To analyze the effect of polyol on polyurethane (PU)-modified asphalt, three different soft segments of polyurethane were synthesized, and we utilized the reaction of MDI (diphenylmethane diisocyanate) with PU650, PU1000, and PU1400. With respect to molecular weight, the effect of polyol on the performance of modified asphalt was analyzed, and the asphalt was modified by using three different polyurethanes. To analyze the PU samples, the Fourier transform infrared spectroscopy (FTIR) tests and gel permeation chromatography (GPC) tests were selected; by contrast, to analyze the rheological properties and modification mechanism of asphalt, the dynamic rheology test (DSR), low-temperature bending creep test (BBR), multi-stress repetitive creep test (MSCR), FTIR, and differential scanning calorimetry (DSC) were selected. The results indicate that the molecular weight of polyol affects the molecular structure of polyurethane, the distribution of soft and hard segments, the content of soft segments, and the distribution of asphaltene in asphalt; thus, the asphalt modification effect occurs differently. The storage stability and high-temperature stability of the polyurethane-modified asphalts that were synthesized using three different polyols (i.e., polyols that exhibit different molecular weights) did not differ considerably, and the PU1400-modified asphalt exhibited the best low-temperature performance.
To improve the inferior stability in high‐viscosity asphalt prepared using styrene‐butadiene‐styrene block copolymer (SBS) and to simplify the preparation process, a novel high‐viscosity modifier (STP) was prepared with SBS, terpene‐styrene resin (TSR) and plasticizer. Its inherent properties, optimal dosage, and modification effect were investigated. The results show that STP has lower component melting temperature and stronger polarity, combined with good thermal stability, ensuring that STP possesses a better modification effect on asphalt. 14.5–17.6 wt% was determined as the appropriate content of STP. The incorporation of STP improved the rutting resistance and elasticity percentage of the asphalt. The zero shear viscosity (ZSV) of asphalt fitted by the Carreau model showed that STP increased the cohesion of the asphalt system and improved the high‐temperature deformation resistance. The small non‐recoverable creep compliance value proves that the STP high‐viscosity asphalt (STP‐HVA) exhibits excellent resistance to permanent deformation at high‐temperatures while displaying low‐stress sensitivity and achieving an extremely heavy traffic rating. STP confers greater flexibility to asphalt to eliminate low‐temperature cracking phenomenon. Smaller CMAI and PAAI values demonstrate that STP‐HVA exhibits outstanding aging resistance. TSR effectively improves the compatibility of SBS and base asphalt, and STP particles are finely dispersed and uniform. The preparation process is mainly physical modification, accompanied by chemical reactions.
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