纳米TiO2协同纳米ZnO/SBS复合改性沥青耐紫外光老化性能评价

Evaluation on Anti-UV Aging of Nano-TiO2 Coordination Nano-ZnO/SBS Composite Modified Asphalt

高海拔地区强烈紫外光辐照易使沥青路面老化,特殊环境因素要求沥青路面中黏结料须具有良好耐老化性,纳米材料以其独特优点已成为改性沥青研究的重要方向,而纳米材料在沥青中易发生团聚是制约该发展的重要瓶颈。以纳米ZnO、纳米TiO2、聚合物SBS为改性剂,运用硅烷偶联剂(KH-560)对纳米材料表面进行修饰,在此基础上研究基质沥青、SBS改性沥青、纳米ZnO/SBS改性沥青、纳米ZnO/纳米TiO2/SBS复合改性沥青紫外光老化前后物理性能演变规律,利用场发射扫描电镜结合能谱分析(SEM/EDS)研究老化前后纳米ZnO/纳米TiO2/SBS复合改性沥青中Zn、Ti特征元素含量变化及纳米材料分布形态,揭示耐光老化机理。结果显示:经过修饰后的纳米材料在沥青中分散均匀,纳米材料和沥青相容性得到明显改善,在制备过程中两者发生化学反应;紫外光老化后,纳米ZnO/纳米TiO2/SBS复合改性沥青延度保留率为87.72%,软化点增量降幅61.32%,耐老化性能最佳,其老化机理是纳米TiO2对波长为365 nm紫外光波具有良好吸收作用,而纳米ZnO在该波长辐照下易发生光分解,活性降低。

Strong ultraviolet radiation causes the asphalt pavement to age in high altitude area,and this special environment characteristic requests that the binder in the asphalt pavement must have the typical light resistance ageing.The nano-material becomes the important direction of the modified asphalt research with the unique merit,but the nano-material in the asphalt middle of agglomeration is an important bottleneck restricting development.In this paper,nano-ZnO,nano-TiO2 and polymer SBS were used as modifiers,and silane coupling agent(KH-560)was used to modify the surface of nano-materials.On this basis,the physical properties index evolution of matrix asphalt,SBS modified asphalt,nano-ZnO/SBS modified asphalt and nano-ZnO/nano-TiO2/SBS composite modified asphalt before and after UV aging were studied.The content change rate of characteristic elements Zn and Ti in nano-ZnO/nano-TiO2/SBS composite modified asphalt before and after UV aging and the distribution of nano-materials were studied by means of SEM/EDS,revealing the mechanism of UV aging resistance.These results show that the surface-modified nano-materials are uniformly dispersed in asphalt,the compatibility of nano-materials and asphalt is obviously improved,and chemical reaction takes place during the preparation process.After UV aging,the ductility retention rate of nano-ZnO/nano-TiO2/SBS composite modified asphalt is 87.72%,the increment of softening point decreases by 61.32%,and the resistance to UV ageing is the best,and the ageing mechanism is that nano-TiO2 has a good absorption effect on the UV wave with wavelength of 365 nm,while nano-ZnO is prone to photo-degradation and activity reduction.