A multifaceted purpose-oriented approach to evaluate material circularity index for rejuvenated recycled asphalt...

This study investigates the impact of different mechanical properties, test procedures, and environmental and economic factors on the Material Circularity Index (MCI) of rejuvenated recycled asphalt mixtures. Four mixtures, including new and rejuvenated mixtures with 35%, 50%, and 65% reclaimed asphalt pavement (RAP), were evaluated using resilient modulus, moisture susceptibility, indirect tensile fatigue, semi-circular bending, and dynamic creep tests. A novel definition of MCI was introduced, integrating cost, CO₂ emissions, and mechanical properties. Results indicate that the 50% RAP mixture consistently performed best across a range of scenarios, especially in varying climates and when multiple performance criteria were considered, with an MCI ranging from 0.38 to 0.83. Meanwhile, the 65% RAP mixture was optimal when cost and environmental considerations were prioritized, particularly in moderate to low temperatures. The findings also imply the importance of selecting appropriate performance parameters and test methods, as the choice of dynamic creep test procedures was shown to significantly influence MCI values. Ultimately, this study demonstrates that the MCI can serve as a multi-conceptual index for selecting appropriate asphalt mixtures. This process ensures a sustainable, performance-based asphalt mixture selection by integrating regional conditions, performance needs, and environmental factors.