Bitumen extracted from reclaimed asphalt pavement (RAP) materials is known as reclaimed asphalt binder (RAB). Many studies have been conducted to evaluate effect of the rejuvenating agents in physical-rheological and chemical properties of the RAB. The aim of this study is to evaluate the effects of other modifiers such as soft bitumen and polymer modified bitumen (PMB) in performance of RAB-containing asphalt binders in comparison with rejuvenators. In this study, changes in physical-rheological parameters and chemical structure of RAB-containing binder mixes were investigated by different modifiers including softer bitumen, rejuvenator and the waste polymer modified bitumen (WPMB). Penetration, softening point, rotational viscosity, dynamic shear rheometer (DSR), saturates, aromatics, resin and asphaltenes (SARA) fractionation, Fourier transform infrared (FTIR) spectroscopy and atomic force microscopy (AFM) tests were performed for this purpose. Results showed that the rejuvenator and softer bitumen had the greatest effect on the improvement of the physical-rheological and chemical properties of the RAB-containing binder mixes, respectively. So that, the rejuvenator, softer bitumen and the WPMB improved fatigue resistance and chemical structure of the RAB-containing binder mixes to the level of that of the virgin binder when the RAB content was limited to 100%, 50% and 30% RAB, respectively. Moreover, results indicated that there are good correlations between chemical and physical-rheological parameters. Meanwhile, colloidal index of the binder mixes was a good indicator for estimating the superpave fatigue parameters of asphalt binders.
