Comparisons of the properties and sustainability of asphalt binders modified with reactive thermosetting polymers

Reactive thermosetting polymers have been used to enhance the mechanical properties of asphalt binders. In this study, asphalt binders modified with two of such modifiers- epoxy resin and polyurethane, are comprehensively evaluated and compared for differences in properties and sustainability considerations. Fourier-transform infrared spectroscopy, laser-scanning-confocal fluorescence microscopy, and scanning electron microscopy were used to examine the physicochemical properties of modified binders. Workability, storage stability, compatibility, and mechanical properties of binders were comprehensively evaluated, with comparisons on cost, energy consumption, and emission. Analysis results indicate that both modifiers (at the added dosage) create 3D- cross-linked network structures and continuous phase, and the network structure in polyurethane-modified binders is better organized than that in epoxy-modified binders. Compared to polyurethane-modified binder, epoxy-modified binder shows better workability, worse compatibility, lower flexibility, and higher strength. Polyurethane-modified binder requires less energy for activation and curing but has a limited window time for construction. Compared to polyurethane-modified binder and mixture, although epoxy-modified asphalt materials are associated with higher energy consumption, cost, and global warming potential emission, they generate less photochemical ozone creation potential and acidification potential emission. The comparisons provide comprehensive and multifaceted information on potentials of using the two reactive thermosetting polymers in asphalt pavements.