Using Existing Pavement in Place and Achieving Long Life (2014)

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5C h a p t e r 1 This report documents the findings from SHRP 2 Renewal Project R23, Using Existing Pavement in Place and Achieving Long Life. The SHRP 2 Renewal area focuses on improving the ability to design and construct long-lasting highway projects quickly with minimal disruption to the traveling public. Key components to achieving these objectives include the applica- tion of innovative methods and materials for preserving, reha- bilitating, and reconstructing the nation’s transportation infrastructure. Specific to the R23 project, construction costs and time can be greatly reduced if the existing pavement can be used in place as part of the rehabilitation solution. During the past 20 years, there have been numerous proj- ects where the existing pavement was either modified in place or used as is and a new structural pavement was placed on top. Both asphalt and concrete pavement solutions have shown promise, but there is limited in-service performance on heavy-duty pavements. Techniques include rubblizing and crack and seat technique for asphalt-over-concrete pave- ments and concrete-over-concrete or concrete-over-asphalt pavements. There is a need for reliable procedures that allow agencies to identify when an existing pavement can successfully be used in place and how to incorporate it into the new struc- tural pavement to achieve long life. The guidelines, resource documentation, specifications, manuals, and software devel- oped as part of the SHRP 2 R23 effort focused on addressing these needs. This effort concentrated on understanding the state of the art of rapid renewal approaches currently used both nation- ally and internationally to construct long-lived pavement for high-volume roadways. The project also identified promis- ing alternatives to renewal approaches currently in use (but without substantive performance history) or imminently on the horizon. SHRP 2 has defined long-life pavements as those lasting in service for 50 years or longer (details on the long-life definition can be found in subsequent sections of this report). State highway agency (SHA) participation and contribu- tion to this project were critical in developing a practical and useable set of guidelines and tools. The project team recog- nizes the critical and substantial information and feedback provided by the following agencies: • Illinois Tollway Authority (ITA); • Michigan Department of Transportation (MDOT); • Minnesota Department of Transportation (MnDOT); • Missouri Department of Transportation (MoDOT); • Texas Department of Transportation (TxDOT); • Virginia Department of Transportation (VDOT); and • Washington State Department of Transportation (WSDOT). project Objectives The goal of this project was to develop reliable procedures that identify when existing pavements can be used in place and the methods necessary to incorporate the original material into the new pavement structure while achieving long life. To that end, the project had the following objectives: • Identification of alternatives for using existing pavements in place for rapid renewal; • Analysis of advantages and disadvantages of each approach under different conditions; • Development of detailed criteria on when an existing pave- ment can be used in place, with or without significant modification; • Identification of practices and techniques available to con- struct pavements with the above characteristics; and • Determination of the optimal methods to integrate the renewed pavement with adjacent pavements and structures. Background

6Scope of Work Project R23 was structured in two phases. Phase 1 consisted of five tasks: 1. Document current renewal approaches in use by SHAs. 2. Analyze renewal approaches to determine which factors are critical for success. 3. Develop criteria for when existing pavement can be used, with or without modification. 4. Present advantages and disadvantages of each approach under different project conditions. 5. Develop an interim report and Phase 2 work plan. Phase 1 focused on documenting the existing practices, ana- lyzing each approach to determine which factors are critical for success, establishing criteria on when the existing structure requires modification (i.e., pulverization, rubblization, crack and seat) as part of the renewal, and evaluating the advantages or disadvantages of renewal approaches. These findings served as the basis for developing practical design guides in consulta- tion with seven SHAs during Phase 2. This was accomplished by working with the states to develop draft guidelines, using the guidelines on a test project in each state, and then facilitating two regional workshops with the agencies where agency per- sonnel, industry, and contractors were able to provide input on the process. The workshops were also used to compare designs between the existing agency practice and the new procedure developed from this study. Phase 2 consisted of the following tasks: 1. Work with seven SHAs to develop practical design guides. 2. Verify usability of design guides by designing actual proj- ects with each SHA. 3. Compare the results from new design guides and existing SHA procedures and solicit feedback through regional workshops. 4. Revise guidelines based on comments from SHAs. 5. Develop final report and final design guidelines. report Organization The research approach used for the study is described in Chap- ter 2. The methodology associated with the two major phases is described along with the agency interactions. A summary of the Phase 1 and Phase 2 activities performed for this study is provided in Chapter 3. Details on the national and international literature review and survey can be found in Appendix A. The analysis conducted using test sections from the Long-Term Pavement Performance program can be found in Appendix B. The development of the decision matrices for both flexible and rigid pavement renewal can be found in Appendix C. Appendix D shows how the flexible and rigid pavement renewal thickness design tables were developed. Chapter 3 provides an overview of the products developed from the project including the interactive software that directs the user through the guidelines and contains the pri- mary resource documentation. The following resource docu- mentation can also be found in this project’s guide: • Guide, Chapter 1—Project Assessment Manual; • Guide, Chapter 2—Flexible Pavement Best Practices; • Guide, Chapter 3—Rigid Pavement Best Practices; • Guide, Chapter 4—Guide Specifications; • Guide, Chapter 5—Life-Cycle Cost Analysis; and • Guide, Chapter 6—Emerging Pavement Technology. A summary including conclusions, implementation, and suggested additional research are provided in this report’s Chapter 4.