.ewalt@modot.mo.gov

X X X X sbarnes@state,mt.us

X X X X lweishah@dor.state.ne.us

X X X dweitzel@dot.state.nv.us

10

Agency Yes, On Some No Yes, On Some No Yes No Yes No AASHTO Modified OtherGenerally Projects Generally Projects ASSHTO

Use Binder Use Mix Plans to Use Plans to General Conformance Standards Now? Standards Now? Binder? Use Mix? with AASHTO Standards

AASHTO Subcommittee on Materials -- Questionnaire on Use of Superpave Standards — Final Summary — April 6, 2005

TABLE 2: 2005 SUPERPAVE SURVEY RESULTS

New Jersey X X X

New Hampshire* X X X

New Mexico X X X

New York X X X

North Carolina X X X

North Dakota X X X

Ohio X X X

Oklahoma* X* X X

Oregon X X X

Pennsylvania* X X X

Puerto Rico X X X

Rhode Island X X X

South Carolina X X X

South Dakota X X X

Tennessee* X X X* X

Texas X X X

Utah* X X X

Vermont X X X

Virginia X X X

Washington X X X

West Virginia* X* X X

Wisconsin X X X

Wyoming X X X

Sum of US Other 3 1 0 2 2 0 1 0 1 0 2 2 0responses _

Cent. Fed. Lands X X X

West. Fed. Lands X X X

Penna. Turnpike X X X

Fed Aviation X X X X XAdmin.

11

Yes No Yes No Yes No State Other No E-mail address of respondentSpec’s Spec’s

Performance Changes Cause of Changes Cost/Benefit Used by Counties ContactDocumented? Investigated? Analysis? and Municipalities?

X X X* eileen.sheehy@dot.state.nj.us

X* X* X X arawson@dot.state.nh.us

X X X john.tenison@nmshtd.state.nm.us

X X X rthielke@dot.state.ny.us

X X X cljones@dot.state.nc.us

X X X rhorner@state.nd.us

X X X david.powers@dot.state.oh.us

X X X dgierhart@odot.org

X X X bruce.m.patterson@odot.state.or.us

X* X X* rapple@state.pa.us

X X X aalvarez@act.dtop.gov.pr

X X X mpbyrne@dot.state.ri.us

X X X hawkinscw@scdot.org

X X X rick.rowen@state.sd.us

X X X brian.egan@state.tn.us

X X X X rizzo@dot.state.tx.us

X* X X* tbiel@utah.gov

X X X ted.domey@state.vt.us

X X X X bill.bailey@vdot.virginia.gov

X X X X* bakert@wsdot.wa.gov

X X X lbarker@dot.state.wv.us

X X X X judith.ryan@dot.state.wi.us

X X X rick.harvey@dot.state.wy.us

1 3 0 1 0 4 0 0 0

X X michael.peabody@fhwa.dot.gov

X X brad.nietzke@fhwa.dot.gov

X X X mwagner@paturnpike.com

X X jeffrey.rapol@faa.gov

12

Agency Yes, On Some No Yes, On Some No Yes No Yes No AASHTO Modified OtherGenerally Projects Generally Projects ASSHTO

Use Binder Use Mix Plans to Use Plans to General Conformance Standards Now? Standards Now? Binder? Use Mix? with AASHTO Standards

AASHTO Subcommittee on Materials -- Questionnaire on Use of Superpave Standards — Final Summary — April 6, 2005

TABLE 2: 2005 SUPERPAVE SURVEY RESULTS

Sum of 9 3 3 4 4 7 0 3 1 4 11 2 0Canadian Responses_

Alberta* X* X X* X

Calgary, Alb.* X X X

Edmonton, Alb. X X X

British Columbia X X X X X

Vancouver, BC* X* X X

Manitoba X X X X

New Brunswick X X X

Newfoundland X X X X

Northern Terr's X X

Nova Scotia X X X X

Ontario X X X

Ottawa,Ont.* X X X

Pr.Edward Is.* X X* X

Quebec* X X* X

Saskatchewan* X X* X X

13

Yes No Yes No Yes No State Other No E-mail address of respondentSpec’s Spec’s

Performance Changes Cause of Changes Cost/Benefit Used by Counties ContactDocumented? Investigated? Analysis? and Municipalities?

8 5 5 3 6 8 2 2 7

X* X* X X* chuck.mcmillan@gov.ab.ca

X* X X* ken.yeung@calgary.ca

X X X hugh.donovan@edmonton.ca

X X X X mike.oliver@gov.bc.ca

X X X

X X X X

X X X terry.hughes@gnb.ca

X X X brennand@gov.nl.ca

X larry_purcka@gov.nt.ca

X X X gouthrto@gov.ns.ca

X X X kai.tam@mto.gov.on.ca

X* X X* steve.goodman@ottawa.ca

X X X jtkelly@gov.pe.ca

X X X X* miparadis@mtq.gouv.qc.ca

X* X mbeshara@highways.gov.sk.ca

The program of research and development to accom-plish the general deployment of the Superpave systembegan in 1993 and continues to this day. The effort canbe divided into two distinct time periods. The firstperiod was largely coincident with the span of theIntermodal Surface Transportation Efficiency Act(ISTEA) of 1991. This act provided substantial fund-ing to encourage the implementation of the researchresults of the Strategic Highway Research Program(SHRP) including the Superpave system. For the mostpart, research and technology transfer during this peri-od was guided by the Federal Highway Administration(FHWA). Associated standards development was guid-ed by AASHTO, and TRB maintained the TRB SHRPcommittee of stakeholders and experts to adviseFHWA and AASHTO on the overall SHRP implemen-tation campaign.

The second phase has coincided with the TransportationEquity Act for the 21st Century (TEA-21) enacted in1998. This legislation did not continue funding to sup-port the deployment of Superpave and threatened toleave the effort half completed. In response, the statedepartments of transportation, acting through AASH-TO, agreed to continue the R&D aspects of the deploy-ment effort via the National Cooperative HighwayResearch Program (NCHRP). AASHTO and the FHWAasked TRB to organize the TRB Superpave Committee toadvise on the content of this R&D effort, monitorprogress, and coordinate the activities of the variousresearch and technology transfer agencies. The TRBSuperpave Committee was organized in early 1999.

Any discussion of Superpave deployment and its asso-ciated R&D activities must begin with the understand-ing that hot mix asphalt paving is an engineering sys-tem with many interrelated components. Any changeto one or more components of this system requiresadjustment among the remaining components. If thechanges are large and revolutionary, as is the case withSuperpave, many adjustments within this HMA engi-neering system, either to Superpave or to other com-ponents, must be accommodated within a very shorttime. Much of the R&D that occured during thedeployment phase was occasioned by the need for sys-tem accommodation.

Immediately upon its organization, the SuperpaveCommittee began work on a strategic plan to guideSuperpave deployment activities. After compiling theplan, the committee judged that deployment ofSuperpave would be largely complete by late 2005 andthe plan became known as the “2005 Long Range Plan”or simply the “2005 Plan.” This plan was designed tomeet four goals.

1. The Superpave system will recommend asphaltbinder type and mixture proportions based onenvironmental conditions, anticipated traffic loadsand layer location.

2. The Superpave System will predict the ability ofa mix to withstand rutting, fatigue, thermal crack-ing and moisture damage through a series of labo-ratory tests.

15

MEETING THE R&D GOALS OF SUPERPAVEDEVELOPMENT AND DEPLOYMENT

2

3. The Superpave system will integrate the binderand mix requirements into performance-basedspecifications for HMA pavement construction.

4. Superpave will be fully comprehended by theSDOTs and the HMA industry.

These four goals succinctly codified the objectives ofthe original SHRP asphalt research, the nature of theadjustments needed to integrate Superpave into HMAengineering practice, the accommodation ofSuperpave to other evolving HMA research, and thenecessary reliance on technology transfer to completethe program. To meet these goals, the 2005 Plan rec-ommended substantial efforts involving four types ofactivities:

1. Research and development to integrateSuperpave into the HMA engineering system.

2. New research to address essential questions notcompletely answered by the SHRP asphalt researchprogram.

3. Continuation of the aggressive program ofengineering standards development initiated byAASHTO.

4. A multi-faceted program of technology transfer,training, and facilitation to inform and enable theproper application of Superpave by agency andindustry personnel or alert them how the intro-duction of Superpave will impact related activitiessuch as construction.

Matching the four goals and the four types of activitiesthat comprise the 2005 Plan can be confusing becausethere is not a one-to-one correspondence between aparticular goal and a specific activity. Even specificprojects might address more than one goal. Table 3tabulates the R&D projects related to Superpavedeployment. The table illustrates how many projectsaddress more than one goal. Indeed, NCHRP Project9-33, currently in progress, is addressing all four goals.The following discussion of Superpave DeploymentR&D is organized by activity type and correlation togoals is related in the text. Because of the overarchingnature of the technology transfer efforts, these activi-ties are discussed separately in chapter 3.

ACTIVITY TYPE 1: INTEGRATION R&D

Of the 25 Superpave-related NCHRP projects under-taken in accord with the 2005 plan, 14 directly enabled

the integration of Superpave into overall HMA pavingpractice. While discussion of all 14 would be toolengthy to include here, several examples will illustratethe nature of these projects and why their completionwas essential to the deployment program.

Superpave and Recycled Asphalt Pavement

The SHRP research did not consider the inclusion ofrecycled asphalt pavement (RAP) in Superpave mix-tures. The growth of pavement recycling in recentyears showed this to be a major gap. The Superpavesystem did not quantify how, or even if, the inclusionof RAP with aged asphalt would affect the propertiesof Superpave performance-graded binders. It was noteven certain if RAP functioned as “black rock” with lit-tle or no mixing of the older and new asphalt bindersor if the aged binder was mixed with the new asphaltbinder in the mixing and paving process. NCHRPProject 9-12 was undertaken to answer these questionsand to provide more definitive guidelines on the use ofRAP in Superpave mixes.

The final product of NCHRP project 9–12 consists ofa technical report supported by seven appendices,which was published as:

• NCHRP CD-ROM CRP-CD-44, “RecommendedUse of Reclaimed Asphalt Pavement in theSuperpave Mix Design Method,” contains a 12-minute video presentation on the incorporation ofRAP into hot mix asphalt designed with theSuperpave method.

• The appendix titled “Summary: Guidelines forIncorporating Reclaimed Asphalt Pavement in theSuperpave System” has been published as ResearchResults Digest 253.

• The appendix titled “Use of RAP in Superpave:Technicians’ Manual” has been published asNCHRP Report 452 .

• The main report and the remaining appendiceshave been published as NCHRP Web Document 30.

NCHRP Report 452 provides comprehensive guide-lines on the sampling, testing, mixture handling, andmixing of RAP with new binders and aggregates toensure a reliable HMA is produced. Without thisresearch, although it does not directly address theSuperpave system, the general deployment ofSuperpave would have been significantly delayed.

This research addressed goals 1, 3 and 4.

16 SUPERPAVE: PERFORMANCE BY DESIGN

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nge.

2,3

2,3 3 2 2 1 2,3 2

2002

2003

1993

1996

2000

1996

1997

1998

Com

plet

e

2005

Com

plet

e

Com

plet

e

2005

Com

plet

e

Com

plet

e

Com

plet

e

Non

e av

aila

ble

NCH

RP R

epor

t 409

NCH

RP R

RD 2

37

NCH

RP R

epor

t 459

NCH

RP R

epor

t 452

NCH

RP R

epor

t 464

Title

Obj

ectiv

e (if

act

ive)

or P

rodu

ctG

oals

Sup

erpa

ve 2

005

Plan

St

art

Due

Repo

rt o

f Ref

eren

ce

Title

Obj

ectiv

e (if

act

ive)

or P

rodu

ctG

oals

St

art

Due

Repo

rt o

f Ref

eren

ceSu

perp

ave

2005

Pla

n

GO

ALS

1. R

ecom

men

d bi

nder

type

and

mix

ture

pro

port

ions

bas

ed o

n en

viro

nmen

t, lo

ad, a

nd la

yer l

ocat

ion.

2. P

redi

ct th

e ab

ility

of a

mix

to w

ithst

and

rutti

ng, f

atig

ue, t

herm

al c

rack

ing,

and

moi

stur

e da

mag

e th

roug

h a

seri

es o

f lab

orat

ory

test

s.

2/3.

Inte

grat

e pr

oduc

ts d

eriv

ed fr

om th

e M

echa

nist

ic-E

mpi

rica

l Pav

emen

t Des

ign

Gui

de in

to th

e 20

05 m

ix d

esig

n m

etho

d an

d th

e H

MA

per

form

ance

rela

ted

spec

ifica

tion

(PRS

).

3. In

tegr

ate

the

bind

er a

nd m

ix re

quir

emen

ts in

to P

RS fo

r HM

A c

onst

ruct

ion.

4. B

e fu

lly c

ompr

ehen

ded

by th

e st

ates

and

indu

stry

thro

ugh

initi

al a

nd c

ontin

uing

edu

catio

nal p

rogr

ams.

17

TAB

LE 3

R&D

PRO

JECT

S RE

LATE

D T

O S

UPE

RPAV

E D

EPLO

YMEN

T

18

NCH

RP 9

-16,

Rel

atio

nshi

pBe

twee

n Su

perp

ave

Gyra

tory

Com

pact

ion

Prop

ertie

s an

dPe

rman

ent D

efor

mat

ion

ofPa

vem

ent i

n Se

rvic

e

NCH

RP 9

-19,

Sup

erpa

ve S

uppo

rtan

d Pe

rform

ance

Mod

els

Man

agem

ent

NCH

RP 9

-20,

Per

form

ance

-Rel

ated

Spec

ifica

tions

for H

ot-M

ix A

spha

ltCo

nstru

ctio

n

NCH

RP 9

-22,

PRS

– B

eta

Test

ing

and

Valid

atio

n of

HM

A (A

ctiv

e)

NCH

RP 9

-23,

Inte

grat

ed C

limat

icM

odel

(ICM

) Val

idat

e w

ith L

TPP

Seas

onal

Mon

itorin

g Pr

ogra

m(A

ctiv

e)

NCH

RP 9

-25,

Req

uire

men

ts fo

rVo

ids

in M

iner

al A

ggre

gate

for

Supe

rpav

e M

ixes

(Act

ive)

NCH

RP 9

-27,

HM

A in

-pla

ce A

irVo

ids,

Lift

Thi

ckne

ss a

ndPe

rmea

bilit

y

NCH

RP 9

-29

Sim

ple

Perfo

rman

ceTe

ster

(SPT

) for

Sup

erpa

ve M

ixDe

sign

NCH

RP 9

-30,

Exp

erim

enta

l Pla

n fo

rCa

libra

tion

and

Valid

atio

n of

HM

APe

rform

ance

Mod

els

for M

ix a

ndSt

ruct

ural

Des

ign

Resu

lts s

ugge

sted

that

N-S

Rmax

pro

vide

s a

rapi

d m

eans

of i

dent

i-fy

ing

gros

s HM

A m

ix in

stab

ility

or r

uttin

g po

tent

ial d

urin

g vo

lum

et-

ric m

ix d

esig

n. b

ut it

is n

ot a

fund

amen

tal m

ater

ial p

rope

rty fo

rpr

edic

ting

the

deve

lopm

ent o

f per

man

ent d

efor

mat

ion.

The

dyna

mic

mod

ulus

test

reco

mm

ende

d as

the

prim

ary

sim

ple

perfo

rman

ce te

st fo

r rut

ting.

The

flow

num

ber (

repe

ated

load

per

-m

anen

t def

orm

atio

n) te

st p

rovi

des

an o

ptio

nal,

com

plem

enta

rypr

oced

ure

for e

valu

atin

g th

e re

sist

ance

of a

n HM

A m

ix d

esig

n to

terti

ary

flow

.

Deve

lop

a pe

rform

ance

rela

ted

spec

ifica

tion

for H

MA

cons

truc-

tion

Eval

uate

and

def

ine

HMA

PRS,

inco

rpor

ate

2002

mod

els

Valid

ate

Inte

grat

ed C

limat

ic M

odel

(ICM

) dev

elop

ed in

NCH

RPPr

ojec

t 1-3

7A w

ith L

TPP

data

; (2)

dev

elop

pra

ctic

al g

uide

lines

for

sele

ctin

g IC

M in

put d

ata

sets

; (3)

ver

ify th

e es

timat

ed p

erio

d or

rate

of a

ging

sim

ulat

ed b

y th

e cu

rren

t Sup

erpa

ve b

inde

r and

hot

mix

asp

halt

cond

ition

ing

proc

edur

es --

AAS

HTO

prov

isio

nal p

rac-

tices

PP1

and

PP2

– w

ith L

TPP

data

; and

(4) r

evis

e th

e cu

rren

tco

nditi

onin

g pr

oced

ures

as

nece

ssar

y fo

r use

in S

uper

pave

sys

-te

m.

The

obje

ctiv

e of

this

rese

arch

is to

dev

elop

reco

mm

ende

d m

ixde

sign

crit

eria

for V

MA,

VFA

, or c

alcu

late

d bi

nder

film

thic

knes

s,as

app

ropr

iate

, to

ensu

re a

dequ

ate

HMA

dura

bilit

y an

d re

sist

ance

to p

erm

anen

t def

orm

atio

n an

d fa

tigue

cra

ckin

g in

the

cont

ext o

fth

e Su

perp

ave

mix

des

ign

met

hod.

Guid

elin

es o

n co

mpa

ctio

n an

d co

ntro

lling

per

mea

bilit

y HM

A.

Desi

gned

, pro

cure

d, a

nd e

valu

ated

sim

ple

perfo

rman

ce te

ster

s fo

rus

e in

Sup

erpa

ve m

ix d

esig

n an

d in

HM

A m

ater

ials

cha

ract

eriza

-tio

n fo

r pav

emen

t stru

ctur

al d

esig

n. W

ider

pro

cure

men

t pla

nned

.

Deve

lope

d a

prac

tical

exp

erim

enta

l pla

n to

refin

e th

e ca

libra

tion

and

valid

atio

n of

the

perfo

rman

ce m

odel

s of

the

NCH

RP 1

-37a

desi

gn g

uide

with

labo

rato

ry-m

easu

red

hot m

ix a

spha

lt (H

MA)

mat

eria

l pro

perti

es fo

r use

in fu

ture

mix

and

stru

ctur

al d

esig

nm

etho

ds.

2 2 3 3 2 3 3,4

2,3 2

1999

1999

1998

2000

2001

2001

2001

2001

2001

Com

plet

e

Com

plet

e

Com

plet

e

2007

2005

2005

2003

2006

2004

NCH

RP R

epor

t 478

NCH

RP R

epor

t 465

NCH

RP R

epor

t 455

NCH

RP R

epor

t 531

NCH

RP R

epor

t 513

&N

CHRP

Rep

ort 5

30

NCH

RP R

RD 2

83

Title

Obj

ectiv

e (if

act

ive)

or P

rodu

ctG

oals

Sup

erpa

ve 2

005

Plan

St

art

Due

Repo

rt o

f Ref

eren

ce

Title

Obj

ectiv

e (if

act

ive)

or P

rodu

ctG

oals

St

art

Due

Repo

rt o

f Ref

eren

ceSu

perp

ave

2005

Pla

n

Con

tinu

ed

NCH

RP 9

-31,

Air

Void

Requ

irem

ents

for S

uper

pave

Mix

Desi

gn (A

ctiv

e)

NCH

RP 9

-33,

A M

ix D

esig

n M

anua

lfo

r Hot

Mix

Asp

halt

(Act

ive)

NCH

RP 9

-34

Impr

oved

Cond

ition

ing

Proc

edur

e fo

rPr

edic

ting

the

Moi

stur

eSu

scep

tibili

ty o

f HM

A Pa

vem

ents

(Act

ive)

NCH

RP 9

-35

Aggr

egat

e Pr

oper

ties

and

Thei

r Rel

atio

nshi

p to

the

Perfo

rman

ce o

f Sup

erpa

ve-

Desi

gned

HM

A: A

Crit

ical

Rev

iew

FHW

A 90

-01,

Sup

erpa

ve M

ix -

Prot

ocol

Ref

inem

ent a

nd F

ield

Valid

atio

n

FHW

A 90

-02

Supe

rpav

e - B

inde

rEq

uipm

ent &

Tes

t Pro

cedu

res

–Re

finem

ent a

nd F

ield

Val

idat

ion

FHW

A 90

-03,

Sup

erpa

ve M

ixTe

nder

ness

FHW

A 90

-04,

Inve

stig

atio

n of

Mod

ified

Asp

halt

Syst

ems

FHW

A 90

-05,

Fin

e Ag

greg

ate

Spec

ific

Grav

ity T

est

FHW

A 90

-06

Rugg

edne

ss T

estin

gof

Sup

erpa

ve S

hear

Tes

ter a

ndIn

dire

ct T

ensi

le T

este

r

FHW

A 90

-07

& 0

9, U

nder

stan

ding

the

Perfo

rman

ce o

f Mix

ture

s w

ithM

odifi

ed A

spha

lt Bi

nder

s an

dAs

phal

t Mas

tics

TPF-

5 (0

19) A

LF P

oole

d Fu

nd S

tudy

SPR

2/21

1 Ev

alua

tion

of C

orel

okDe

vice

Reco

mm

end

air v

oid

cont

ents

requ

ired

for d

urab

ility

and

resi

st-

ance

to p

erm

anen

t def

orm

atio

n.

Deve

lop

a ne

w m

ix d

esig

n m

anua

l for

HM

A. C

apst

one

prod

uct o

fSu

perp

ave

depl

oym

ent.

Deve

lop

an im

prov

ed c

ondi

tioni

ng p

roce

dure

bas

ed o

n th

e en

vi-

ronm

enta

l con

ditio

ning

sys

tem

(ECS

) for

eva

luat

ing

the

moi

stur

esu

scep

tibili

ty o

f com

pact

ed H

MA

in c

ombi

natio

n w

ith th

e si

mpl

epe

rform

ance

test

(SPT

).

Revi

ew o

f the

tech

nica

l lite

ratu

re to

iden

tify

cons

ensu

s, s

ourc

e,an

d ot

her a

ggre

gate

pro

perti

es th

at s

igni

fican

tly im

pact

HM

A pe

r-fo

rman

ce.

Mob

ile la

bora

tory

that

val

idat

es N

CHRP

out

put,

incl

udin

g PR

S,gy

rato

ry a

dvan

cem

ents

, and

vol

umet

ric re

quire

men

ts

Labo

rato

ry v

alid

atio

n of

all

bind

er a

dvan

cem

ents

, inc

ludi

ng a

ging

,m

odifi

er te

sts,

and

dire

ct te

nsio

n te

sts.

Rese

arch

reas

ons

behi

nd m

ix te

nder

ness

issu

es

Rese

arch

to e

valu

ate

mod

ified

bin

der m

ix p

rope

rties

in th

e la

bora

-to

ry

Rese

arch

to e

valu

ate

new

fine

agg

rega

te s

peci

fic g

ravi

ty te

sts

Cond

uct r

ugge

dnes

s te

stin

g of

two

sepa

rate

SHR

P de

velo

ped

devi

ces

- the

Sup

erpa

ve S

hear

Tes

ter (

SST)

and

the

Indi

rect

Tens

ile T

este

r.

Rese

arch

that

will

lead

to fi

nal b

inde

r tab

le th

at c

lear

ly id

entif

ies

rela

tions

hip

of b

inde

r to

mix

ture

per

form

ance

.

Rese

arch

to v

alid

ate

labo

rato

ry te

sts

cond

ucte

d on

mod

ified

bind

er m

ixes

and

to v

alid

ate

2002

mod

els

pred

ictiv

e ca

pabi

litie

s.

3

1,2,

3,4

1,2

3,4

1,2,

4

1,4

2,3 1 2,3 2 1 1,2 2

2001

2004

2002

2002

2005

2005

2005

2004

2005

2004

Com

plet

e

2004

Com

plet

e

Com

plet

e

2004

2004

2002

NCH

RP R

epor

t 539

19

http

://w

ww

.eng

.aub

urn.

edu/

cent

er/n

cat/r

epor

ts/re

p02-

11.p

df

http

://w

ww

.poo

led-

fund

.org

/pro

ject

deta

ils.a

sp?i

d=11

&st

atus

=6)

Superpave and Mineral Aggregate Standards

The consensus aggregate standards incorporated in theSuperpave system, intially developed by a SHRPpanel, were derived from industry practices and earlierresearch and were not the product of explicitSuperpave research. While generally providingimproved performance, these standards greatly affect-ed the selection of aggregates for asphalt mixtures andhad major economic impact on public works agenciesand the aggregates supply industry. Particularly dis-turbing for both groups were instances, few in numberbut large in consequence, where aggregate suppliesknown to yield asphalt mixtures with superior per-formance could not meet the new standards.

Discussion on amending the consensus standardsbegan as soon as the Superpave research was complet-ed in 1993 and some project-by-project research toguide such amendments was initiated during theISTEA period. For example, in May 1998, NCHRPProject 9-14 (Investigation of the Restricted Zone inthe Superpave Aggregate Gradation Specification),began to investigate one of the more contentious of theconsensus standards.

The Superpave Committee’s Expert Task Group onMixtures and Aggregates developed a white paper on“Superpave Issues of Concern to the AggregateIndustry” to identify specific concerns amenable toresearch. This white paper led to the inclusion of anumber of aggregate research projects in the 2005Long-Range Plan. Over time these recommendationsresulted in NCHRP Projects 4-30 (Test Methods forCharacterizing Aggregate Shape, Texture, andAngularity), 9-14 (Investigation of the Restricted Zonein the Superpave Aggregate Gradation Specification),and 9-35 (Aggregate Properties and Their Relationshipto the Performance of Superpave-Designed HMA: ACritical Review). Other research already under way,such as 9-14, was subsumed into the plan.

These projects are reducing reliance on the consensusstandards, improving the understanding of aggregateproperties critical to performance, and eliminating thearbitrary exclusion of sources of aggregate supply.Issues regarding aggregate standards had stalled thedeployment of the Superpave mixture design stan-dards in certain locales. Had this research not beenundertaken, that situation would have continued.

This research addressed Goals 3 and 4

Superpave and Quality Control and Acceptance

NCHRP Project 9-07 (Field Procedures andEquipment to Implement SHRP AsphaltSpecifications) initiated the integration of Superpavewith construction quality control procedures. Thisproject developed a quality control/quality acceptance(QC/QA) plan in AASHTO standard format for hotmix asphalt paving projects incorporating Superpavemix designs. The objectives of this research were to (1)establish comprehensive procedures and, if required,develop equipment for at the asphalt plant and lay-down site to ensure that asphalt pavements meet theSHRP performance-related specifications and (2)develop a framework for a training program for quali-fying technicians to accomplish the QC/QA field pro-cedures developed.

The final report was published as NCHRP Report 409,“Quality Control and Acceptance of Superpave-DesignedHot Mix Asphalt, and formed the basis for developmentof PP52-05, Developing a Quality Assurance Plan forHot Mix Asphalt (HMA).”

This research also addressed Goals 3 and 4.

Calibration of Superpave Test Equipment

The last example of integration research is the dynam-ic angle validation (DAV) device, which facilitates thecalibration and comparison of Superpave gyratorycompactors. This device was developed by the FHWAthrough the NCHRP-supported project 90-01:Superpave Mix-Protocol Refinement and FieldValidation. The widespread availability and use ofSuperpave gyratory compaction devices was a mark ofthe success of Superpave deployment. Increasingly,these devices were being used for quality control andquality assurance purposes in asphalt pavement con-struction. Occasionally a dispute arose between anagency and a construction contractor as to whosedevice was “right” if the bulk specific gravity of speci-mens prepared with different devices varied unaccept-ably. Often the difference was attributed to mechani-cal problems with one of the devices or to incorrectcalibration of the internal angle of gyration. Use of theDAV now provides a way to directly compare the com-pactors involved in such disputes. When coupled witha sound maintenance regimen, the DAV can also beused to keep compaction devices properly calibrated,preventing future disputes. The dynamic angle valida-tion device is now available commercially. By provid-

20 SUPERPAVE: PERFORMANCE BY DESIGN

ing a reliable approach to dispute resolution and gyra-tory compactor calibration, the DAV facilitated thedeployment of Superpave. (Al-Khateeb 2002)

The DAV research addressed goals 2 and 3.

ACTIVITY TYPE 2: NEW RESEARCH

The SHRP research met its principal goal of deliveringa prototype system of materials selection and mixturedesign for hot mix asphalt that improved on proce-dures in use at the time. Between the time that thisgoal was first articulated in TRB Special Report 202 in1984 and the completion of the research in 1993, theworld of HMA pavement engineering had evolved.The two most significant changes were the rapidincrease in asphalt modification and the introductionof mechanistic principles into the structural design ofpavements. In today’s world, if Superpave is to bewidely used and deployed, it must work as well withthe new array of modified asphalt as it does with con-ventional asphalt binders. Also, the introduction ofmechanistic principles made it possible to explicitlyrelate certain characteristics of asphalt mixtures, cur-rently considered in the Superpave system, to pave-ment performance. This should permit the develop-ment of relationships between long-term performancemixture properties.

The SHRP program and other research revealedglimpses of how the Superpave system could bestrengthened and extended by new research not origi-nally contemplated as part of SHRP or not completedwhen SHRP closed its doors. New research initiated bythe FHWA under ISTEA and continued in theSuperpave 2005 plan under TEA-21seeks to turn theseglimpses into a vision. Fifteen of the 29 projectsincluded in the 2005 plan include “new” research ele-ments directed at strengthening and extending theapplication of the superpave system.

Superpave and Environmental Effects Models

For example, the original Superpave performancemodel system developed through SHRP incorporatedan environmental effects model as an integral compo-nent. This model provided the capability to predicttemperature and moisture conditions in the structureof the pavement, thus accounting for specific, long-term effects of climate on material properties andpavement performance. In 1996, a University ofMaryland research team reviewed the original SHRP

Superpave environmental effects model as a part of theFHWA Superpave Support and Performance ModelsManagement project and suggested that the predictivecapabilities of Superpave could be strengthened byreplacing the original model with an adaptation of anewer Integrated Climatic Model (ICM) developed forFHWA by (Dempsey, et al. 1985) The committee andothers incorporated this recommendation into the2005 plan. NCHRP project 9-23 (EnvironmentalEffects in Pavement Mix and Structural DesignSystems), scheduled for completion in 2005, seeks tocomplete this enhancement of the Superpave system.

Project 9-23 addresses Goals 2 and 3.

Other projects included in the plan are designed tostrengthen or extend Superpave in other areas.

Superpave and Asphalt Modification

Two research projects were conducted to extend theSuperpave binder specification to modified asphalt.These projects, the NCHRP-managed 9-10 (SuperpaveProtocols for Modified Asphalt Binders) and theFHWA-managed Project 90-7 (Understanding thePerformance of Modified Asphalt Binders in Mixes)were both initiated in the ISTEA period, but theSuperpave Committee recognized the research wasessential if the Superpave system was to be extended tothe testing of binders that include the ever-growingarray of asphalt modifiers and additives. The objec-tives of 9-10 were (1) to recommend modifications tothe Superpave asphalt binder tests for modified asphaltbinders and (2) to identify problems with theSuperpave mixture performance tests in relation tomixtures made using modified asphalt binders.Project 90-7 sought to establish the validity of testmethods developed as part of 9-10 through laboratorytesting and to develop new procedures to overcome theproblems identified in the 9-10 research. Project 9-10was completed in 2001 and 90-7 is continuing. A stateDOT supported pooled funds study is using resultsfrom accelerated pavement testing to complement thelaboratory testing conducted in project 90-7.

Both 9-10 and 90-7 addressed Goal 1.

A Simple Performance Test for Superpave

In concept, the Superpave system is a stepwise materi-als selection and design process. The performance of

21MEETING THE R& D GOALS OF SUPERPAVE DEVELOPMENT AND DEPLOYMENT

the resulting asphalt pavement is evaluated usingresults from mechanistically based tests and designprocedures applied at each step. No final “strength”test was included in the system. Many state DOTs andHMA suppliers saw the absence of such a test as a bar-rier to deployment. A survey of state DOT materialsengineers conducted by the Superpave Mixture andAggregate Expert Task Group assigned the highest pri-ority to the development of simple performance testsfor evaluating the resistance of Superpave-designedHMA to permanent deformation and fatigue cracking.

Work to define a new Superpave strength test was ini-tiated by FHWA and was absorbed into the 2005 planwhere it was restarted as part of NCHRP project 9-19.This work has been completed and a summary of thework to identify the simple performance tests selectedfor field validation has been published as NCHRPReport 465: Simple Performance Test for Superpave MixDesign.

NCHRP Report 465 identified several candidate testmethods that either alone or in combination might serveas a ‘simple performance test’ for the Superpave system.The objectives of the subsequent NCHRP Project 9-29were to design, procure, and evaluate test equipment toperform these tests for use in Superpave mix design andin HMA materials characterization for pavement struc-tural design. The project also required the constructionof a sufficient number of test devices from independentmanufacturers to conduct round-robin ruggedness teststo demonstrate the validity of the test method and testequipment. This work was completed in 2005 and theresults have been published as NCHRP Report 513:Simple Performance Tester for Superpave Mix Design:First-Article Development and Evaluation.

Adoption of the simple performance test for routine usein the Superpave mix design method will require theproduction of commercial test equipment. The 2005plan recognized the need to develop equipment specifi-cations, conduct equipment evaluations, test methodruggedness evaluations, and final procedure verification— all leading toward a national procurement for thestate DOTs and eventual widespread adoption and usein the HMA industry. These steps were successfully pio-neered by the Federal Highway Administrationthroughout the Superpave implementation process tobring many new test devices into routine use.

The work conducted under NCHRP 9-19 and 9-29 wasprimarily directed at Goal 2.

ACTIVITY TYPE 3: STANDARDS DEVELOPMENT

Engineering systems are defined by engineering stan-dards. Standards provide the common language forhighway engineers, materials suppliers, and construc-tion contractors to share requirements and expecta-tions for construction projects. They also provide thebenchmarks by which the quality of the design, thematerials, and the construction is measured.Unfortunately, the introduction of new technology ormethods can be delayed because no engineering stan-dards have been developed. This potential was recog-nized early in the Superpave deployment effort (and incorollary efforts for other SHRP derived technologies)and AASHTO, through the Highway Subcommittee onMaterials, published a set of “provisional” standard testmethods, materials specifications, and practices forSuperpave in 1994.

Because of recent trends toward improved quality con-trol of highway materials and the use of performancerelated properties, the Superpave implementationeffort has been subjected to scrutiny not applied toearlier HMA design procedures. Such intense scrutinycould have delayed general deployment. The use ofprovisional standards, however, turned a potential bar-rier into a mechanism to accelerate deployment andinitiate training. As state DOTs, equipment manufac-turers, material producers, contractors, researchersand other users of the provisional standards gainedexperience, they were able to relate that experience tothe Superpave expert task groups who, in turn, couldoffer advice on keeping the R&D focused on resolvingissues of standard practice, fostering deployment stillfurther. The AASHTO provisional standard signifi-cantly accelerated Superpave deployment.

Table 4 lists all of the provisional Superpave standardspublished by AASHTO. As laboratories gained experi-ence with the standards and provided data to completethe standards development process and as R&Dresolved concerns, the provisional standards were for-mally adopted as full standards, combined with otherstandards, or dropped because they were not needed orwere not being used on a regular basis. The currentdisposition of each provisional Superpave standard isalso shown on the table.

22 SUPERPAVE: PERFORMANCE BY DESIGN

23

TAB

LE 4

: Sup

erpa

ve-R

elat

ed A

ASH

TO P

rovi

sion

al S

tand

ards

, 199

4-20

05Su

mm

ary

and

Curr

ent S

tatu

s

Prov

isio

nal D

esig

natio

n*B

rief

Titl

eFi

rst P

ublis

hed

Curr

ent S

tatu

sCu

rren

t Des

igna

tion*

Rem

arks

MP

1Pe

rform

ance

Gra

ded

Asph

alt B

inde

rsJa

n-94

Full

Stan

dard

M 3

20Co

mbi

nes

MP1

and

MP

1a

MP

1aPG

Bin

der (

incl

udin

g m

odifi

ed)

Apr-

01Fu

ll St

anda

rdM

320

MP

2Sp

ec. f

or S

uper

pave

Mix

Jun-

97Fu

ll St

anda

rdM

323

PP 1

PAV

Acc

eler

ated

Agi

ngJa

n-94

Full

Stan

dard

R 28

PP 2

Long

/Sho

rt Te

rm M

ixtu

re C

ondi

tioni

ngJa

n-95

Full

Stan

dard

R 30

PP 3

Rolli

ng W

heel

Com

pact

orJa

n-95

Drop

ped

_

PP 5

Eval

. Mod

f. As

ph. S

yste

mJa

n-94

Drop

ped

_

PP 6

PG B

inde

rs V

erifi

catio

nJa

n-94

Full

Stan

dard

R 29

PP 1

9Vo

l. De

sign

HM

AJa

n-94

Drop

ped

_

PP 2

6Ce

rtif.

Bind

er S

uppl

iers

Jun-

97Fu

ll St

anda

rdR

26

PP 2

8Su

perp

ave

Volu

met

ric M

ix D

esig

nJu

n-98

Full

Stan

dard

R 35

PP 4

2Lo

w T

emp

Prop

s-Bi

nder

sAp

r-01

Prov

isio

nal

PP 4

2Pr

ov. S

tatu

s Ex

tend

ed 2

Yrs

.

PP 4

7Co

mpa

ring

2 Gy

rato

ries

May

-02

Prov

isio

nal

PP 4

7Pr

ov. S

tatu

s Ex

tend

ed 2

Yrs

.

PP 4

8Gy

rato

ry In

tern

al A

ngle

Jul-0

3Pr

ovis

iona

lPP

48

PP 5

2De

velo

p QA

Pla

n fo

r HM

AJu

l-05

Prov

isio

nal

PP 5

2

TP 1

Flex

ural

Cre

ep S

tiffn

ess

with

BBR

Jan-

94Fu

ll St

anda

rdT

313

24

MP=

Pro

visi

onal

Mat

eria

ls S

peci

ficat

ion

PP =

Pro

visi

onal

Pra

ctic

eTP

= P

rovi

sion

al T

est M

etho

d

M =

Mat

eria

ls S

peci

ficat

ion

R =

Rec

omm

ende

d Pr

actic

eT

= S

tand

ard

Test

Met

hod

TP 2

Quan

titat

ive

Asph

alt E

xtra

ctio

nJa

n-95

Full

Stan

dard

T 31

9

TP 3

Frac

ture

Pro

perti

es o

f Bin

der i

n Di

r. Te

nJa

n-94

Full

Stan

dard

T 31

4

TP 4

Dens

ity o

f HM

A Sp

ecim

ens

w/ S

GCJa

n-94

Full

Stan

dard

T 31

2

TP 5

Rheo

logi

c Pr

oper

ties

w/ D

SRJa

n-94

Full

Stan

dard

T 31

5

TP 6

Abso

rb. &

Des

orb.

Bin

d.Ja

n-94

Drop

ped

_

TP 7

Shea

r Stra

in a

nd S

tiffn

ess

w/ S

STJa

n-95

Full

Stan

dard

T 32

0

TP 8

HMA

Fatig

ue w

/ Rep

eat B

endi

ngJa

n-95

Full

Stan

dard

T 32

1

TP 9

Cree

p Co

mpl

ianc

e w

/ IDT

Ja

n-95

Full

Stan

dard

T 32

2

TP 1

0Th

erm

. Stre

ss R

estrn

.Ja

n-94

Drop

ped

_

TP 3

1Re

silie

nt M

odul

us o

f HM

AJa

n-95

Drop

ped

_

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3Vo

ids

in F

ine

Aggr

gate

Jan-

94Fu

ll St

anda

rdT

304

TP 3

4M

oist

ure

Sens

itivi

ty o

f HM

AJa

n-94

Drop

ped

_

TP 3

9M

odifi

ed R

ice

SGJa

n-95

Full

Stan

dard

T 20

9

TP 4

0%

Asp

halt

HMA

Jan-

95Dr

oppe

d_

TP 4

8Vi

cosi

ty w

ith R

otat

iona

l Vis

com

eter

Jan-

95Fu

ll St

anda

rdT

316

TP 5

3As

phal

t Con

tent

by

Igni

tion

Met

hod

Jun-

97Fu

ll St

anda

rdT

308

TP 6

1%

Fra

ct. C

oars

e Ag

g.M

ay-0

2Pr

ovis

iona

lTP

61

Prov

. Sta

tus

Exte

nded

2 Y

rs.

TP 6

2Dy

nam

ic M

odul

us o

f HM

AJu

l-03

Prov

isio

nal

TP 6

2

•TAB

LE 4

: Sup

erpa

ve-R

elat

ed A

ASH

TO P

rovi

sion

al S

tand

ards

, 199

4-20

05Su

mm

ary

and

Curr

ent S

tatu

s

Prov

isio

nal D

esig

natio

n*B

rief

Titl

eFi

rst P

ublis

hed

Curr

ent S

tatu

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rren

t Des

igna

tion*

Rem

arksCon

tinu

ed

Could targeted research discover the way to provideAmerica’s highway users with a smooth ride on a long-lasting pavement? From such a simple scenario grew aprogram of increasingly complex technical challenges.In addition to studying individual properties and char-acteristics of materials in varying combinations,researchers tested for effects of load and temperature,compaction and construction, developing, over a fewyears, a system by which smooth-riding pavementscould be designed for specific climate and load condi-tions. With the passage of The Intermodal SurfaceTransportation Efficiency Act (ISTEA) in 1991,Congress funded a campaign to implement the resultsof this research, and Superpave, along with otherSHRP products, was about to meet its public.

Implementation, however, encompasses a far broaderscope of activities than the word itself can conjure. Inthe case of Superpave, effecting change on a nationalscale would require gaining the attention, cooperation,active support, and financial commitment of people inleadership and technical roles in government; trans-portation agencies; industry, including manufacturers,suppliers, consulting firms, and associations; and aca-demia.

An array of techniques supported these efforts: con-vening expert task groups and technical workinggroups; supporting lead states as mentors; establishingregional centers to provide training and conduct con-tinuing research; encouraging partnerships withindustry and academia; pooling funds to buy equip-ment; developing provisional standards; implementing

round-robin testing; and developing certification pro-cedures for technicians. Some of these techniques werebeing tried for the first time in the highway communi-ty, but each reflected a responsive and flexibleapproach to technology deployment. An overview ofthe major implementation methods is provided hereto give dimension to the readers’ understanding ofhow Superpave came to be synonymous with hot mixasphalt. The timeline in Figure 1 (p. xii) shows the pro-gression of deployment activities.

IMPLEMENTATION DRIVERS

Lead State Program

The Lead State team, established by AASHTO in 1996as a means of developing and sharing practical expert-ise in the Superpave system, continued to serve as theprincipal champion of Superpave and to inform thework of the Superpave Committee until the programended in 2000. The Lead State team included Florida,Indiana, Maryland, New York, Texas, and Utah, as wellas members from the FHWA, the asphalt industry, theresearch community, and the Superpave Centers.

The Lead State team was very active in drafting provi-sional standards, explaining the underlying rationalefor change, and guiding the revised standards throughthe review and approval process. The team’s effective-ness, especially in this area, was due in large part to thesynergy created by cross-membership in key commit-tees. For example, team members were also members

25

FROM EXOTIC TO EVERYDAYLooking Back at the Technology Transfer Challenge

3

of the ETGs, the AASHTO Standing Committee onResearch and the Subcommittee on Materials, NCHRPresearch panels, national and regional forum steeringcommittees, and many others. Importantly, theseactivities received extensive support from the FHWA.

Annual national surveys conducted by the Lead Stateteam to determine where and how Superpave wasbeing implemented served the TRB SuperpaveCommittee both as an implementation tool and liter-ally as a developing roadmap. Results of the surveyswere sent to the Chief Engineer and the MaterialsEngineer in each state so that both management andoperating levels of state transportation agencies wereinformed of and challenged by the growing nationalacceptance of the technology. The surveys suppliedreason for undecided states to decide in favor of imple-mentation. As the implementation picture began todevelop from the survey, the committee could use theinformation to gauge its efforts and to better under-stand where there were barriers to implementation.

Additionally, members of the Lead State team devel-oped reports that became the basis for presentations atstakeholder meetings and journal articles that reachedmany audiences. These efforts resulted in confirmationand support for states that had adopted the technolo-gy and encouragement to those not yet committed.

The Lead State concept was an effective driver of tech-nology transfer. Early adopters of the technology couldmodel the implementation process and share whatthey had learned with those who came later. This waspossible because the Lead States received support, col-laborated with each other and with industry partnersand the FHWA, developed champions with authorityto commit resources, and received recognition for theirefforts. Many Lead State team members continued tocontribute to the work of the TRB SuperpaveCommittee throughout its lifetime, providing a rarecontinuity over a long-term project.

Expert Task Groups

Because Superpave technology involved a broad spec-trum of scientific and engineering disciplines (frombasic chemistry to construction management andfacilities maintenance), the TRB SuperpaveCommittee enlisted task groups with more focusedexpertise. The Mixture/Aggregate and Binder ExpertTask Groups provided input essential to designing

both the long-range research plan and the annualresearch programs.

The ETGs were organized in 1999 to provide technicaladvice on mixture and aggregate issues; monitor theFHWA Superpave technical activities related to mix-ture and aggregate; identify potential improvements tomixture and aggregate specifications and standard testmethods; identify needed standards; and discussemerging issues.

Since that time, the Binder ETG has advised theSuperpave committee on specifications that relatebinder selection to pavement performance, includingnearly all unmodified binders and an increasing num-ber of modified binders. The intent to include in thespecification as many binders as possible without ref-erence to modification type, chemistry, or brand namehas made this task one of the most complex elementsof Superpave and has been the primary focus of theBinder ETG.

Perhaps the most important role of the ETGs was facil-itating the transition from research findings to stan-dard specifications. Working with the AASHTOSubcommittee on Materials, the ETGs kept researchand development focused on resolving issues of stan-dard practice. More than 30 Superpave related stan-dards were issued by AASHTO and most were laterconverted to permanent status when states accumulat-ed enough experience.

At a time when state DOTs are experiencing a contrac-tion of technical staff, the ETGs have filled a void in theprocess of converting research into standard practice.A frequently voiced concern expressed by technicalprofessionals among both agencies and industrygroups is that completion of Superpave developmentwill lead to renewal of the void.

User/Producer Groups

The five regional asphalt user-producer groups alsoplayed a key role in the Superpave implementationeffort. Representing the materials-producing industry,asphalt refineries, paving contractors, and highwayagencies, the user-producer groups outlined strategiesfor adopting the Superpave system on a regional basis.They worked to encourage standardized specifications,binder grade selection processes, and acceptance plans.Additionally, the groups provided a forum for dis-

26 SUPERPAVE: PERFORMANCE BY DESIGN

cussing common concerns and arriving at workablesolutions. Local user-producer groups were encour-aged as focal points for training and materials testing.

A lead states format was developed within the user-producer groups so that expertise could be sharedamong the partners. For example, binder equipmenton loan from FHWA was installed in Indiana, whereDOT staff were trained in its use and later held train-ing sessions for other members of the user-producergroups. Indiana’s laboratory was also made availablefor materials testing. Minnesota was a lead state indeveloping an implementation plan encompassingvolumetric principles, field verification, process con-trol, compaction, and National Quality Initiative prin-ciples. The Rocky Mountain UPG purchased a trailerso that loaned binder equipment could be taken toeach state for six weeks. Four binders were tested ateach location to establish a basis for comparisonamong states.

This collaborative approach helped to spread expertiseand address practical issues more uniformly thanmight have been possible without user/producergroups.

TRAINING AND TECHNOLOGY TRANSFER

Transferring technology from research labs to job sitesacross North America is an enormous undertakingthat is itself benefiting from innovative techniques.Opportunities to learn about the Superpave mixdesign system have been offered by a range ofproviders in a variety of settings to students with anequally diverse range of backgrounds. Training andtechnology transfer techniques have included tradi-tional class room and laboratory training, on-sitetraining, mobile laboratories, distance learning andelectronic information exchange, certification pro-grams and traditional outreach activities such as con-ferences and publications. Most of these activitiesbegan during the early days of implementation andhave continued during the tenure of the SuperpaveCommittee, while others are currently in development.

Traditional Classroom and Laboratory Training

The five Superpave Centers (see sidebar) established in1995 have been an essential means of transferring

technology. Each center represents a partnershipbetween the FHWA, the host state, and an engineeringuniversity in that state to establish regional centers ofexpertise that would facilitate Superpave implementa-tion. Start-up funding and mixture testing equipmentwere provided by FHWA. The remainder of requiredfunding had to be generated by each center, with theintention of eventually becoming self-supporting. The

27FROM EXOTIC TO EVERYDAY: A Look Back at Technology Transfer

SUPERPAVE CENTERS

North Central Superpave Center Indiana Department of Transportation Building 1205 Montgomery Street, Box 2382West Lafayette, Indiana 47906(765) 463-2317 http://bridge.ecn.purdue.edu/~spave/

Northeast Superpave Center Northeast Center of Excellence for Pavement Technology The Pennsylvania State University201 Transportation Research BuildingUniversity Park, PA 16802(814) 863-1903 http://www.superpave.psu.edu

South Central Superpave CenterTexas A&M UniversityTTI/CE Building, Suite 508College Station, TX 77843-3135(409) 845-9965http://tti.tamu.edu/inside/centers/scsc.stm

Southeastern Superpave CenterAuburn University277 Technology ParkwayAuburn, AL 36830(334) 844-6228 http://www.eng.auburn.edu/center/ncat/ssc/ssc.html

Western Regional Superpave CenterUniversity of Nevada at RenoReno, NV 89557-0179(775) 784-6565http://www.wrsc.unr.edu/

funding mechanisms pursued by the individual centersvaried somewhat but typically included some supportfrom participating states, research funding, and train-ing income.

Thousands of engineers, managers, technicians, bothagency and industry personnel, have received trainingfrom the Superpave Centers over the last 10 years. Thenumber continues to increase as new people join theworkforce and as research results in further refine-ments to processes. Courses range from 2-hour man-agement overviews, through half-day sessions on thegyratory compactor, to two-week hands-on bindertesting and mix design training programs. Similarclassroom and lab training is also available at theNational Asphalt Training Center operated by theAsphalt Institute in Lexington, Kentucky. At theNational Center for Asphalt Technology (NCAT) atAuburn, Alabama, nearly 300 instructors have takenthe Professor Training Program in Asphalt Technologyand many more students have completed HMA cours-es for undergraduates.

Both the Superpave Centers and the FHWA’s trainingarm, the National Highway Institute, provide instruc-tors for training courses at the client’s site. The NHIhas also developed course materials that can be madeavailable for other organizations to conduct training.

Industry associations such as NAPA, the AsphaltInstitute, and the state asphalt paving associations allhave been sources of training sessions and resourcematerials from the early days of implementation. Asample survey conducted by the Expert Task Groupfor Communications and Training in 2002 found asmany as 10 different sources for training and certifi-cation materials.

Job-Site Training

The FHWA equipped mobile trailers as asphalt pave-ment mixture labs to provide on-site field testing tovalidate equipment and evaluate mixes while provid-ing state DOT and construction personnel withhands-on training. The mobile laboratories are stud-ies in multi-tasking. In addition to providing on-the-job training to agency and contractor personnel,quality control data valuable to the specific construc-tion project were collected and, as the labs weremoved from project to project, data were collected

about the normal variation in Superpave test meth-ods. These data proved valuable as AASHTO testmethods were refined.

The mobile laboratories were also made available toindustry conferences, technology showcases, universi-ties, and DOT offices. The mobile labs, updated withthe latest performance-testing equipment, still delivernew technologies to the states.

Distance Learning and Electronic Information Exchange

The National Highway Institute has supported super-pave deployment from its early days, offering coursesthroughout the country. More recently NHI began tooffer hot mix asphalt classes through Web confer-ences and on-line sites as a complement to its moretraditional course offerings.

Other sophisticated instructional options are beingdeveloped by researchers at NCAT and the Universityof Washington with support from NAPA. Interactivetraining materials on CD will help the current gener-ation of asphalt technicians and pavement engineersdesign for performance. One CD provides a com-plete overview of HMA technology using movieclips, animation, topic search capability, and glossarylinks. Another product, the Virtual SuperpaveLaboratory, uses computer-based learning tools toteach laboratory procedures and data analysis. Athird product, HMAView, is supported through apooled fund effort. It is a Web-enabled applicationthat allows for real-time acquisition of mix design,field construction, and performance data. The datacan be shared across divisions to inform decisionmaking at various organizational levels. (More infor-mation about these products is available from thecontacts listed in the box.)

Certification

Certification of asphalt laboratory technicians is some-times required by DOTs as a device to ensure thatagency and contractor staff engaged in materials selec-tion and mixture design have a proper understandingof the specifications and test methods involved in hot-mix asphalt materials selection and mixture design,including the Superpave system and the associated test

28 SUPERPAVE: PERFORMANCE BY DESIGN

methods. It also serves as a driver to agencies, contrac-tors, and the technicians themselves to provide or seek training. A 2005 survey by the AASHTOSubcommittee on Materials found that 16 of 41responding DOTs require certification for asphaltbinder quality control technicians. Survey responsesindicate that certification training and testing is pro-vided by the DOT in 4 of the 41 responding states, bythe AASHTO Materials Reference Laboratory in 5states, and through regional certification programssuch as the Northeastern Technician Training andCertification Program, which provides training atPenn State University and the University ofConnecticut, in 7 states.

Variation in training materials is an important factorin discussions about certifying technicians andwhether certification could be reciprocal among states.The FHWA’s Transportation Curriculum CoordinatingCouncil (TCCC) seeks to identify the various techni-cian certification programs offered across the countryand provide curriculum guidance. In recent years,TCCC leaders have met periodically to review

Superpave research findings so that appropriate train-ing materials could be cited in this curriculum advice.

Outreach

Traditional outreach activities such as conferences,workshops and publications have been often and effec-tively used to convey information about Superpave tovarious audiences. Superpave has figured prominent-ly in regular conferences such as the TRB AnnualMeeting and the Association of Asphalt PavementTechnologists. Special presentations on the develop-ment and deployment of Superpave were regularlyincluded in meetings and conferences organized byAASHTO, the National Asphalt Pavement Association,the Asphalt Institute, and the National Stone, Sand,and Gravel Association. Periodically, The FHWA, TRB,AASHTO and industry organizations collaborated insponsoring special Superpave Conferences. The firstof these was held in Reno, Nevada, in October of 1994.The most recent was held in Nashville, Tennessee, in2003, in conjunction with the World of AsphaltExposition.

Workshops incorporating training elements werealso a common technique to introduce the Superpave

concept to users and to track the evolution of the system as improvements were made. Workshops werefrequent additions to meetings sponsored by theregional asphalt/user producers groups or theSuperpave Centers.

Conferences and workshops provide the human inter-action that fosters learning and leads to evolutionaryimprovements to engineering systems such asSuperpave. Publications, however, whether print orelectronic, provide the system with a documentaryfoundation. In the past 10 years, hundreds of reports,syntheses, manuals, and guides documenting the useand evolution of Superpave have been published. Asmall sample of significant references published insupport of Superpave deployment includes:

Asphalt Institute SP-1 Superpave Performance Graded AsphaltBinder Specification & Testing, 3rd ed. 2003.

Asphalt Institute SP-2 Superpave Mix Design, 3rd ed. 2001.

FHWA-RD-01-052 Mixture Design Guide, Westrack ForensicTeam Consensus Report. 2001.

29FROM EXOTIC TO EVERYDAY: A Look Back at Technology Transfer

SUPERPAVE RESOURCES

Hot Mix Asphalt for the UndergraduateProfessor Training Course

Information about these courses is available fromNCAT at www.eng.auburn.edu/center/ncat

HMAViewFor information about HMAView contact GeorgeWhite, University of Washington at 206-685-7198 orGloria Burke, Asphalt Team Leader, Maryland StateHighway Administration at 800-477-7453To view HMAView live, visit the Web site athttp://hotmix.ce.washington.edu/MD

A Guide for Hot Mix Asphalt Pavementand the Virtual Superpave Laboratory areavailable from NAPA.National Asphalt Pavement Association5100 Forbes Blvd.Lanham, MD 20706888-HOT-MIXX (468-6499)

FHWA–RD-02074 Understanding the Performance of ModifiedAsphalt Binders in Mixtures: Low Temperature Properties. 2002.On the Web at: http://www.fhwa.dot.gov/pavement/pub_details.cfm?id=291

NCHRP 452: Recommended Use of Reclaimed Asphalt Pavementin the Superpave Mix Design Method: Technician’s Manual. 2001.

NCHRP 455: Recommended Performance Related Specificationfor Hot-Mix Asphalt Construction. 2002.

NCHRP 459: Characterization of Modified Asphalt Binders inSuperpave Mix Design. 2001.

NCHRP 464: The Restricted Zone in the Superpave AggregateGradation Specification. 2001.

NCHRP 465: Simple Performance Test for Superpave Mix Design.2002.

NCHRP 478: Relationship of Superpave Gyratory CompactionProperties to HMA Rutting Behavior. 2002.

NCHRP 513: Simple Performance Tester for Superpave MixDesign: First Article Development and Evaluation. 2004.

NCHRP 530: Evaluation of Indirect Tensile Test (IDT) Proceduresfor Low-Temperature Performance of Hot Mix Asphalt. 2004.

NCHRP 531: Relationship of Air Voids, Lift Thickness, andPermeability in Hot-Mix Asphalt Pavements. 2004.

Audience Diversity: An Additional Challenge

Most technology transfer and training efforts are craft-ed to reach audiences that share common backgroundsand levels of relevant expertise. The deployment ofSuperpave, however, demanded technology transfer tomultiple audiences whose members had widely vary-ing technical backgrounds.

As Superpave became the standard hot mix asphaltdesign method for state DOTs, more local transporta-tion agencies needed to develop expertise in its use.This precipitated new outreach and training efforts.Case studies and other materials were prepared underthe direction of the Communications and TrainingETG that could be the focus of workshops specificallyfor local agencies. The first workshop was held duringthe 8th International Low-Volume Roads Conferencein Reno in 2003.

The Communications and Training ETG has suggestedthat such collaborations should be continued andexpanded in the future. For example, communicationwith the FHWA’s Transportation CurriculumCoordinating Council can ensure that research find-ings are included in new training materials. The sec-ond recommendation is participation in the FHWA’sCommunity of Practice. This Web-based tool couldbecome a dynamic center for learning best practicesand moving HMA technology forward through sharedinterests. Participation in the Community of Practicewould require commitment of funds and staff, as wellas active means of engaging participants. An e-mailedbulletin or newsletter would be one approach to this.

SUMMARY

Innovation is often an effective teacher and valuablelessons were learned from evaluating the techniquesused to implement Superpave. A principal lesson wasto take a measured approach to widespread implemen-tation of what was essentially a prototype product.Resolving early challenges with test methods, equip-ment design, and aggregate issues in the lab or on testtracks would undoubtedly have bolstered early accept-ance of Superpave. Not all problems will arise undertest conditions, of course, but refining procedureswhere possible before deployment eliminates somebarriers. This is a correlary to another lesson, whichhad to do with including potential product users inearly discussions and decision making. Althoughincluding stakeholders was a guiding principle of theentire SHRP research and implementation effort, itwas difficult to identify all affected groups and toensure balanced influence among group members.

Ultimately, implementation efforts succeeded wherebarriers were eliminated. Congress funded implemen-tation at nearly the same level as the initial research,risk-averse public agencies responded when mentorsstepped forward, decision makers believed in thepotential payoff and were willing to contribute sup-port. These actions created a cultural shift that encour-aged individuals at the operating level in all states totake implementation risks they might not otherwisehave taken.

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31

No engineering system can remain static for long.Situations will arise where reliability is compromisedor opportunities may surface where reach and effec-tiveness can be extended or enhanced. The SuperpaveCommittee recognized this eventuality and, as it devel-oped and prosecuted the 2005 long-range plan, offeredperiodic recommendations regarding deficiencies oropportunities.

An example of such a recommendation can be foundin the sixth letter report (August 10, 2001), of the TRBSuperpave Committee. The committee recommendedthat the FHWA pursue the research that led to thedevelopment of the Dynamic Angle Validation Devicethat is now used to calibrate the internal angle of gyra-tion of Superpave gyratory compactors (SGCs). Whenthe SGC was first included in the Superpave system, itwas not anticipated that the HMA suppliers andpaving contractors would be using these compactorsfor construction quality control purposes and no tech-nique to compare agency and contractor SGCs wasprovided. Over time it became evident that such atechnique was needed if the deployment of the systemwas to continue. Similarly, when research conductedunder NCHRP Project 9-14 (Investigation of theRestricted Zone in the Superpave Aggregate GradationSpecification) concluded that the “restricted zone” thatcontrolled the proportion of fine aggregate included inan HMA materials design was redundant if all otherSuperpave aggregate standards were met, the commit-tee recommended that the restriction be deleted fromthe AASHTO Superpave Standards (Letter Report 7,November 29, 2001).

The committee also offered recommendations forother research to enhance the Superpave System or toimprove the performance of HMA pavements that isstill incomplete or was never initiated because of fund-ing or time constraints. These recommendations aresummarized below as a reference for designers offuture hot mix asphalt research programs. Althoughthe Superpave system has obviously been deployedwith great success, all of the original research objec-tives have not been completely met. Reliability ofaspects of the system can still be enhanced and theprogress of pavement research has opened new oppor-tunities to further improve the design and construc-tion of hot mix asphalt pavement.

MOISTURE DAMAGE

Moisture damage, also known as asphalt stripping ormoisture susceptibility, refers to the loss of bondbetween asphalt binder and aggregate in the presenceof moisture and traffic loading. Moisture damage is acomplex phenomenon resulting from multiple physi-cal and chemical interactions among asphalt cements,mineral aggregates, imposed loads, and environmentalconditions. The fundamental mechanisms involved inthese interactions are still not well understood andstripping continues to be a major cause of distress inasphalt pavements. In its third letter report (December13, 1999) the TRB Superpave Committee recommend-ed a two-pronged approach for future research.

1. Additional research on developing a physical testshould recognize that any testing regime must sim-

UNANSWERED QUESTIONSA Need for Continuous Improvement

4

ulate the conditions of service, in an acceleratedmanner, of specific asphalt-aggregate mixtures toaccurately quantify the overall potential for mois-ture damage.

2. Because the fundamental mechanisms that leadto moisture damage are still not well understood, itwould be prudent to support research into theunderlying chemistry and physics of the problem.Any advance in basic understanding of this complexphenomenon would lead to improvements in phys-ical tests used to quantify moisture damage poten-tial of a mixture and would improve screening ofthe constituent materials.

Subsequently, the FHWA and the Western ResearchInstitute of Laramie, Wyoming, agreed to pursuechemical and physical research into possible mecha-nisms of moisture damage. NCHRP Project 9-34(Improved Conditioning Procedure for Predicting theMoisture Susceptibility of HMA Pavements), recom-mended by the committee, was initiated in 2002 todevelop an improved conditioning procedure based onthe SHRP-developed Environmental ConditioningSystem for evaluating the moisture susceptibility ofcompacted HMA in combination with the SuperpavePerformance Test validated in NCHRP Project 9-19(Superpave Support and Performance ModelsManagement). As yet this research is incomplete.While neither effort may prove to be the final answer,they represent a significant start in finding that answer.

INTEGRATION WITH PAVEMENT DESIGN MODELS

The goal of integrating flexible pavement structuredesign and asphalt materials mixture design throughcommon, mechanistically based performance modelsantedates the Strategic Highway Research Program.With the introduction of Superpave, the achievementof that goal drew closer. Now, the opportunity toaccomplish this goal seems to be in reach. Theprogress in NCHRP Project 9-19 toward test methodsthat can effectively characterize significant perform-ance-related materials properties of asphalt mixturesand the progress toward models that can predict long-term performance of flexible pavements in Project 1-37a (Development of the 2002 Guide for the Design ofNew and Rehabilitated Pavement Structures: Phase II)

put new components in place. Even before these twoprojects were completed, the Superpave Committeesaw an opportunity to validate and integrate the find-ings of these two independent efforts. In its fifth letterreport (11/27/2000) the committee recommended thatthe investigation of this opportunity be undertakenpromptly, even if it meant delay in the development ofthe more advanced materials characterization models.From this recommendation, the AASHTO StandingCommittee on Reasearch approved NCHRP Project 9-30 (Experimental Plan for Calibration and Validationof HMA Performance Models for Mix and StructuralDesign). This project has been completed and a fol-low-on project (9-30A) on calibration of rutting mod-els for HMA is pending. The coordination of theseresearch projects is an intimation of the coordinationof pavement structural design and materials designthat will be possible in the future.

In the same letter report, the committee recommend-ed coordinating this research with NCHRP Projects 9-20 (now completed) and 9-22 (still active), which areinvestigating performance-related specifications forhot mix asphalt. If factors significant to performancecan be specified in pavement design and/or mixtureselection and design and then controlled during con-struction, a major step toward enhanced performancebecomes possible.

The development of new, more sophisticated, mecha-nistic performance models was not crucial to thedeployment of the Superpave system in its currentform. Therefore the committee did not recommendadditional model development as part of theSuperpave deployment effort. However, the committeedoes see benefit in the development of calibrated,valid, fully mechanistic HMA performance models.Except in special cases, models of such complexity willprobably not be used directly in pavement design.However, information derived from these models willlead to improved design procedures. This work willalso lead to the identification of critical factors that canbe controlled or influenced by materials suppliers andconstruction forces and so result in improved con-struction quality control and dependable long-termperformance warranties. The pavement performancemodules incorporated into asset management systemswill also be influenced. Asphalt pavement perform-ance models in use today still contain many empirical-ly based components. Such models cannot adjust tonew materials or conditions. When applied outside

32 SUPERPAVE: PERFORMANCE BY DESIGN

their inference space, these models can yield unde-pendable or even nonsensical predictions.

For these reasons, the committee’s ninth letter report(January 7, 2003) recommended that the FHWA pur-sue development of fully mechanistic performanceprediction models as an element of its long-rangeinfrastructure research program.

MINERAL AGGREGATE RESEARCH

Mineral aggregates are the principal components ofhot mix asphalt. Any program of continuous improve-ment will find aggregate research to be a continuingnecessity. In the fifth letter report (11/27/00) theSuperpave Committee provided a white paper onHMA aggregate research developed by an ad hoc taskforce of the ETG on Mixtures and Aggregates. Thecommittee recommended that several research needscited in the white paper needed to be completed as partof the Superpave deployment effort. These recom-mendations led to NCHRP Project 9-35 AggregateProperties and Their Relationship to the Performanceof Superpave-Designed HMA: A Critical Review (nowcompleted) and NCHRP Project 4-30A Test Methodsfor Characterizing Aggregate Shape, Texture, andAngularity (active).

Many other HMA-related research needs identified inthe white paper remain unaddressed, however, and areworthy of consideration in future research programsaddressing hot mix asphalt. (The white paper beginson p. 34 of the fifth letter report, which is online athttp://gulliver.trb.org/publications/sp/superpave.final.letter_5.pdf)

ASPHALT MODIFICATION

It has always been a goal to make the Superpave system“blind” to modifiers and additives. In other words, thesystem would be as reliable in characterizing criticalproperties of asphalt modified with any additive as it iswith unmodified asphalts. Because various additivesand modifiers rely on different mechanisms to modifythe physical properties of asphalt, this is a challengingassignment and no other topic was addressed as fre-quently in the letter reports of the SuperpaveCommittee. Research on methods or procedures to

reliably extend the Superpave performance grade spec-ification was initiated by FHWA and the NCHRP dur-ing the ISTEA period. Since its organization, theSuperpave Committee has consistently supported thisresearch objective. In the fifth letter report, for exam-ple, the committee recommended continued fundingbe provided for the FHWA-managed study 90-07 toevaluate new or modified test methods to reliablycharacterize the properties of modified asphalts. Thecommittee also advocated the creation of a state DOTpooled fund to use accelerated pavement testing toestablish the relationship of pavement performance tothe properties measured by the new tests.

Although incomplete, the FHWA research has identi-fied some promising test methods to characterize thehigh-temperature behavior (i.e. rut resistance) ofmodified asphalts, but much remains to be done.There will always be new modifiers. The need for a setof laboratory test methods to adequately assess anymodifier’s potential to improve pavement perform-ance is vitally important.

SUPERPAVE FOR LOCAL ROADS

Among state DOTs, Superpave has largely supplantedother systems of hot mix asphalt materials selectionand mixture design. The state DOTs, however, direct-ly control only about 20% of the nation’s 2 millionmiles of asphalt surfaced roadways. The remainder areunder the custody and control of upwards of 15,000local agencies. Among these local agencies, however,Superpave deployment is lagging. The responses to thecommittee’s recent survey on Superpave usage indicat-ed that local highway agencies were regularly specify-ing HMA purchases using the Superpave system inonly 20 states. This lag in deployment is not unexpect-ed. New highway technologies are often introduced atthe state level and then disseminated among localagencies at a much slower pace.

In the case of Superpave, however, this situation isleading to adverse consequences for many local agen-cies. As deployment among state DOTs advanced andoutpaced deployment among local agencies, the HMApaving industry has either had to support dual systemsor supply Superpave selected materials to local roadsagencies uninformed about the different performancecharacteristics of these materials. Because Superpavemixes are designed for specific traffic conditions, HMA

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mixes designed for state highways, but supplied tolocal agencies, may be too coarse, too stiff, and tooshort on asphalt content to perform well on residentialstreets or farm-to-market roads.

Extending the deployment of new technology to thelocal roads community is always challenging. Thiscommunity is very large, diverse in its needs, and gen-erally must manage a full array of public services, notjust roadways. It is unlikely that a single approach todeployment of Superpave among local agencies is to befound. Furthermore, until the true needs of localagencies are known and potential barriers identified,no effective strategy can be developed. The needs oflarge metropolitan areas will differ markedly from sub-urban and residential areas. Rural local roads agencieswill have a different set of needs altogether.

In its seventh letter report (November 29, 2001), theSuperpave Committee asked FHWA and AASHTO toconsider if a special technology transfer effort to intro-duce the Superpave system to local agencies was war-ranted. The committee itself undertook several tenta-tive steps in that regard. In March of 2003, the commit-tee organized an “ask the experts” booth as part of theWorld of Asphalt exposition in Nashville, Tennessee.Exposition attendees could learn about usingSuperpave in local roads situations from a group ofexperienced users. At the 8th InternationalConference on Low-Volume Roads in Reno, Nevada,the committee conducted a pilot technology transferworkshop for local agencies built around actual casestudies of Superpave applications for local roads. Thecase studies were contributed by county engineers inMaryland and New York.

In the eighth letter report (May 17, 2002), the commit-tee also recommended that AASHTO develop criteriaand design requirements for Superpave mixes suitable-for application on light duty roadways. The commit-tee’s recommendation forwarded a prototype specifi-cation suggested by the ETG on Mixtures andAggregates. This mix, with a smaller nominal maxi-mum-size aggregate, is more suitable for very thinoverlays than the coarser mixes typically specified bystate DOTs. AASHTO did amend the Superpave stan-dards along these lines in the 24th edition of it’s stan-dard specification. Criteria and requirements wereincluded for 4.25mm and 9.5 mm nominal to sizemixes (AASHTO, 2004).

The recent financial uncertainty associated with thesequence of short-term extensions of the federal aidsurface transportation authorization has inhibited thedevelopment of any national program of technologytransfer to local agencies. State DOTs and state asphaltpaving associations have made efforts in this regard,however. Examples include the Iowa DOT’s develop-ment of a Superpave manual for local roads and mate-rials developed by New York State DOT and theCornell Local Roads Program. In the absence of a uni-fied effort, however, deployment of Superpave amonglocal agencies will continue to lag and the potential useof inappropriate materials and mixtures on lower vol-ume roads will remain a problem.

CONSTRUCTION

Performance related specifications and materials qual-ity control and acceptance are the only constructionelements considered in the Superpave system. Thetechniques of delivery, placement, and compaction ofHMA are not addressed. However, construction relat-ed issues surfaced early in the Superpave deploymentprocess—tender mixes, low mat densities, new com-paction temperature requirements, handling of coars-er mixes, and segregation were among them. Fromtime to time, these issues reappear. It is not entirelyclear, however, if these problems are unique toSuperpave or systemic to HMA paving in general.Because poor construction can bring the best designsto naught, the committee remained cognizant of theseissues and, where useful, recommended actions toFHWA and AASHTO that aid in resolving them.

From issues reported to the committee members byexperienced paving contractors, it was evident thatcontractors and materials suppliers have encounteredvery real problems dealing with Superpave-designedasphalt mixes. In the great majority of instances, theseproblems have been satisfactorily resolved. Whilesome of the problems relate to construction techniqueand the need to adapt techniques to Superpave mixesand other new materials, most seem related to con-struction quality control and apply generally to mod-ern HMA paving. The Superpave Committee reachedno specific conclusions on this topic but did recom-mend that AASHTO and FHWA maintain dialoguewith the HMA construction industry regarding HMAconstruction.

HISTORY OF SUPERPAVE

In May of 2005, the AASHTO Board of Directors for-mally adopted the NCHRP research program for fiscalyear 2006. Included in that program is Project 9-42,History of Superpave and Its Implementation. In itseleventh letter report (April 8, 2005), the SuperpaveCommittee expressed its support for such a project onthe history of Superpave. In that letter, the committeestated:

Superpave is a research success story. The framers of theoriginal Strategic Highway Research Program shared avision that properly focused, high-intensity researchcould resolve growing concerns about unreliable per-formance of asphalt pavements. Now, as we approach theconclusion of the development and deployment programthat has put that research into practice, we note that thedocumentary background of Superpave is scatteredthrough more than 200 publications of at least six organ-izations. Even with the sophisticated capabilities of mod-ern library science, we feel this disorganized state willultimately prove injurious to the Superpave system andalso limit the lessons to be learned from the Superpaveexperience.

Superpave has enjoyed high visibility among theorganizations engaged in its deployment. Governmentand industry leaders were willing to invest theresources needed to secure the promised benefits. Asthe focused deployment effort draws to a close and thesystem blends into the engineering landscape, this pro-file might well change. Decisions about the applica-tion of Superpave to locally available materials, specif-ic materials designs, laboratory workload, and otherday-to-day issues will increasingly be made by individ-uals with no immediate familiarity with the back-ground of Superpave. These individuals will lack thetime and, in many cases, the training to consult themany technical references to determine if any particu-lar decision is at odds with the systematic nature ofSuperpave. A single reference that illustrates how andwhy the Superpave system is organized as it is will limitthe risk that would accompany otherwise uninformeddecisions.

From the outset of the Superpave deployment cam-paign, members of academia have long advised us thata sourcebook was also needed if Superpave was to beincorporated into undergraduate and technical school

curricula. Particularly for engineering undergradu-ates, the “why” of any engineering system is a key ele-ment of successful teaching. While primers exist thatdeal with aspects of Superpave, no single text capturesboth the research foundation and practical applicationof the system. The committee sees the prospectiveproject as a potential “sourcebook.”

Finally, because the Superpave Committee’s principalcharge was to coordinate the finalization of the deploy-ment effort, its greatest cause for concern is that thenovel approaches and devices used in this very success-ful technology deployment program are little docu-mented. Introduction of new technology systemsamong transportation agencies is always challenging.No lessons of successful deployment should gounrecorded. The brief exposition on technology trans-fer included in chapter 3 of this report only providesan indication of the innovative practices used toencourage the deployment of Superpave. The com-mittee members believe these techniques can be usedin other technology transfer efforts, but only if the rea-sons for their success are detailed.

A SUCCESSFUL CONCLUSION

In the preliminary research plans for SHRP, AASHTOexpressed its expectation of what the program’s asphaltresearch was designed to produce:

“…1) a specification for asphalt, with or without mod-ification, which is designed to produce a binder withdesired performance-based properties, and 2) amethod for combining asphalt and aggregate to pro-duce a mixture with desired performance-based char-acteristics.” (Page TRA 1-19, SHRP Research Plans,May 1986)

Under the rubric of Superpave, the SHRP researchfindings provided the building blocks of a prototypesystem to meet this goal. The deployment effort thatfollowed provided the mechanisms for evolution,enhancement, and implementation among the stateDOTs that converted the SHRP research results into arefined system that now forms the core of hot mixasphalt materials selection and mixture design specifi-cations used throughout North America.

As reported in chapter 1, currently 50 of the 52 mem-ber state DOTs of AASHTO have adopted the

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36 SUPERPAVE: PERFORMANCE BY DESIGN

Superpave asphalt binder selection procedures and 48are using the mixture design procedures. The non-user agencies have indicated plans to adopt bothaspects of Superpave in the near future. Never beforehas a single set of hot mix asphalt materials standardsbeen so widely used in the United States. Where theSuperpave system is used, states have reported extend-ed service life for asphalt pavements and reducedmaintenance costs. Little or no increase in the cost ofhot mix asphalt is attributable to adoption of theSuperpave system. Full integration of the Superpavesystem into standard hot mix asphalt practice by theend of 2005 was the stated goal of the TRB Superpave

Committee at its inception. Clearly this goal has beenmet as well.

Work remains, however. Research is continuing in anumber of areas, including moisture damage, testingof modified asphalts, mineral aggregates, and perform-ance testing. Additional research in other areas, such asadvanced performance models and construction qual-ity control is indicated. The apparent lag in deploy-ment and limited conversancy with Superpave amonglocal highway agencies indicates that the system is stillnot fully comprehended by potential users.

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Dempsey, B. J., Herlache, W. A., and A. J. Patel (1985), “The Climatic-Material-StructuralPavement Analysis Program” FHWA-RD-84/115 3 Federal Highway Administration, USDOT.See also:

Larson, G. and B. J. Dempsey (1997), “Enhanced Integrated Climatic Model Version 2.0.”DTFA MN/DOT 72114.

Larson, G. and B.J. Dempsey (2003), “EICM Software, Enhanced Integrated Climatic Model3.0 (EICM).” University of Illinois, Urbana.

First Pavement Constructed with SUPERPAVE, Focus, Strategic Highway Research Program,September 1992.

Gryzbowski, K., PRI Asphalt Technologies, Inc. A presentation by Thomas Harman, FHWA,to the Association of Modified Asphalt Producers in February 2005 reported Gryzbowski’sfindings on the use of Superpave Plus. The presentation is on the Web at:http://www.cahs.colostate.edu/cm/Asphalt%20Presentations%2005/Session_02/Harman/Superpave%20Update%20Feb%2005%20-%20Harman%20LG_files/frame.htm

Al-Khateeb, G., Paugh, C., Stuart, K., Harman, T., and D’Angelo, J., 2002. Target andTolerance Study for the Angle of Gyration Used in the Superpave Gyratory Compactor.Federal Highway Administration. Available on the Web at:http://www.tfhrc.gov/pavement/asphalt/labs/mixtures/target.htm

Little, D.N.; Memmott, J.; McFarland, F.; Goff, Z.; Smith, R.; Wootan, C.V.; Zollinger, D.;Tang, T.; Epps, J., 1997. Economic Benefits of SHRP Research. Texas Transportation Institute.Available in PDF from TRIS Online at: http://trisonline.bts.gov/search.cfm.

Mack, P.J., and Dunn, R.J., 2001. Superpave Implementation and Needs Assessment. NewYork State Department of Transportation, Technical Services Division, and Federal Highway.

REFERENCE LIST

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Administration, New York Division. Available on the Web at: http://leadstates.transporta-tion.org/SP/sp_needs.pdf

Tanden, V., and Avelar, I., 2002. Superpave Adoption by State Highway Agencies:Implementation Status and Assessment. Federal Highway Administration. Report NumberDTFH-02-104-1.

Transportation Research Board Special Report 261: The Federal Role in Highway Research andTechnology, 2001. National Research Council. National Academy Press. Available through thebookstore at www.TRB.org.

Joseph A. Mickes, ChairmanEnergy Absorption Systems, Inc.

Mr. Mickes holds a BS (engineering), 1958, from the Missouri School of Mines (now theUniv. of Missouri, Rolla). He is a registered professional engineer with more than 40 yearsof highway engineering experience. Mr. Mickes currently works for Energy AbsorptionSystems, Inc., a highway safety technology supply firm now part of Quixote SafetyCorporation. He was formerly Director and Chief Engineer of the Missouri Department ofTransportation. He has served as Chairman of the TRB SHRP Committee and as a mem-ber of the TRB Executive Committee and the TRB Executive Committee’s Subcommittee forNRC Oversight.

David A. Anderson Professor of Civil Engineering (Emeritus)Pennsylvania State University

Dr. David A. Anderson is emeritus professor of civil engineering at the Pennsylvania StateUniversity and director of the North East Center of Excellence for Pavement Technology atthe Pennsylvania Transportation Institute. Dr. Anderson has worked on the StrategicHighway Research Program (SHRP) asphalt program in the development of new specifica-tions and tests for asphalt cement binders. He was responsible for leading the Penn Stateteam of faculty and graduate students that developed the test methods and specifications forthe new SHRP binder specification. He is particularly interested in the development of testmethods and equipment, the physical characterization of civil engineering materials, andthe development of relationships between material properties and in-service performance.Dr. Anderson has extensive experience with accelerated loading facilities as well as test tracksand has supervised a number of field studies in which the performance of different aggre-gates, mixture designs, and pavement sections were evaluated. Other research interests andprojects include pothole repair materials and methods, seal coat performance, skid resist-ance, flyash utilization, and pavement instrumentation. Dr. Anderson has authored morethan 120 research reports and refereed publications and has been principal or primaryinvestigator on research projects totaling more than $15 million.

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TRB SUPERPAVE COMMITTEE BIOGRAPHICAL INFORMATION

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Martin F. Barker EngineerCity of Albuquerque, NM

As the senior roads and streets manager for the City of Albuquerque, Mr. Barker is respon-sible for a substantial program of reconstruction or overlay of asphalt pavements. He hasinitiated the use of Superpave in this program and provides an experience base useful indeveloping Superpave technology transfer schemes suitable for other municipal transporta-tion agencies.

Jed S. Billings (Served through 2004)President and Chief Executive OfficerFNF Construction, Inc.

Mr. Billings is the president and chief executive officer of FNF Construction, Inc., a majorhighway construction firm operating in Arizona, New Mexico, and California. He has heldthis position since 1986. Mr. Billings has more than 30 years of asphalt pavement construc-tion experience. His firm has been eager to introduce innovation into construction prac-tices. He has direct experience with asphalt rubber and Superpave. His firm works both instates that are attempting to deploy the Superpave system and in those resisting its introduc-tion, affording him a unique view of the deployment process. Mr. Billings has been activein leadership roles in a number of local and national industry associations including theNational Asphalt Pavement Association, the American Road and Transportation BuildersAssociation, and the Associated General Contractors.

Frank L. Danchetz Arcadis G&M, Inc.

Mr. Danchetz holds a BS in civil engineering from the Georgia Institute of Technology andis a registered Professional Engineer. He was Chief Engineer of the Georgia DOT, where hewas responsible for the management of all planning, design, construction, and maintenanceactivities. Past experience also includes environmental assessment and impact mitigation,rights-of-way management, and service as the departmental liaison to Congress. Mr.Danchetz served on the Standing Committee on Highways of AASHTO and was a memberof the Research and Technology Coordinating Committee and the Committee for a FutureStrategic Highway Research Program, both NRC-appointed committees of TRB.

Fred M. Fehsenfeld, Sr.Chairman of the Executive Committee, Heritage Group

Mr. Fehsenfeld holds a mechanical engineering degree from Purdue University. He is cur-rently chairman of the Heritage Group, which consists of 25 companies nationwide withmore than 3,800 employees. This group of companies is involved in petroleum marketing,oil refining, road building, aggregate production, and environmental management, with astrong corporate emphasis on research and development. Mr. Fehsenfeld has held manyvoluntary posts within the Asphalt Institute, including Director and Chairman, and has heldsimilar positions in other petroleum industry associations. He is currently a member of theAssociation of Asphalt Paving Technologists, the Technical Oversight Committee of theNational Center for Asphalt Technology, TRB’s standing technical Committee on GeneralAsphalt Problems, the National Asphalt Pavement Association (NAPA), and the Asphalt

Institute (AI). He has been named to NAPA’s “Hot Mix Hall of Fame” and AI’s “Roll ofHonor” for his industry contributions and has received the Distinguished EngineeringAlumni Award from Purdue University. He is the author of a number of professional papersand holds several industrial patents.

John E. Haddock Assistant Professor of Civil EngineeringPurdue University

Dr. John E. Haddock is currently an Assistant Professor of Civil Engineering at PurdueUniversity and a registered Professional Engineer in Indiana. His work experience includesseveral years in the hot mix asphalt industry, during which time he was responsible for theproduction of asphalt mixture designs, problem resolution, forensic pavement investiga-tion, and pavement design and analysis in a five-state region. He was also involved in nation-al research initiatives while working as a Senior Research Associate for the National Centerfor Asphalt Technology in Auburn, Alabama. While there he was Principal and/or Co-Principal Investigator on projects funded by various state departments of transportation,the National Asphalt Pavement Association Research and Education Foundation, theFederal Highway Administration, and the National Cooperative Highway ResearchProgram. Through this research he has participated in adapting Superpave techniques andspecifications to specialized hot mix asphalt mixtures, preparation of specialized hot mixasphalt construction guidelines, development of new test methods, and specification writ-ing. Subsequently, Dr. Haddock has worked as a research engineer for the Indiana Dept. ofTransportation and the Asphalt Institute, before joining the Purdue University faculty.

Eric E. Harm Deputy Director for Project ImplementationIllinois Department of Transportation

Mr. Harm holds a BS in civil engineering from the University of Illinois and an MS in civilengineering from the University of California, Berkeley. He is a registered professional engi-neer and has been with the Illinois DOT since 1980. Previous DOT positions includeEngineer of Materials and Physical Research, Bituminous Operations Engineer, andMaterials Investigations Engineer. He is a member of a number of TRB committees and taskgroups including the standing technical committee on the Conduct of Research. He is amember of the AASHTO Technical Subcommittee on Materials and the StandingCommittee on Research. He is also a member of the Association of Asphalt PavingTechnologists.

Paul J. Mack Consultant Schenectady, New York

Mr. Mack holds a bachelor’s degree in civil engineering from Manhattan College and is a reg-istered professional engineer. He is a recently retired 30-year veteran of the New York StateDepartment of Transportation (NYSDOT), where he held a variety of engineering posts inhighway and waterway design, construction, and operations. Most recently he directed theTechnical Services Division of the DOT. Mr. Mack was the national team leader for the AASH-TO Superpave Lead State Team. He was also a member of the AASHTO Subcommittee onMaterials and the NYSDOT state representative. In 1985, he was named Statewide Engineer ofthe Year.

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Charles R. Marek Principal Materials EngineerVulcan Materials Company

Dr. Marek hold a BS and Ph.D. in civil engineering from the University of Illinois. From1967-1972, he was a member of the civil engineering faculty at the same institution. Hejoined Vulcan in 1972 and was named to his current position in 1986. Dr. Marek is a mem-ber of the American Society of Civil Engineers, the Association of Asphalt Technologists,and ASTM. He has served on several SHRP committees, including the PavementPerformance Advisory Committee, and is a member of the TRB standing technicalCommittee on Mineral Aggregates.

John B. MetcalfProfessor of EngineeringLouisiana State University

Dr. Metcalf is the Freeport-McMoRan Professor of Engineering at the Louisiana StateUniversity (LSU). He holds a BS and Ph.D. in civil engineering from Leeds University(U.K.). He is a fellow of the Geological Society of London, the Institution of Civil Engineers(U.K.), and the Institution of Engineers (Australia). He is also a member of the AmericanSociety of Civil Engineers. From 1958 to 1992, Dr. Metcalf worked for the Transport andRoad Research Laboratory (U.K.), the National Research Council of Canada, theQueensland Main Roads Dept. (Australia), and the Australian Road Research Board, wherehe served as deputy director from 1975 to 1992. He joined the LSU faculty in 1992. Hismain areas of academic interest are technology transfer, low-cost roads, non-standard mate-rials, pavement design and quality control. He is the author of more than 120 technicalpapers. Dr. Metcalf has provided consulting services to the United Nations, the World Bank,government agencies, and branches of industry in various countries. He is currentlyengaged in research on accelerated pavement testing, asphalt quality control, maintenancemanagement, and recycled rubber in highway construction. Dr. Metcalf is a member of, andformerly chaired, the Permanent Association of Road Congresses Committee on Roads inDeveloping Regions. He is a member of a number of TRB standing technical committees.

Gale C. Page State Flexible Pavement Materials EngineerFlorida Department of Transportation

Mr. Page holds a BSCE from the University of Wisconsin-Madison and a master’s degree inengineering from the University of Wisconsin-Milwaukee. Mr. Page is a registered profes-sional engineer. He has been with the Florida DOT for 23 years and has also had 10 yearsof experience with the Wisconsin DOT. He is familiar with all aspects of highway designand construction, but his specialty is highway construction materials, especially asphalt andasphalt mixtures. He is broadly experienced in the introduction of new materials technol-ogy within highway agencies, including standards development, technology transfer anddeployment strategies. Mr. Page is a member of ASTM, the American Society of CivilEngineers, and past president of the Association of Asphalt Paving Technologists, theInternational Society of Asphalt Pavements, and the Asphalt Recycling and ReclaimingAssociation. He serves or has served on several TRB standing technical committees, chair-ing two, and on several NCHRP project panels. Mr. Page served as a member and vice-chairof the SHRP Asphalt Advisory Committee through 1993. He is the author of 15 refereedpapers and many technical reports.

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Douglas R. RoseDeputy Administrator, Chief EngineerMaryland State Highway Administration

Mr. Rose holds a BS in civil and environmental engineering from Clarkson College ofTechnology and an MS in civil engineering from the University of Maryland. Mr. Rose wasappointed Chief Engineer in 1995 and has more than 20 years of experience in highway con-struction, maintenance, and traffic operations. Mr. Rose is active on a number of AASHTOcommittees including the Technology Implementation Group and the Joint AssociatedGeneral Contractors-American Road and Transportation Builders Association-AASHTOTask Force. He serves on the Board of Directors of the Maryland Association of Engineersand is a member of the American Society of Civil Engineers, the American Society ofHighway Engineers, and the American Public Works Association.

Byron E. Ruth (Served through 2004)Professor of Civil Engineering, EmeritusUniversity of Florida

Dr. Ruth holds BS, MS, and Ph.D. degrees in civil engineering, respectively, from MontanaState University, Purdue University, and West Virginia University. Dr. Ruth is a registeredprofessional engineer. He has specialized in pavement design, highway materials, and soilmechanics. Dr. Ruth has authored or co-authored numerous publications on the perform-ance of asphalt pavements and paving materials. He is a life member of the AmericanSociety of Civil Engineers, ASTM (where he chaired the Committee on Road and PavingMaterials), a member of the Association of Asphalt Paving Technologists (past president),and serves on several TRB standing technical committees related to asphalt and asphaltpaving.

Dean C. Weitzel Chief Materials EngineerNevada Department of Transportation

As Chief Materials Engineer for the Nevada DOT, Mr. Weitzel is responsible for the admin-istration of a multimillion dollar activity devoted to highway materials selection and quali-ty assurance, development and application of specification, and the conduct of physicalresearch. Mr. Weitzel holds a bachelor of science degree in civil engineering from theUniversity of Nevada and is a registered professional engineer in the states of Nevada andCalifornia. Mr. Weitzel has a total of 20 years of experience in highway design and construc-tion. In addition to his experience in highway materials and research, Mr. Weitzel has expe-rience in bridge and roadway design.

J.T. Yarnell Chief EngineerMissouri Department of Transportation (retired)

Mr. Yarnell is a graduate of the University of Kansas (B.Sc., civil engineering). He was withthe Missouri Department of Transportation for 35 years, where he has held a series of pro-gressively important posts. This experience has provided a broad background in highwayengineering and operations. Mr. Yarnell was appointed Chief Engineer of the Departmentin 1998 and retired from the department in 2001. He is a registered professional engineerand a member of the American Society of Civil Engineers and the Missouri Society ofProfessional Engineers.

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