Impact of Binder Rheology and Source on Cracking and Cost of FHWA EDC-6 Target Overlay Solutions

Abstract: This study evaluated the effects of rheological characteristics and binder sources with the same Performance Grade (PG) on intermediate-temperature cracking and the life-cycle costs of three FHWA Every Day Counts (EDC-6) Targeted Overlay Pavement Solutions (TOPs): Asphalt Rubber Gap-Graded (ARGG), High-Polymer Thin Overlay (HPTO), and Stone Matrix Asphalt (SMA). Two asphalt rubber binders (AR1 and AR2) and two polymer-modified binders (PMA1 and PMA2) were used.
Master curves were constructed to characterize the stiffness-temperature response of the binders. From the master curves, Crossover Frequency (ω_c) and Rheological index (R-value) as well as the Glover-Rowe parameter (G-R) and its modified version, G-Rf, were calculated to track the relative rate of aging and cracking susceptibility among different binders. The Indirect Tensile Asphalt Cracking Test (IDEAL-CT) was used to evaluate the intermediate-temperature cracking resistances of the TOPS mixtures. A performance interaction diagram which considers mixture toughness and brittleness behaviors and their interaction, was established to provide a more comprehensive interpretation of the IDEAL-CT results. Life cycle cost analyses (LCCA) were done to determine if there was a significant cost difference among the three TOPS.
The results showed significant variations in the rheological characteristics and the aging resistances of AR and PMA binders based on their source, which affected the intermediate-temperature cracking resistances of the TOPS mixtures. This highlighted the importance of careful binder selection in pavement design and maintenance to ensure optimal performance. The LCCA indicated no significant difference in the net present value (NPV) of the three TOPS.