Study on bond properties between RAP aggregates and virgin asphalt using Binder Bond Strength test and Fourier Transform Infrared spectroscopy

• An innovative coating treatment was modified to prepare artificial RAP substrates.
• A good correlation was found between asphalt film thickness and aging severity.
• In general, RAP brought enhancement to bond properties under dry conditions.
• Poor blend between RAP and virgin asphalt could lead to more water damage.
• A proper aging level may exist at which RAP can provide optimum bond properties.

Since the aged asphalt film coating Reclaimed Asphalt Pavement (RAP) aggregates has prevented virgin asphalt from directly attaching to the aggregates, the mechanism behavior developed between RAP aggregates and virgin asphalt should be considered differently. In order to directly measure bond strength between RAP aggregate and virgin binder, the Binder Bond Strength (BBS) test was performed, and artificial coated RAP substrates were prepared employing an innovative coating treatment. The aged asphalt film thickness and the aging level of RAP substrate, combined with dry and wet curing conditions were assessed regarding to their impact on bond strength. Fourier Transform Infrared (FTIR) spectroscopy was also utilized to investigate the effect of film thickness and aggregate type on aging properties.According to BBS test results, existence of aged asphalt film had positive effects on bond properties under dry conditions. Moisture weakened this enhancement and induced more debond at the diffusion zone where the aged film and virgin asphalt blend. A proper aging level may exist at which RAP can provide optimum bond properties. Moreover, through FTIR spectroscopy, a good correlation between oxidation and film thickness was observed.