盐冻循环条件下改性沥青的微观结构及重复蠕变特性

为考察在融雪盐环境下路面材料的性能变化情况,对内蒙古寒冷地区常用的SBS(苯乙烯-丁二烯-苯乙烯嵌段共聚物)改性沥青和胶粉改性沥青利用动态剪切流变仪(DSR)进行重复蠕变试验,利用原子力显微镜(AFM)进行微观结构观测,比较分析盐冻循环前后两种沥青的微细观结构以及流变学性能的变化,为寒冷地区道路路面材料的选择和使用提供参考依据。AFM测试发现,SBS改性沥青出现"蜂形"结构,冻融循环后,"蜂形"结构出现不同变化;胶粉改性沥青未出现"蜂形"结构,冻融循环后胶粉改性沥青表面形貌相差不大;重复蠕变试验结果显示:冻融循环前后SBS改性沥青和胶粉改性沥青永久变形与卸载瞬时应变的比值(εP/εL)在加载初期均随着加载次数的增加而增加,一定次数后达到稳定状态;冻融循环后SBS改性沥青的εP/εL降低,胶粉改性沥青的εP/εL基本不变;利用Burgers模型拟合得到蠕变劲度的黏性成分G_v,冻融循环后SBS改性沥青G_v值小于原样SBS改性沥青,胶粉改性沥青G_v值大于原样胶粉改性沥青,且两种沥青水冻循环与盐冻循环G_v值差别不大。胶粉改性沥青具有更好的高温使用性能。

The microstructure and repeat creep property of modified asphalt under the salt freezing cycle

In order to investigate the changes performance of pavement materials under the snow melting salt,the dynamic shear rheometer (DSR) was used to study repeat creep property of SBS (styrene-butadiene-styrene blockcopolymer) modified asphalt and rubber powder modified asphalt in Inner Mongolia region,and the atomic force microscope (AFM) was used to observe microstructure,the micro structure and the rheological properties of the two kinds of asphalt were compared and analysed after salt freezing cycles.AFM tests indicate that there are some "bee" structures in SBS modified asphalt,and the quality and size of "bee" structures change after freeze-thaw cycles;But there is not "bee" structures in rubber modified asphalt.At the same time,there is little change in microstructure before and after freeze-thaw cycles.DSR test results show that the ratio of transient strain to unloading instantaneous strain (εP/εL) of SBS modified asphalt and rubber powder modified asphalt increases at the beginning of the loading and then reach a steady state after a certain number of loading cycles.The εP/εL of SBS modified asphalt reduces and the εP/εL of rubber powder modified asphalt does not change after freeze-thaw cycles.Burgers model was used to fitting the parameter Gv.The Gv of SBS modified asphalt reduces,while it is increased for the rubber powder modified asphalt after freeze-thaw cycles.And the Gv of asphalt after water freezing has little difference from that after salt freezing.Rubber powder modified asphalt has better high temperature performance.