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Styrene-butadiene-styrene (SBS)-modified binders used in porous asphalt mixtures are prone to rapid aging, resulting in the degradation of both the bitumen phase and the cross-linked SBS polymer network. This dual deterioration severely limits the recyclability of reclaimed asphalt pavement (RAP) containing polymer-modified binders. Conventional rejuvenation strategies primarily focus on softening the aged bitumen, often overlooking the restoration of polymer functionality, which is essential for recovering elasticity, durability, and high-temperature performance. This study addresses this gap by decoupling rejuvenation into two core dimensions, what is being repaired (bitumen vs SBS) and how it is being repaired (physical vs chemical), to develop and evaluate four rejuvenator families: (1) softening oils targeting the bitumen phase; (2) oil-SBS blends that reintroduce fresh polymer; (3) methylene diphenyl diisocyanate (MDI) that chemically reconnects SBS chains; and (4) chemo-physical systems combining oil, SBS, and MDI to address both phases synergistically. A comprehensive suite of characterization techniques, including Fourier-transform infrared spectroscopy (FTIR), gas chromatography-flame ionization detection (GC-FID), dynamic shear rheometer (DSR) master curves, multiple stress creep and recovery (MSCR), creep-relaxation, linear amplitude sweep (LAS), fluorescence microscopy, and environmental scanning electron microscopy (ESEM), was used to link molecular mechanisms to rheological and morphological outcomes. Results showed that oils alone softened the binder and improved fatigue resistance but diluted the polymer signature and failed to restore network elasticity. Oil-SBS blends improved SBS content and elasticity but exhibited incomplete network formation. MDI improved elasticity and stiffness but at the cost of brittleness. Chemo-physical systems reconciled these trade-offs, enabling simultaneous softening, polymer replenishment, and network rebuilding, achieving properties comparable to or better than the unaged binder. To validate these mechanisms under practical conditions, rejuvenators were applied to 50% recycling blends in both binder and mastic forms, confirming their performance in realistic recycling scenarios. These findings offer mechanistic insights and practical guidance for designing next-generation rejuvenators to enable sustainable recycling of SBS-modified RAP.