盐冻融循环条件下沥青高温流变性能及微观结构

利用动态剪切流变仪(DSR)和原子力显微镜(AFM)对冻融循环前后的基质沥青和胶粉改性沥青进行测试,比较分析了不同盐浓度和冻融循环次数下两种沥青的动态黏弹参数及微观结构,并测试了冻融前后两种沥青的基本指标。结果表明:经历冻融循环后,基质沥青储存模量和车辙因子均增加,疲劳因子减小,而胶粉改性沥青没有明显变化,冻融循环增加了基质沥青的高温弹性性能,但显著降低了抗疲劳性能,而冻融循环对胶粉改性沥青的高温性能影响不大;AFM观测表明基质沥青出现"蜂形"结构,冻融循环后"蜂形"变大、变长,而胶粉改性沥青的结构几乎没有变化,因此北方寒冷地区使用胶粉改性沥青作为路面材料更具优势。

High temperature rheological properties and microstructures of asphalt under salt freezing cycles

The Dynamic Shear Rheometer (DSR) and Atomic Force Microscope (AFM) were utilized to test matrix asphalt and rubber-modified asphalt before and after freeze-thaw cycles.The dynamic viscoelastic parameters and its microstructure had been compared and analyzed under different salt concentrations and cycle times,and three major indexes of two kinds of asphalt had also been tested before and after freeze-thaw cycles.The results show that storage modulus and rutting factor of matrix asphalt increase,and fatigue factor decreases,but rubber-modified asphalt has no significant change after freeze-thaw cycles,while freeze-thaw cycle increases the high temperature elastic property,but it decreases anti-fatigue ability of matrix asphalt greatly,and makes little influence on high temperature rheological properties of rubber-modified asphalt.AFM observations show that matrix asphalt appears "bee structures",which becomes bigger and longer after freeze-thaw cycles,but rubber-modified asphalt has no significant change,so rubber-modified asphalt used as pavement material has more advantage in north cold region.