Optimization of recycled asphalt binder with eco-friendly additives: Activation energy and bonding properties

To address the challenges of developing eco-friendly and sustainable asphalt binders, this study explores the use of three primary waste materials from the automobile and pavement industries: crumb rubber (CR), waste engine oil (WEO), and reclaimed asphalt pavement (RAP). While previous studies have explored the use of individual or dual rejuvenators, limited research has examined multiple additives for rejuvenating 100 % RAP binders. This study addresses this gap by evaluating the effect of sequentially adding CR, WEO, and SBS on the aging, cracking, rheological, and bonding properties of laboratory-produced RAP binders. Kinetic modeling (via Arrhenius equations) was employed to quantify aging activation energy ( E aa ), cracking activation energy ( E ac ), and viscous flow activation energy ( E v ). Four rejuvenated binders were prepared using different contents of additives (6 % CR, 7.5 % and 10 % WEO, and 2 % and 3 % SBS), and their performance was compared to virgin and RAP binders. Results indicate that adding 10 % WEO, 6 % CR, and 3 % SBS improves fatigue resistance, as evidenced by higher cracking activation energy and improved adhesive bond strength. The blend with 7.5 % WEO, 6 % CR, and 3 % SBS demonstrated superior high-temperature performance in multiple stress creep and recovery (MSCR) tests. Notably, the blend with 10 % WEO, 6 % CR, and 2 % SBS exhibited the lowest viscosity among the rejuvenated binders, enhancing workability and flow characteristics. These findings demonstrate the potential of multi-additive blends to improve the durability and sustainability of RAP binders, offering a promising solution for extending pavement service life. • WEO, CR, and SBS improved fatigue resistance and durability of aged binder. • Incorporation of rejuvenators improved the rheological characteristics of aged asphalt binder. • Higher WEO content improved fatigue performance but reduced rutting resistance. • light components from WEO enhanced the surface energy and bonding properties.