盐冻循环条件下两种沥青的微观结构及高低温性能

利用原子力显微镜(AFM)、动态剪切流变仪(DSR)和弯曲梁流变仪(BBR)对冻融循环前后的基质沥青和苯乙烯-丁二烯-苯乙烯三嵌段共聚物(SBS)改性沥青进行了微观结构观测和高低温性能测试。试验结果表明:经冻融循环后,沥青"蜂形"结构的数量和尺寸出现不同变化,基质沥青中沥青质含量增加且分散状况变差,SBS改性剂三维网状结构遭到破坏;基质沥青的高温性能有所提升,抗疲劳性能降低,SBS改性沥青的高温性能降低,抗疲劳能力提升;融雪盐浓度增大在一定程度上降低了基质沥青的低温抗裂能力,融雪盐浓度为4wt%时,SBS改性沥青的低温抗裂能力得到提高。SBS改性沥青高低温性能总体上优于基质沥青,建议北方等寒冷地区尽量选用SBS改性沥青作为路面材料。

Microstructure and high-and-low temperature performance of two kinds of asphalt under salt freezing cycle

The microstructure and the high-and-low temperature performance of matrix asphalt and styrene butadiene-styrene tri-block copolymer(SBS) modified asphalt before and after the salt freezing cycle were studied by the AFM,DSR and BBR,respectively.The results indicate that the asphaltene content of matrix asphalt increases and the dispersion situation of matrix asphalt gets worse,and three-dimensional network structure of SBS modifier is destroyed due to the number and size of asphalt "bee" structures changing after freeze-thaw cycles.The high temperature performance of matrix asphalt increases slightly and anti-fatigue performance decreases after the salt freezing cycle,while high temperature property of SBS modified asphalt decreases and the fatigue properties increases.To a certain degree,the increase of salt concentration make the low temperature cracking resistance of matrix asphalt reduce.However,when the concentration of salt reaches up to 4wt％,the low temperature cracking resistance of SBS modified asphalt is improved.Hence,the high-and-low temperature performance of SBS modified asphalt is better than that of matrix asphalt.It is recommended that SBS modified asphalt should be chose as the pavement material in the cold region as far as possible.