The　use　of　reclaimed　asphalt　pavement　(RAP)　is　believed　to　contribute　significantly　towards　overall　energy　conservation　and　environmental　protection　efforts.　However,　the　recycling　of　aged　binder　from　RAP　requires　a　fundamental　understanding　of　the　interaction　mechanism　between　such　rejuvenators　with　recycled　and　unmodified　binders.　This　study　quantitatively　investigated　the　impact　of　such　agents　in　combination　with　the　aging-rejuvenation　process　and　other　binder　modifiers　(SBS,　crumb　rubber,　and　a　high　viscosity　modifier)　on　the　fractional　composition,　rheology,　and　colloidal　structural　stability　of　asphalt　binders.　Based　on　these　results,　a　rejuvenation　index　(RI)　was　proposed　to　quantitatively　evaluate　the　rejuvenation　of　aged　asphalt　binder.　Aging　increased　the　proportion　of　resins　and　asphaltenes　of　asphalt　binders　which　resulted　in　the　decrease　of　its　rheological　properties.　After　the　addition　of　the　rejuvenators,　the　complex　modulus　of　all　aged　binders　were　reduced.　Certain　rejuvenators　transformed　up　to　5　percentage　points　of　asphaltenes　into　other　fractions.　The　aromatic　oil-based　rejuvenator　showed　the　best　rejuvenation　of　unmodified　asphalt　binder,　but　theRI　was　only　0.33.　Overall,　the　results　implied　that　rejuvenation　of　asphalt　binders　is　a　complex　topic　and　further　studies　should　be　conducted　to　correlate　the　rheological　behaviour　with　rejuvenation　mechanisms　beyond　chemical　fractions.