基于流变学的木质素纤维复配SBS改性沥青高低温性能及微观特性研究

High and Low Temperature Performance and Micro-structure of Wood Fiber Compounded SBS Modified Asphalt based on Rheology

为研究木质素纤维复配SBS改性沥青胶浆的流变特性及微观作用机理,制备了不同掺量的木质素纤维/SBS复合(WF/SBS)改性沥青,利用动态剪切流变(DSR)以及弯曲梁流变(BBR)试验分析了复合改性沥青的高、低温流变性能,通过针入度、软化点与延度试验评价了其基本物理性能;借助扫描电子显微镜(SEM)对改性沥青的微观结构、改性共混机理进行了观察与分析。研究结果表明:木质素纤维对SBS改性沥青的高温性能改善效果显著,低温抗裂性改善效果一般。在高温状态下,WF/SBS改性沥青表现出更优的弹性特性,具有更宽的相位角变化范围,更低的温度敏感性。基于扫描电镜SEM试验可知,WF/SBS是一种以物理改性为主的共混体系,木质素纤维的脱黏与拔出效应以及与SBS改性沥青复配后形成的“点+线”式的空间网络结构是促使其高温稳定性提升的主要原因。当木质素纤维掺量为0.2%时,其微观分布形态最优,掺量增加至0.3%时开始出现团聚现象。

In order to study the rheological properties and microscopic mechanism of wood fiber compounded SBS modified asphalt, WF/SBS composite modified asphalt with different dosage of wood fiber is prepared. The rheological properties of high and low temperature composite modified asphalt are analyzed by dynamic shear rheological(DSR) and bending beam rheometre(BBR) tests. The physical properties are evaluated by needle penetration, softening point and ductility tests, and the microstructure and blending mechanism of modified asphalt are observed and analyzed by means of scanning electron microscope(SEM). The results show that wood fiber has a significant improvement effect on high temperature performance of SBS modified asphalt, and a general improvement effect on low temperature crack resistance. At high temperature, WF/SBS modified asphalt shows better elastic properties, wider phase angle range and lower temperature sensitivity. Based on the scanning electron microscopy(SEM) test, it can be seen that WF/SBS is a blend system mainly based on physical modification, and the de-bonding and pull-out effect of lignin fiber and the "point + line" network structure formed after mixing with SBS modified asphalt are the main reasons to improve its high temperature stability. When the content of wood fiber is 0.2%, its micro-structure distribution morphology is the best, and when the content of wood fiber increases to 0.3%, agglomeration phenomenon begins to appear.