Impact of Virgin Binders on IDEAL-CT Results of RAP Asphalt Mixtures

Abstract

This study evaluated the impact of virgin binders on the Indirect Tensile Asphalt Cracking Test (IDEAL-CT) results of asphalt mixtures containing reclaimed asphalt pavement (RAP). A total of 14 RAP mixtures were tested, covering two U.S. climate zones, four mix designs, and six virgin binders. Each virgin binder underwent rheological characterization at three aging conditions: unaged, rolling thin film oven (RTFO) plus 20-hour pressure aging vessel (PAV) aging, and RTFO plus 40-hour PAV aging. The test results showed that using a softer virgin binder improved the IDEAL-CT results, whereas using a polymer modified asphalt binder did not show similar benefits. The impact of binder source on the IDEAL-CT results was found to vary depending on the RAP mix design. Moreover, the modified Glover-Rowe (G-R) parameter at 15°C and 10 Hz after 40-hour PAV aging demonstrated the strongest correlation to the IDEAL-CT results, suggesting its potential utility as a mix design tool for screening virgin binders to assess the cracking resistance of RAP mixtures.