Field Aging Evaluation of Asphalt Binders by Chemical and Rheological Characterization
Two field aged asphalt binders were evaluated in the study. The binders were extracted and recovered from samples that were collected from two 4 cm HMAs in the field at different times. Chemical and rheological tests were performed to quantify the aging. The binder’s chemical properties were evaluated by SARA fractions (saturates, asphaltenes, resins and aromatics), gel permeation chromatography (GPC), nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. The rheological tests were carried out in a dynamic shear rheometer (DSR). Dynamic shear modulus (|G*|) and multiple stress creep and recovery (MSCR) tests were performed to evaluate the change in the binders rheological properties. Both chemical and rheological results confirm the continuous aging of the asphalt binder in the field, mostly up to 24 months after construction, although the greatest aging occurs during mixing. Rheological results indicated that after 36 months of field aging, the two binders were performed similarly even though they aged differently.