Technical Report Documentation Page 1. Report No. 2. Government Accession No. 3. Recipient’s Catalog No. FHWA/TX-03/4126–1 4. Title and Subtitle 5. Report Date USING INFRARED IMAGING AND GROUND-PENETRATING May 2002 RADAR TO DETECT SEGREGATION IN HOT-MIX OVERLAYS Resubmitted: September 2002 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. Stephen Sebesta and Tom Scullion Report 4126-1 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. 0-4126 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered Texas Department of Transportation Research: Research and Technology Implementation Office September 2000–April 2002 P. O. Box 5080 14. Sponsoring Agency Code Austin, Texas 78763-5080 15. Supplementary Notes Research performed in cooperation with the Texas Department of Transportation and the U.S. Department of Transportation. Research Project Title: Development of Infrared Photography and GPR Procedures for Identifying Mixture Segregation 16. Abstract Segregation of any type is a serious problem in hot-mix asphalt and typically leads to poor performance, poor durability, shorter life, and higher maintenance costs. This project focused on using both infrared (IR) imaging and ground-penetrating radar (GPR) to evaluate the uniformity of newly placed hot- mix overlays. Both techniques provide a distinct advantage over existing nuclear techniques in that they provide 100 percent coverage of the new surface. In this project IR and GPR measurements were made in test sections on four newly placed asphalt overlays. Cores were taken where anomalies were detected in the mat. These cores were returned to the laboratory to identify changes in both the volumetric and engineering properties. Analysis showed that significant changes in both IR and GPR values are related to changes in hot- mix properties, primarily air void content. Based upon current Texas Department of Transportation (TxDOT) specifications significant changes in the hot-mix asphalt are expected if temperature changes of greater than 25 °F are measured in the field. If the surface dielectric changes by more than 0.8 for coarse- graded mixes and 0.4 for dense-graded materials, significant changes in mix properties are expected. The approach used in Finland to use a calibration core to convert GPR surface dielectric to mat air void contents worked well. TxDOT should consider future implementation of these technologies. Neither of the devices used in this project was thought optimal for full implementation. The research team has provided schematics and recommendations for future implementation efforts. 17. Key Words 18. Distribution Statement Segregation, Infrared, Ground-Penetrating Radar, No restrictions. This document is available to the Paving, Quality Control, Quality Assurance public through NTIS: National Technical Information Service 5285 Port Royal Road Springfield, Virginia 22161 19. Security Classif.(of this report) 20. Security Classif.(of this page) 21. No. of Pages 22. Price Unclassified Unclassified 176 Form DOT F 1700.7 (8-72) Reproduction of completed page authorized USING INFRARED IMAGING AND GROUND-PENETRATING RADAR TO DETECT SEGREGATION IN HOT-MIX OVERLAYS by Stephen Sebesta Assistant Transportation Researcher Texas Transportation Institute and Tom Scullion Research Engineer Texas Transportation Institute Report 4126-1 Project Number 0-4126 Research Project Title: Development of Infrared Photography and GPR Procedures for Identifying Mixture Segregation Sponsored by the Texas Department of Transportation in cooperation with the U.S. Department of Transportation May 2002 Resubmitted: September 2002 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 Texas Department of Transportation (TxDOT) or the Federal Highway Administration (FHWA). This report does not constitute a standard, specification, or regulation. The engineer in charge was Tom Scullion, P.E. (Texas, # 62683). v ACKNOWLEDGMENTS This project was made possible by the Texas Department of Transportation in cooperation with the Federal Highway Administration. Numerous persons have made the accomplishment of this project possible. First, the personnel of the Texas Department of Transportation who have worked to facilitate project needs: Magdy Mikhail P.E., the project director, was instrumental in providing project oversight. The project also would not have been possible without the assistance of district personnel who assisted with coordinating test sections: • Catherine Hejl, P.E., Bryan District • Darlene Goehl, P.E, Bryan District • Zyna Polansky, Bryan District • P.J. Vargas, Bryan District • Darla Walton, Bryan District • Gerald Freytag, P.E., Yoakum District • James Ivy P.E., Yoakum District • Tony Yrigoyen, P.E., Houston District Gary Strahan of Texas Infrared provided technical guidance on the usage of the infrared products, and Rob Raymer of FLIR Systems provided a ThermaCam PM 695 for trial at one of the test sites. Field data collection would not have been possible without the assistance of Lee Gustavus, Pat Harris, and Spencer Guthrie of the Texas Transportation Institute (TTI) coming out and braving the summer heat. Sydney Greer assisted by providing guidance on the laboratory testing of the asphalt cores. vi TABLE OF CONTENTS Page List of Figures ............................................................................................................................... x List of Tables ............................................................................................................................. xiii Executive Summary ........................................................................................................................ 1 Chapter 1 Introduction ................................................................................................................... 3 I. Background ........................................................................................................................ 3 II. Objectives ........................................................................................................................... 3 III. Work Plan .......................................................................................................................... 4 Chapter 2 Literature Review .......................................................................................................... 5 I. Summary ......................................................................................................................... 5 II. Kansas Department of Transportation (KDOT)............................................................... 5 III. Texas Department of Transportation (TxDOT) .............................................................. 7 IV. Connecticut Department of Transportation (CDOT)....................................................... 8 V. Washington Department of Transportation (WSDOT)................................................... 8 VI. National Center for Asphalt Technology (NCAT) ......................................................... 11 VII. Michigan Department of Transportation (MDOT) ....................................................... 14 VIII. Infrared Imaging ............................................................................................................ 15 IX. Ground-Penetrating Radar ............................................................................................ 18 Chapter 3 Laboratory Verification of Infrared Equipment .......................................................... 23 I. Summary ........................................................................................................................ 23 II. Emissivity Determination of Hot Plate Surface ............................................................... 24 III. Laboratory Verification of Infrared Camera Temperatures under Windless Conditions ....................................................................................................... 26 IV. Laboratory Investigation of Wind Effects on Infrared-Determined Temperatures ......... 31 V. Implications for Field Testing ......................................................................................... 34 Chapter 4 Field Data Collection and Analysis Procedures .......................................................... 37 I. Protocol Development ..................................................................................................... 37 II. Field Testing Protocol for Data Collection ....................................................................... 37 Chapter 5 SH 6 Investigation ....................................................................................................... 41 vii I. Summary ......................................................................................................................... 41 II. Paving Parameters and Environmental Conditions ........................................................ 42 III. Infrared Imaging Settings............................................................................................... 42 IV.