Comprehensive Evaluation of Properties and Performance of Asphalt Mixtures with Reactive Isocyanate and Styrene-Butadiene-Styrene-Modified Binders

Abstract

The purpose of this study was to conduct a performance evaluation to investigate the effect of a newer type of asphalt binder modification system and to demonstrate the importance of performance prediction modeling over use of only mix stiffness or a single performance index property to compare asphalt binder modification systems. Four asphalt mixtures with different amount of modifiers were evaluated in this study. Laboratory characterization included complex modulus, direct tension cyclic fatigue, cracking tolerance index, disk-shaped compact tension, indirect tensile creep and strength, and Hamburg wheel tracking tests. In addition, advanced performance prediction programs including AASHTOWare Pavement ME, FlexPAVE, and IlliTC were utilized to predict mixture performance. Based on the results of laboratory testing and performance simulations, the reactive isocyanate-based modifier (RIB) and styrene-butadiene-styrene (SBS) modifiers improved the properties and performance of the control mixture with respect to rutting and fatigue cracking but may have a negative effect with respect to thermal cracking. Modification of the control mixture with the combination of RIB and SBS balanced good rutting and fatigue cracking performance while maintaining thermal cracking resistance, indicating that the RIB + SBS modification may be a good candidate for further evaluation and field trial consideration.