Performance Evaluation of Thermosetting and Thermoplastic Polyurethane Asphalt Mixtures

Polyurethane (PU) asphalt binders have been proved to be a promising class of paving materials for steel bridge deck or highway road. This study further evaluated the performance of a thermosetting-PU (TS-PU) asphalt mixture and a thermoplastic-PU (TP-PU) asphalt mixture by conducting a series of tests to identify their advantages and disadvantages compared with common mixtures in practical engineering. It was demonstrated that the prepared PU asphalt mixtures exhibited better flexibility and low-temperature cracking resistance than an epoxy asphalt mixture, and the TP-PU asphalt mixture was better than a styrene-butadiene-styrene (SBS)-modified asphalt mixture. Although PU asphalt mixtures were worse than an epoxy asphalt mixture, they usually were markedly better than SBS-modified asphalt mixture in strength properties, high-temperature rutting resistance, fatigue resistance, and fuel erosion resistance. However, the water stability of the prepared PU asphalt mixtures was unsatisfactory. It also was demonstrated that the variance of the performance between PU asphalt mixtures was significant, and this variance was associated strongly with properties of PU asphalt binders, which suggests the importance of PU asphalt binder for obtaining a PU asphalt pavement with tailored performance.