Performance of Reclaimed Asphalt Pavement on Unpaved Roads Scott Koch George Huntington, P.E. Khaled Ksaibati, PhD., P.E. Wyoming Technology Transfer Center University of Wyoming Laramie, Wyoming May 2013 Acknowledgments The authors would like to thank all the employees of Laramie, Johnson and Sweetwater counties who assisted with this project. Without their expertise, assistance, and cooperation, this study could not have been conducted. Thanks to the Desert Mountain Corporation for their expertise and assistance on the Sweetwater County sections. We would also like to thank the Wyoming Department of Transportation for their support of this project. Finally, we would like to thank Mary Harman, Bart Evans, Josh Jones, Burt Andreen, Jonathan Zumwalt, and Harry Rocheville for their work on this project. Disclaimer The contents of this report reflect the work of the authors, who are responsible for the facts and the accuracy of the information presented. Mention of specific products is for informational purposes only and does not constitute any endorsement. This document does not constitute any policy of or endorsement by the Mountain-Plains Consortium or the University of Wyoming.This document is disseminated under the sponsorship of the Mountain-Plains Consortium in the interest of information exchange. The U.S. Government assumes no liability for the contents or use thereof. North Dakota State University does not discriminate on the basis of age, color, disability, gender expression/identity, genetic information, marital status, national origin, public assistance status, sex, sexual orientation, status as a U.S. veteran., race or religion. Direct inquiries to the Vice President for Equity, Diversity and Global Outreach, 205 Old Main, (701) 231-7708. TABLE OF CONTENTS 1. Introduction ........................................................................................................................... 1 1.1 Background ...................................................................................................................... 1 1.2 Problem Statement ........................................................................................................... 1 1.3 Research Objectives ......................................................................................................... 2 1.4 Report Organization ......................................................................................................... 3 2. Literature Review ................................................................................................................. 5 2.1 Asphalt Pavement Reclamation and Recycling ............................................................... 5 2.2 Obtaining Reclaimed Asphalt Pavement.......................................................................... 6 2.3 Uses of Reclaimed Asphalt Pavement ............................................................................. 6 2.3.1 In-Place Recycling .................................................................................................... 7 2.3.2 Hot Mix Asphalt and Reclaimed Asphalt Pavement (RAP) ..................................... 8 2.3.3 Cold Mix Asphalt (Central Processing Facility) ....................................................... 8 2.3.4 Full Depth Reclamation ............................................................................................ 8 2.3.5 Embankment or Fill .................................................................................................. 8 2.3.6 Mechanically Stabilized Earth Walls ........................................................................ 9 2.4 Economics of Reclaimed Asphalt Pavement (RAP) ........................................................ 9 2.4.1 RAP in Hot Mix Asphalt........................................................................................... 9 2.4.2 RAP in Road Base .................................................................................................. 12 2.5 Unpaved Roads .............................................................................................................. 12 2.5.1 Gravel Road Distresses ........................................................................................... 13 2.5.2 Dust Control ............................................................................................................ 16 2.5.3 Dust Collection and Measurement .......................................................................... 19 2.6 Literature Review Summary .......................................................................................... 20 3. Methodology ........................................................................................................................ 21 3.1 Test Section Descriptions ............................................................................................... 21 3.1.1 Site Layouts ............................................................................................................ 23 3.1.2 Traffic ..................................................................................................................... 25 3.1.3 Surfacing Materials: Aggregate, RAP and Cement-Treated Base (CTB) ............. 25 3.1.4 Dust Suppression Agents ........................................................................................ 33 3.2 Testing Methods ............................................................................................................. 34 3.2.1 Aggregate ................................................................................................................ 34 3.2.2 Weather ................................................................................................................... 34 3.2.3 Dust Assessment ..................................................................................................... 34 3.2.4 Roadway Condition Evaluations: URCI ................................................................ 37 3.3 Construction Methods .................................................................................................... 37 3.3.1 Laramie County: Blade Mixed............................................................................... 37 3.3.2 Johnson County: Stockpile Mixed ......................................................................... 40 3.3.3 Sweetwater County: Reclaimer Mixed .................................................................. 45 3.4 Summary of Methodologies ........................................................................................... 52 4. Results .................................................................................................................................. 53 4.1 Visual Dust Ratings vs Dustometer Measurements ....................................................... 53 4.2 Environmental Effects on Dust Measurements .............................................................. 56 4.2.1 Dust vs Age ............................................................................................................. 56 4.2.2 Dust vs Moisture Content ....................................................................................... 57 4.2.3 Dust vs Wind Speed ................................................................................................ 57 4.3 Laramie County .............................................................................................................. 60 4.3.1 Materials Properties ................................................................................................ 60 4.3.2 Visual Observations ................................................................................................ 64 4.3.3 Unsurfaced Road Condition Index (URCI) ............................................................ 68 4.3.4 Dust Emissions........................................................................................................ 69 4.4 Johnson County .............................................................................................................. 72 4.4.1 Materials Properties ................................................................................................ 72 4.4.2 Visual Observations ................................................................................................ 74 4.4.3 Unsurfaced Road Condition Index.......................................................................... 77 4.4.4 Dust Emissions........................................................................................................ 77 4.5 Sweetwater County ........................................................................................................ 78 4.5.1 Materials Properties ................................................................................................ 78 4.5.2 Visual Observations ................................................................................................ 81 4.5.3 Unsurfaced Road Condition Index.......................................................................... 94 4.5.4 Dust Emissions........................................................................................................ 98 4.6 Summary of Results ..................................................................................................... 100 5. Economic Analyses............................................................................................................ 103 5.1 Study Section: Sweetwater County Road 23: Crooks Gap Road ...............................