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2017 N A T I O N A L C O O P E R A T I V E H I G H W A Y R E S E A R C H P R O G R A M NCHRP RESEARCH REPORT 847 Variability of Ignition Furnace Correction Factors Carolina Rodezno NatioNal CeNter for asphalt teChNology auburN uNiversity Auburn, AL Ray Brown NatioNal CeNter for asphalt teChNology auburN uNiversity Auburn, AL Grant Julian NatioNal CeNter for asphalt teChNology auburN uNiversity Auburn, AL Brian Prowell advaNCed Materials serviCes Auburn, AL Subscriber Categories Materials Research sponsored by the American Association of State Highway and Transportation Officials in cooperation with the Federal Highway Administration
NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed research is the most effective way to solve many problems facing highway administrators and engineers. Often, highway problems are of local interest and can best be studied by highway departments individually or in cooperation with their state universities and others. However, the accelerating growth of highway transportation results in increasingly complex problems of wide inter- est to highway authorities. These problems are best studied through a coordinated program of cooperative research. Recognizing this need, the leadership of the American Association of State Highway and Transportation Officials (AASHTO) in 1962 ini- tiated an objective national highway research program using modern scientific techniquesâthe National Cooperative Highway Research Program (NCHRP). NCHRP is supported on a continuing basis by funds from participating member states of AASHTO and receives the full cooperation and support of the Federal Highway Administration, United States Department of Transportation. The Transportation Research Board (TRB) of the National Academies of Sciences, Engineering, and Medicine was requested by AASHTO to administer the research program because of TRBâs recognized objectivity and understanding of modern research practices. TRB is uniquely suited for this purpose for many reasons: TRB maintains an extensive com- mittee structure from which authorities on any highway transportation subject may be drawn; TRB possesses avenues of communications and cooperation with federal, state, and local governmental agencies, univer- sities, and industry; TRBâs relationship to the Academies is an insurance of objectivity; and TRB maintains a full-time staff of specialists in high- way transportation matters to bring the findings of research directly to those in a position to use them. The program is developed on the basis of research needs identified by chief administrators and other staff of the highway and transporta- tion departments and by committees of AASHTO. Topics of the highest merit are selected by the AASHTO Standing Committee on Research (SCOR), and each year SCORâs recommendations are proposed to the AASHTO Board of Directors and the Academies. Research projects to address these topics are defined by NCHRP, and qualified research agencies are selected from submitted proposals. Administration and surveillance of research contracts are the responsibilities of the Acad- emies and TRB. The needs for highway research are many, and NCHRP can make significant contributions to solving highway transportation problems of mutual concern to many responsible groups. The program, however, is intended to complement, rather than to substitute for or duplicate, other highway research programs. Published research reports of the NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM are available from Transportation Research Board Business Office 500 Fifth Street, NW Washington, DC 20001 and can be ordered through the Internet by going to http://www.national-academies.org and then searching for TRB Printed in the United States of America NCHRP RESEARCH REPORT 847 Project 09-56 ISSN 2572-3766 (Print) ISSN 2572-3774 (Online) ISBN 978-0-309-44637-2 Library of Congress Control Number 2017939359 Â© 2017 National Academy of Sciences. All rights reserved. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FRA, FTA, Office of the Assistant Secretary for Research and Technology, PHMSA, or TDC endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. NOTICE The research report was reviewed by the technical panel and accepted for publication according to procedures established and overseen by the Transportation Research Board and approved by the National Academies of Sciences, Engineering, and Medicine. The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research and are not necessarily those of the Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; or the program sponsors. The Transportation Research Board; the National Academies of Sciences, Engineering, and Medicine; and the sponsors of the National Cooperative Highway Research Program do not endorse products or manufacturers. Trade or manufacturersâ names appear herein solely because they are considered essential to the object of the report.
The National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, non- governmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Marcia McNutt is president. The National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. C. D. Mote, Jr., is president. The National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president. The three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. The Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine. Learn more about the National Academies of Sciences, Engineering, and Medicine at www.national-academies.org. The Transportation Research Board is one of seven major programs of the National Academies of Sciences, Engineering, and Medicine. The mission of the Transportation Research Board is to increase the benefits that transportation contributes to society by providing leadership in transportation innovation and progress through research and information exchange, conducted within a setting that is objective, interdisciplinary, and multimodal. The Boardâs varied committees, task forces, and panels annually engage about 7,000 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. The program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individuals interested in the development of transportation. Learn more about the Transportation Research Board at www.TRB.org.
C O O P E R A T I V E R E S E A R C H P R O G R A M S CRP STAFF FOR NCHRP RESEARCH REPORT 847 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs Edward T. Harrigan, Senior Program Officer Anthony P. Avery, Senior Program Assistant Eileen P. Delaney, Director of Publications Doug English, Editor NCHRP PROjECT 09-56 PANEL Field of Materials and ConstructionâArea of Bituminous Materials Kim A. Willoughby, Washington State DOT, Olympia, WA (Chair) Timothy L. Ramirez, Pennsylvania DOT, Harrisburg, PA Mark J. Brum, Massachusetts DOT, Boston, MA Michael S. Buchanan, Oldcastle Materials Company, Birmingham, AL Nathan D. Maack, Michigan DOT, Lansing, MI Charles W. Paugh, Engineering & Software Consultants, Inc., Chantilly, VA Gregory A. Sholar, Florida DOT, Gainesville, FL Brett Stanton, Superior Bowen, Kansas City, MO Dean C. Weitzel, Carson City, NV Matthew Corrigan, FHWA Liaison
F O R E W O R D This report presents a proposed practice in AASHTO standard format for installa- tion, operation, and maintenance of ignition furnaces. The report will be of immediate inter- est to materials engineers in state highway agencies and the asphalt pavement construction industry. AASHTO T 308, âDetermining the Asphalt Binder Content of Hot Mix Asphalt (HMA) by the Ignition Method,â requires determination of asphalt and aggregate correction factors for asphalt mix designs for each ignition furnace used to test a design. In some cases, where there are numerous asphalt mix designs or numerous ignition furnaces testing a particular mix design, correction factors may be shared between ignition furnaces, though this practice is not strictly permitted by AASHTO T 308 without supporting evidence. There is a lack of knowledge of (1) how ignition furnace installation, operation, and mainte- nance influence correction factors; (2) consequences of sharing correction factors between units/ mixes; and (3) ways to minimize differences that arise between ignition furnaces. Moreover, there is a lack of a statistically valid verification procedure to identify causes for non-comparing, statistically different, or biased test results from ignition furnaces. A verification procedure may promote consistency in test results and assist in dispute resolution. The objectives of this research were to (1) determine the significant influences that affect the variability of asphalt and aggregate correction factors for ignition furnaces; (2) develop guidelines for the installation, operation, and maintenance of ignition furnaces to minimize the variability in correction factors between furnaces; and (3) develop and document a statis- tically valid correction factor verification procedure to identify and troubleshoot causes for non-comparing, statistically different, or biased results of AASHTO T 308. The research was performed by the National Center for Asphalt Technology (NCAT), Auburn, Alabama, with the support of Advanced Materials Services, LLC, Auburn, Alabama. The research was conducted in three parts: (1) a study of the sensitivity of asphalt and aggregate correction factors to variation in experimental factors such as furnace type, test temperature, asphalt content, and sample mass; (2) a round-robin study to identify cor- rection factor outliers and determine the contributory cause(s); and (3) troubleshooting by NCAT of outliers from the round-robin study. The research found that the primary factors affecting asphalt and aggregate correction factors determined by AASHTO T 308 are furnace type and test temperature. Conducting the test at 800Â°F appears to substantially reduce the magnitude and standard deviation of the correction factors for asphalt mixtures that do not contain lime. Sharing correc- tion factors among different ignition furnaces appears acceptable for low correction factor aggregates (0.1% or less) but is problematic for aggregates with correction factors of 1.0% By Edward T. Harrigan Staff Officer Transportation Research Board
or greater. The current precision estimates in AASHTO T 308 appear applicable only to mixtures with low correction factor aggregates. The key product of this research is a Proposed Standard Practice for Installation, Opera- tion, and Maintenance of Ignition Furnaces (Appendix I). The NCHRP project panel, after careful review of the experimental results with the research team, concluded that develop- ment of a verification procedure to identify causes for non-comparing, statistically differ- ent, or biased test results from ignition furnaces was premature. Further research is planned to conduct an interlaboratory study of AASHTO T 308 in accordance with ASTM E691 as a basis for development of a robust, definitive verification procedure. This research will also address the effect of reclaimed asphalt pavement and recycled asphalt shingle content on determination of asphalt mixture correction factors. This report fully documents the research and includes nine appendixes: Appendix A: State DOT and Contractor Survey Appendix B: Summary of State Test Methods Compared with AASHTO T 308 Appendix C: Sensitivity Experiment Matrices and Asphalt Content Test Results Appendix D: Instructions to Round-Robin Participants and Data Report Appendix E: Round-Robin Test Results Appendix F: Round-Robin Test Results Analyses Tables per ASTM E691 Appendix G: Checklist for Troubleshooting Laboratory Visits Appendix H: Comparison of Burning Profiles for Laboratory 23 Appendix I: Proposed Standard Practice for Installation, Operation, and Maintenance of Ignition Furnaces with Commentary
C O N T E N T S 1 Chapter 1 Introduction 1 1.1 Objective 1 1.2 Scope 2 Chapter 2 Literature Review 2 2.1 Background 4 2.2 Types of Ignition Furnaces 5 2.3 Ignition Furnace Studies 16 2.4 RAP and RAS Asphalt Content Determination Using Ignition Furnace 17 2.5 Summary of Findings from the Literature Review 18 Chapter 3 Survey of State DOT and Industry Practice Regarding the Use of Ignition Furnaces 18 3.1 Introduction 25 3.2 Summary of Survey of State DOT and Industry Practice 27 Chapter 4 Experimental Plan Description 27 4.1 Sensitivity Study at the NCAT Lab 31 4.2 Round-Robin Study at Various Labs 33 4.3 Troubleshooting Correction Factors That Differ Significantly from Other Correction Factors in Round-Robin Study 34 Chapter 5 Results and Analysis of the Experiments 34 5.1 Sensitivity Experiments 48 5.2 Round-Robin Study 58 5.3 Troubleshooting Outliers from Round-Robin Study 65 Chapter 6 Summary of Findings 65 6.1 Sensitivity Study at NCAT Lab 66 6.2 Round-Robin Study 69 Chapter 7 Conclusions and Recommendations 70 References A-1 Appendix A State DOT and Contractor Survey B-1 Appendix B Summary of State Test Methods Compared with AASHTO T 308 C-1 Appendix C Sensitivity Experiment Matrices and Asphalt Content Test Results D-1 Appendix D Instructions to Round-Robin Participants and Data Report
E-1 Appendix E Round-Robin Test Results F-1 Appendix F Round-Robin Test Results Analyses Tables per ASTM E691 G-1 Appendix G Checklist for Troubleshooting Laboratory Visits H-1 Appendix H Comparison of Burning Profiles for Laboratory 23 I-1 Appendix I Proposed Standard Practice for Installation, Operation, and Maintenance of Ignition Furnaces with Commentary