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2021 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 961 Entrained Air-Void Systems for Durable Highway Concrete Peter Taylor Seyedhamed Sadati Kejin Wang Yifeng Ling Xin Wang Wen Sun Iowa State UnIverSIty Ames, IA John T. Kevern Siamak Ryazi UnIverSIty of MISSoUrI Kansas City, MO Subscriber Categories Construction â¢ Materials â¢ Pavements 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, and implementable research is the most effective way to solve many problems facing state departments of transportation (DOTs) administrators and engineers. Often, highway problems are of local or regional interest and can best be studied by state DOTs individually or in cooperation with their state universities and others. However, the accelerating growth of highway transporta- tion results in increasingly complex problems of wide interest to high- way 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 (FHWA), United States Department of Transportation, under Agree- ment No. 693JJ31950003. 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 National Academies is an insurance of objectivity; and TRB maintains a full-time staff of special- ists in highway 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 iden- tified by chief administrators and other staff of the highway and transportation departments, by committees of AASHTO, and by the FHWA. Topics of the highest merit are selected by the AASHTO Special Committee on Research and Innovation (R&I), and each year R&Iâs recommendations are proposed to the AASHTO Board of Direc- tors and the National 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 National Academies 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 https://www.nationalacademies.org and then searching for TRB Printed in the United States of America NCHRP RESEARCH REPORT 961 Project 18-17 ISSN 2572-3766 (Print) ISSN 2572-3774 (Online) ISBN 978-0-309-67372-3 Library of Congress Control Number 2020952523 Â© 2021 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, FTA, GHSA, NHTSA, 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; the FHWA; 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. John L. Anderson 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 National 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.nationalacademies.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 provide leadership in transportation improvements and innovation through trusted, timely, impartial, and evidence-based information exchange, research, and advice regarding all modes of transportation. The Boardâs varied activities annually engage about 8,000 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 AUTHOR ACKNOWLEDGMENTS The authors would like to acknowledge the many individuals and organizations that made this research project possible. Input was provided by individuals from several state departments of transportation (DOTs) and other agencies, including Michigan, Minnesota, Missouri, Nevada, New York State, Ohio, Pennsylvania, and South Dakota DOTs; the Minnesota MnROAD Research Facility; the Manitoba Infrastructure Department; and the Ontario Ministry of Transportation. The support provided by the staff at Iowa State Universityâs Portland Cement Concrete Pavement and Materials Research Laboratory is greatly appreciated; in particular, the assistance of Robert Steffes and Paul McIntyre. Support during the course of this work from Sharon Prochnow and Denise Wagner at the National Concrete Pavement Technology Center and from Sue Stokke, Pete Hunsinger, Alicia Hoermann, and Monica Richards at our Publications group is also sincerely appreciated. The authors also would like to extend their gratitude for assistance with equipment operation from Tyler Ley at Oklahoma State University and Lawrence Sutter at Michigan Technological University. Technical discussions and support provided by Travis Fields, Pat OâBannon, and Andrew Yoakum at the University of Missouri-Kansas City are also greatly appreciated. And the support provided by the Ash Grove Cement Company in Kansas City, Missouri, is gratefully acknowledged. CRP STAFF FOR NCHRP RESEARCH REPORT 961 Christopher J. Hedges, Director, Cooperative Research Programs Lori L. Sundstrom, Deputy Director, Cooperative Research Programs Amir N. Hanna, Senior Program Officer Eileen P. Delaney, Director of Publications Natalie Barnes, Associate Director of Publications NCHRP PROJECT 18-17 PANEL Field of Materials and ConstructionâArea of Concrete Materials Donald J. Janssen, University of Washington (Emeritus), Seattle, WA (Chair) Mick S. Syslo, Nebraska Department of Transportation, Lincoln, NE Darin Hodges, South Dakota Department of Transportation, Pierre, SD Paul D. Krauss, Wiss, Janney, Elstner Associates, Inc., Northbrook, IL James M. Krstulovich, Jr., Illinois Department of Transportation, Springfield, IL Patricia I. Baer, Pennsylvania Department of Transportation, Harrisburg, PA Tyson D. Rupnow, Louisiana Department of Transportation and Development, Baton Rouge, LA Kenny Seward, Oklahoma Department of Transportation, Oklahoma City, OK Ahmad A. Ardani, FHWA Liaison
This report presents recommended requirements for the air-void system parameters of concrete used in highway pavements and structures and proposed modifications to the current AASHTO test methods for evaluating concrete resistance to freezing and thawing. Implementing these recommendations will facilitate the evaluation of durability of con- crete mixtures used in highway pavements and structures as well the selection of concrete mixtures with sufficient resistance to freezeâthaw damage. The information contained in the report will guide materials engineers in evaluating, selecting, and specifying concrete mixtures that will provide the air-void characteristics and freezeâthaw resistance needed for enhanced durability, thus ensuring longevity of highway pavements and structures. The information contained in the report will be of immediate interest to state materials and construction engineers and others involved in specifying and evaluating concrete mixtures for use in highway pavements and structures. Laboratory testing and long-term field experience have shown that highway concrete must be properly air-entrained if it is to resist the action of freezing and thawing, particu- larly in wet climates. Experience has also shown that the effectiveness of air entrainment in providing resistance to freezing and thawing depends on the characteristics of the air-void system. These characteristics are influenced by the materials used in producing concrete; the practices for proportioning, mixing, and placing concrete; and field conditions. Laboratory methods are currently available for characterizing the air-void system in hardened concrete and for evaluating the freezeâthaw resistance of concrete. However, the parameters associated with this characterization and the results of these laboratory tests do not always reflect the observed field performance, nor do they consider the possible effects on other concrete properties. There was a need to identify the characteristics of the air-void system that relate to field performance and to enhance the criteria and methods used for evaluating the freezeâthaw resistance of highway concrete in order to achieve results reflecting field performance. Under NCHRP Project 18-17, âEntrained Air-Void System for Durable Highway Concrete,â Iowa State University was charged with identifying the characteristics of the entrained air-void system required for freezeâthaw durability of highway concrete and recommending improvements to the test methods used for measuring these characteristics and the methods used for evaluating freezeâthaw durability. To accomplish these objec- tives, the researchers reviewed and evaluated the current practices for characterizing the air-void system of highway concrete and the test methods available for evaluating freezeâthaw durability, and they conducted an experimental investigation of concrete samples produced in the laboratory or extracted from in-service projects. Based on the F O R E W O R D By Amir N. Hanna Staff Officer Transportation Research Board
findings of this work, the researchers then proposed minimum requirements for air-void parameters and modifications to the current AASHTO test methods for evaluating concrete resistance to freezing and thawing. This report summarizes the work performed on the project and includes seven appendices, not printed herein, that provide further details on the different aspects of the research. The appendices are available online at www.trb.org by searching for âNCHRP Research Report 961â. Appendix A: Test Matrix for Laboratory Mixtures Appendix B: Petrographic Analysis Report Appendix C: Data Obtained from Testing Concrete Mixtures Produced in the Laboratory Appendix D: Flatbed Scanner Threshold Optimization Details and Test Results Appendix E: Clustering Analysis Test Results Appendix F: Microcomputer Control for AASHTO T 161 âAâ F-T Cabinet Appendix G: Data Obtained During F-T Testing
1 Chapter 1 Introduction 1 Problem Statement 2 Research Objectives 2 Report Organization 3 Chapter 2 Background 3 FreezeâThaw Durability of Highway Concrete 3 Mixture Ingredients 4 Paste Porosity 5 Air-Void System 7 Mechanisms of FreezeâThaw Action on Hardened Concrete 8 Effects of Air Voids on Mechanical Properties 8 Measurement 8 Air-Void Systems 9 FreezeâThaw 10 Scaling 11 Chapter 3 Experimental Program 11 Research Scope and Approach 11 Laboratory Evaluations 11 Materials 13 Test Matrix 15 Test Procedures and Sample Preparation 23 Field Investigations 23 Selection of Field Investigation Sites 27 Field Investigation of Air-Void System Characteristics 33 Summary of Findings from Field Analyses 40 Laboratory Investigation 41 Measurement in the Fresh State 45 Measurement of Hardened Concrete 50 Clustering of Air Voids 52 Correlations Between Laboratory and Field Data 53 Summary 54 Test Methods for Evaluating FreezeâThaw Durability 55 FreezeâThaw Test Mixtures and Methods 56 Results 57 CDF-C: Brine Pretreatment 59 Summary and Conclusions from FreezeâThaw Testing C O N T E N T S
63 Chapter 4 Guidance on Protocols for Testing and Analysis 63 Protocols for Testing and Analysis 63 Air Content 63 Observations for Air-Void System Testing Using the SAM 64 Observation for Air-Void System Testing Using the Flatbed Scanner 64 Observations and Recommendations Based on Clustering 64 Observation and Recommendation for Improvements in Testing for FreezeâThaw Durability 64 Identification of Issues Affecting Implementation 66 Chapter 5 Summary and Recommendations for Research 66 Conclusions 67 Recommendations for Future Research 68 References 72 Appendices A-G Note: Photographs, figures, and tables in this report may have been converted from color to grayscale for printing. The electronic version of the report (posted on the web at www.trb.org) retains the color versions.