Property evaluation of the PRM/SBR composite modified emulsified asphalt towards low-carbon and sustainable pavements

Emulsified asphalt demonstrates notable environmental and economic benefits, particularly through its reduced energy requirements during production. However, its mechanical properties are typically inferior to conventional hot-mix asphalt. Although polymer modification is used to improve the performance of emulsified asphalt, it is difficult to meet the requirements of high-performance pavements. From the perspective of chemical modification, this study proposed a novel composite-modified emulsified asphalt, based on polyurethane-precursor-based reactive modifier (PRM) and styrene-butadiene rubber (SBR) latex. Samples of asphalt binders and their emulsified residues were characterized by macro and micro laboratory tests, including physical tests, dynamic shear rheometer test, bending beam rheometer test, fluorescence microscopy, laser particle size analyzer analysis, Fourier transform infrared spectroscopy, storage stability test, and environmental impact analysis. It is demonstrated that the use of PRM modification in emulsified asphalt can significantly improve its high-temperature rheological performance and fatigue damage resistance. The chemical reaction between PRM and asphalt generates new functional groups, forming stable chemical linkages that improve compatibility and exhibit excellent storage stability. Moreover, the PRM/SBR composite system exhibits a remarkable synergistic effect, which not only improves the high-temperature performance of emulsified asphalt but also ensures favorable low-temperature creep behavior. While maintaining the advantages of mixing at room temperature, the high-temperature performance and low-temperature crack resistance are significantly improved, which demonstrates considerable potential in the development of green and low-carbon pavement materials.