Study on the Performance of Nonionic Waterborne Polyurethane and SBS Composite–Modified Emulsified Asphalt

To address the problem of insufficient performance of styrene butadiene styrene (SBS)–modified emulsified asphalt in road maintenance, this study discusses the potential possibility of further modification of SBS-modified emulsified asphalt by nonionic waterborne polyurethane (NWPU). In this study, composite-modified emulsified asphalt (CMEA) was obtained by mixing NWPU and SBS-modified asphalt emulsions. The various performance of the asphalt was comprehensively evaluated by Fourier transform infrared (FTIR), fluorescence microscopy, temperature sweep, frequency sweep, linear amplitude sweep (LAS), multistress creep recovery (MSCR), and surface free energy tests. The results confirmed that there is an intermolecular interaction between NWPU and SBS polymer and showed that the addition of NWPU can improve the high-temperature rheological, adhesion, and fatigue performance of SBS-modified emulsified asphalt, but the hydrophilic groups introduced by NWPU also weaken the water stability of asphalt to a certain extent. When the NWPU content was 12% and 15%, the NWPU particles in the asphalt are agglomerated and cross-linked with SBS particles, which improved the viscoelastic mechanical response of the asphalt.