Performance Optimization of Aged Binder-Rich Materials Using Kinetics-Based Analysis of Fine Aggregate Matrix

The utilization of reclaimed asphalt pavement (RAP) is often limited by challenges like particle agglomeration and variability, which necessitate advanced processing methods such as refined decomposition (RD). This technique enables better separation and recovery of aged binder-rich materials, which facilitates the high-value and high-content utilization of RAP. However, achieving balanced performance requires careful optimization of this recycled fraction. To address this, the present study proposes a kinetics-based approach to determine the optimum content of this recycled material for balanced performance. The approach employs RD-processed RAP fractions (0–3 mm) for fine aggregate matrix (FAM) characterization. This characterization calculates the activation energies of key distresses: moisture damage ( E S ), permanent deformation ( E P ), fatigue cracking ( E a c ), and oxidative aging ( E a c r ). The optimal recycled material (ORM) content is identified at the intersection of these activation energy curves, balancing critical performance factors. The framework was validated using different binder types [Pen-70, styrene-butadiene-styrene (SBS)-modified] and gradations (AC-13, SUP-20), confirming its versatility and potential to improve the design. The results show that both aggregate gradation and binder type are crucial in determining the ORM content. The SBS-modified binders and finer aggregate gradations (AC-13) enhance the overall performance and allow a higher ORM content of 38%. Meanwhile, SUP-20 with SBS-modified and AC-13 with Pen-70 binder exhibit ORM content of 30% and 20%, respectively. This approach provides a robust framework for optimizing the use of aged binder-rich recycled materials while maintaining a balanced performance.