基于SBS改性剂和聚氨酯前驱体化学改性剂(polyurethane-precursor chemical modifier,PRM)潜在的物理化学空间交联特性,制备了SBS‒PRM复合改性沥青.通过三大指标(针入度、软化点、延度)、动力黏度明确复合改性沥青的高黏特征;采用频率扫描试验、多应力蠕变恢复试验、线性振幅扫描试验以及弯曲梁流变试验研究了改性沥青的流变特性;利用傅里叶变换红外光谱、原子力显微镜和荧光显微镜解释了SBS‒PRM物理化学复合改性机理;最后验证了沥青混合料性能.结果表明,PRM通过化学反应改变了沥青分子结构并提升SBS与沥青的相容性,形成了空间交联结构增强沥青的黏度、抵抗高温永久变形、低温开裂和疲劳破坏的性能;利用SBS‒PRM复合改性沥青制备的SMA‒13混合料具有良好的高温抗车辙、低温抗裂、抗水损性能.
SBS-PRM Composite Modified Asphalt Based on Physicochemical Spatial Crosslinking Structure
Based on the potential physicochemical spatial crosslinking properties of SBS modifier and polyurethane-precursor chemical modifier(PRM),the SBS-PRM composite modified asphalt was prepared.The high viscosity characteristics of the asphalt samples were clarified by penetration,softening point,ductility,and dynamic viscosity test.Rheological characterization of modified asphalts was investigated using frequency sweep test,multiple stress creep recovery test,linear amplitude sweep test,and bending beam rheometer test.The physicochemical composite modification mechanism was explained using Fourier transform infrared spectroscopy,atomic force microscopy,and fluorescence microscopy.Finally,the pavement performance of asphalt mixtures was verified.The results show that PRM changes the molecular structure of asphalt through chemical reaction which contributes to improving the compatibility of SBS with asphalt.The formation of spatial crosslinked network structure enhances the viscosity,resistance to high-temperature permanent deformation,low-temperature cracking,and fatigue damage of asphalt.In addition,significant advantages are obtained in high temperature rutting resistance,low temperature cracking resistance,and moisture damage resistance of SMA-13 mixtures prepared with composite modified asphalt.
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