Effect of optimum rejuvenator dosage on the performance of 100% recycled asphalt binder

Determination of optimum rejuvenator dosage is critical to the performance of 100% hot recycled asphalt mixtures. Further, at the optimum dosage, the rejuvenated binder is expected to have chemical and mechanical properties similar to the targeted virgin/control binder. The present study used waste engine oil (WEO) and tall oil (TO) to rejuvenate recycled asphalt pavement (RAP) binders obtained from two different sources. The optimum dosages of the rejuvenators were evaluated using different test procedures. The chemical, morphological, and performance characteristics of the RAP binders rejuvenated at the optimum dosages were studied. True fail temperature was identified as the most suitable parameter for estimating the optimum rejuvenator dosage. The optimum rejuvenator dosages of WEO were found to be 19% and 18%, respectively, for the two RAP sources considered in this study. The corresponding dosages for TO were estimated as 17% and 14%, respectively. Saturates-aromatics-resins-asphaltenes (SARA) analysis indicated that the rejuvenators were able to restore the chemical properties of the RAP binders, the degree of restoration being a function of the rejuvenator type and stiffness of the RAP binder. Results from atomic force microscopy (AFM) analysis confirmed that the rejuvenated binders showed the formation of new structures that were unique for different combinations of RAP binder and rejuvenator. Rutting and fatigue characteristics, evaluated using multiple stress creep and recovery (MSCR) and linear amplitude sweep (LAS) tests, respectively, improved after rejuvenating the RAP binders. In terms of rejuvenation and performance characteristics, TO showed better results in comparison to WEO.