UC Davis Institute of Transportation Studies

This report summarizes a series of eight first-level Heavy Vehicle Simulator testing reports, two laboratory reports on shear and fatigue testing, a forensic investigation report, a report on the backcalculation of deflection measurements, and a second-level analysis report, all of which document an investigation undertaken to validate Caltrans overlay strategies for the rehabilitation of cracked asphalt concrete using modified binder overlays. The work was conducted by the University of California Pavement Research Center (UCPRC) as part of Partnered Pavement Research Center Strategic Plan Element 4.10: “Development of Improved Rehabilitation Designs for Reflective Cracking.” This work was originally requested by the Caltrans/Industry Rubber Asphalt Concrete Task Group (RACTG) to compare the performance of one set of examples of thin overlays of cracked asphalt pavement containing different types of binders modified with recycled tire rubber. This work, included as Appendix H of the Rubber Modified Binder Pilot Projects Review prepared by the RACTG, is part of a more comprehensive work plan prepared by the Task Group that included evaluation of pilot projects and construction and monitoring of field test sections (undertaken by Caltrans). The objective of this UCPRC project was met after completion of the following four tasks: 1. Develop improved mechanistic models of reflective cracking in California, 2. Calibrate and verify these models using laboratory and HVS testing, 3. Evaluate the most effective strategies for reflective cracking, and 4. Provide recommendations for reflective cracking strategies. This report addresses all the tasks and consists of six main chapters. Chapter 2 lists the objectives and project organization. Chapter 3 provides an overview of the experiment details. Chapters 4 and 5 summarize HVS and laboratory testing, respectively. Chapter 6 discusses the second-level analysis. Chapter 7 lists key findings of the study and provides recommendations for implementation.