UC Davis

The aging of asphalt concrete is mainly governed by the aging of the asphalt binder, which is a naturally occurring organic hydrocarbon. Both chemical and rheological properties of asphalt binder are expected to change as aging continues. The pavement industry is increasing the use of different recycled materials in the construction and rehabilitation of flexible pavements to preserve natural resources, save costs, and reduce environmental emissions. The aged binder from recycled materials is expected to alter the binder properties and its aging characteristics in the new mix. In this study, 3 different virgin base binder types (PG 64-16, PG 58-22, and PG 70-10) and 7 different binder blends containing recycled binders (up to 100 % binder replacement) were subjected to different aging conditions. The rheological and chemical properties of these binders were characterized using a dynamic shear rheometer and Fourier transform infrared spectroscopy, respectively. It was found that the Glover-Rowe parameter distinctively captured the change in binder rheological properties with aging for the different binder blends. A good correlation (R2value of 0.83-1.00) was observed between binder chemical and rheological properties. The source and performance grade of the base binder were found to govern the correlation between the rheological and chemical properties of the blended binder. Hamburg wheel tracking (for rutting and moisture sensitivity) and indirect tensile asphalt cracking test (for fracture) tests were conducted on asphalt mixes maintaining the same blended binder ratios. The laboratory mix performance parameters were found to correlate well with the properties of the blended binders. Therefore, properties of the blended binders can be an important source of information for predicting the performance of asphalt mixes containing recycled materials.