Laboratory evaluation of asphalt blends of recycling agents mixed with aged binders

For both environmental and financial reasons, the use of reclaimed asphalt pavements (RAP) needs to be maximized. In this study, rejuvenators and soft asphalt cements were used as recycling agents. Aged binders recovered from field projects were mixed with various percentages of recycling agents to produce asphalt blends. The engineering and chemical properties of the blends were evaluated in the laboratory using binder tests including viscosity, dynamic shear rheometer, gel permeation chromatograph, and Fourier transform infrared spectroscopy. With high RAP contents, the test results indicated that hardened binders may be restored to proper performance characteristics using rejuvenators. The recycling process produces a final blend that is similar to a reference binder in terms of viscoelastic properties. The blends mixed with rejuvenators behaved better under fatigue than those with softening agents. The large molecular size was shown to be a characteristic of an asphalt blend, and may be used as a valuable indicator to design pavement recycling projects. The formation of the carbonyl area in aged asphalt was reduced by adding recycling agents, which changed the physical properties of the blended binder in a predictable manner. A model was developed to detect the content of recycling agents.