Feasibility of using 100% recycled asphalt pavement mixtures for road construction

ii To my family, friends and professors who helped me throughout this experience iii ACKNOWLEDGEMENTS This research project was made possible with the help of many supporting people throughout the process. I wish to express my gratitude firstly to my supervising professor, Dr. Hosin " David " Lee for the support and advice needed to start and finish this project. I would also like to thank the thesis committee for their assistance in the completion of this research and thesis. Also, I would like to acknowledge Dr. Chris Williams for allowing access to the Iowa State facilities, along with Paul Ledtje and Andy Cascione for their knowledge and expertise with the lab equipment. I would also like to acknowledge my colleagues, Taha Ahmed and Clint Van Winkle, in the graduate school that assisted with the project. Finally, I would the like to acknowledge The University of Iowa for providing access and facilities to make this research project possible. iv ABSTRACT Recycled Asphalt Pavement (RAP) is the largest recycled good in the United States and 80 million tons are recycled yearly, saving taxpayers about $1.5 billion dollars. This paper explores the possibility of utilizing 100% RAP materials in asphalt pavement. Asphalt mixtures are produced at 135°C in a typical asphalt plant. However, at 135°C, not all binder from RAP materials may not become effective for coating aggregates. The main objective of the study is to determine the amount of effective binder available from RAP in the asphalt plant. The 100% RAP mixes have aged binder that can alter mix designs and interaction with virgin binder. In this study, to determine low temperature cracking resistance and fatigue performance, samples were prepared using a 100% RAP mix with no virgin binder and a 100% RAP mix with virgin asphalt binder to achieve the optimum binder content of the mix. Second, to determine the effectiveness of binder from RAP materials, compaction tests were performed by heating RAP materials at various temperatures. It was found that 100% RAP mixes cannot be feasible for field use if additional virgin binder is added to reach the optimum asphalt content. Based on limited test results, the low temperature grade was not within proper limits but the beam fatigue testing results were acceptable. Based on compaction test results, additional heating is needed to increase the effectiveness of asphalt binder from RAP materials.