Technical Report Documentation Page 1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. FHWA/TX-03/0-4358-1 4. Title and Subtitle 5. Report Date MATERIALS, SPECIFICATIONS, AND CONSTRUCTION October 2002 TECHNIQUES FOR HEAVY-DUTY FLEXIBLE BASES: Resubmitted: July 2005 LITERATURE REVIEW AND STATUS REPORT ON 6. Performing Organization Code EXPERIMENTAL SECTIONS 7. Author(s) 8. Performing Organization Report No. Arno Hefer and Tom Scullion Report 0-4358-1 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) Texas Transportation Institute The Texas A&M University System 11. Contract or Grant No. College Station, Texas 77843-3135 Project No. 0-4358 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered Texas Department of Transportation Technical Research: Research and Technology Implementation Office September 2001 – August 2002 P. O. Box 5080 14. Sponsoring Agency Code Austin, Texas 78763-5080 15. Supplementary Notes Project performed in cooperation with the Texas Department of Transportation and the Federal Highway Administration. Project Title: Materials, Specifications, and Construction Techniques for Heavy-Duty Flexible Bases URL: http://tti.tamu.edu/documents/0-4358-1.pdf 16. Abstract For the majority of the Texas highways the granular base layer is the main structural component of the pavement system. Project 0-4358 was initiated to provide TxDOT guidelines to improve its base specifications in order to better withstand the demands of future traffic loads. This report provides the results of a literature search and a survey of the performance of experimental heavy-duty base pavements recently constructed in Texas. Base specifications and construction practices from eight U.S. DOTs and two overseas countries were compared with TxDOT current and proposed specifications. Currently, TxDOT is the only agency that does not control the amount of fines (minus 200 fraction) in its bases. Research studies have indicated that high levels of minus 200 can severely impact both moisture susceptibility and cold weather performance. The newly proposed TxDOT specifications with limits on the fines content are in line with the practices of other agencies in similar climates. The results from three experimental sections on US-281, US-77 and FM-1810 provide several important observations about current base performance. The use of small amounts of stabilizer to upgrade marginal materials does not always guarantee a top-quality base. Better methods of selecting optimal stabilizer content are needed. Furthermore, the flexible bases with high fines content appear to have high initial field stiffnesses that decease rapidly with time. 17. Key Words 18. Distribution Statement Flexible Base, Heavy-Duty Base, Specifications, No restrictions. This document is available to the Performance public through NTIS: National Technical Information Service Springfield, Virginia 22161 http://www.ntis.gov 19. Security Classif.(of this report) 20. Security Classif.(of this page) 21. No. of Pages 22. Price Unclassified Unclassified 154 Form DOT F 1700.7 (8-72) Reproduction of completed page authorized MATERIALS, SPECIFICATIONS, AND CONSTRUCTION TECHNIQUES FOR HEAVY-DUTY FLEXIBLE BASES: LITERATURE REVIEW AND STATUS REPORT ON EXPERIMENTAL SECTIONS by Arno Hefer Graduate Research Assistant Texas Transportation Institute and Tom Scullion, P.E. Research Engineer Texas Transportation Institute Report 0-4358-1 Project Number 0-4358 Project Title: Materials, Specifications, and Construction Techniques for Heavy-Duty Flexible Bases Performed in cooperation with the Texas Department of Transportation and the Federal Highway Administration October 2002 Resubmitted: July 2005 TEXAS TRANSPORTATION INSTITUTE The Texas A&M University System College Station, Texas 77843-3135 DISCLAIMER The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official view or policies of the Federal Highway Administration (FHWA) or the Texas Department of Transportation (TxDOT). This report does not constitute a standard, specification, or regulation. The engineer in charge was Tom Scullion, P.E., (TX, # 62683). There was no invention or discovery conceived or first actually reduced to practice in the course of or under this contract, including any art, method, process, machine, manufacture, design or composition of matter, or any new useful improvement thereof, or any variety of plant, which is or may be patentable under the patent laws of the United States of America or any foreign country. v ACKNOWLEDGMENTS This project has been funded by TxDOT’s pavement and materials research management committee (RMC 1) and FHWA. Caroline Herrera is the project director for this project, and her guidance and direction are greatly appreciated. The staff of several Districts assisted with the field data collection; special thanks to Richard Williammee and Andrew Wimsatt from Fort Worth, Danny Gonzalez and Jeremy Hinojosa from Corpus Christi, and Rene Castro from the Pharr District. vi TABLE OF CONTENTS Page List of Figures................................................................................................................................ ix List of Tables ...................................................................................................................................x Chapter 1 Introduction and Background ........................................................................................1 Chapter 2 Current Performance-Related Specifications for High-Quality Granular Bases ..........5 2.1 Introduction .......................................................................................................................5 2.2 Comparison of Specifications Used by Different Road Agencies ....................................7 2.3 Strength of the Aggregate Mass ......................................................................................10 2.4 Gradation...........................................................................................................................13 2.5 Plasticity of the Fines.......................................................................................................18 2.6 Degradation and Soundness.............................................................................................21 2.7 Moisture Susceptibility ....................................................................................................23 2.8 Shape, Angularity, and Surface Texture..........................................................................26 2.9 Compaction......................................................................................................................27 2.10 Stiffness............................................................................................................................29 2.11 Summary..........................................................................................................................32 Chapter 3 Research Findings from the Recent NCHRP Study.....................................................33 3.1 Introduction ......................................................................................................................33 3.2 Selection of Candidate Test Methods ...............................................................................34 3.3 Development and Validation of an Aggregate Performance Prediction Procedure.........................................................................................................35 3.4 Future Research Suggested by the NCHRP Study ...........................................................39 3.5 Summary...........................................................................................................................39 Chapter 4 Aspects of Material and Construction Quality Control................................................41 4.1 Introduction.......................................................................................................................41 4.2 Construction Process Specifications.................................................................................42 4.3 Layer Thickness of Single Lifts........................................................................................43 4.4 Compaction.......................................................................................................................43 4.5 Surface Preparation and Finish .........................................................................................44 vii 4.6 Priming and Maintaining ..................................................................................................45 4.7 Compliance Testing ..........................................................................................................45 4.8 Summary............................................................................................................................46 Chapter 5 Performance Monitoring of Experimental Test Sections Constructed as Heavy-Duty Flexible Pavements..........................................................................................47 5.1 Introduction......................................................................................................................47 5.2 US-281 Test Sections in the Pharr District......................................................................48 5.3 US-77 Test Sections in the