基于数字散斑相关法的聚合物改性沥青混合料抗裂性能

为分析冻融循环对苯乙烯-丁二烯-苯乙烯（SBS）和橡胶粉（CR）改性沥青混合料抗裂性能的影响，首先，分别对盐溶液冻融循环和水溶液冻融循环改性沥青混合料进行了半圆试件弯拉试验，同时采用数字散斑相关法（DSCT）对加载过程试件表面的散斑图像进行处理，提取试件表面随着载荷变化的位移场和应变场信息；然后，通过分析变形场信息确定沥青混合料的抗裂性能，并与断裂韧性试验结果进行对比。结果表明:水平应变较适合用于对沥青混合料的抗裂性能开展特性研究；由水平应变-时间曲线可知，冻融循环后SBS和CR改性沥青混合料的抗裂性能均有所劣化，且盐溶液冻融循环对沥青混合料抗裂性能的影响要大于水溶液冻融循环的；与SBS改性沥青混合料相比，CR改性沥青混合料的抗裂性能较好。所得结论表明DSCT的分析结果与断裂韧性试验的分析结果一致，采用DSCT评价沥青混合料的抗裂性能是可行的。 

Crack resistance of polymer modified asphalt mixture based on digital speckle correlation technique

In order to analyze the influences of freeze-thaw cycle on the crack resistance of styrene-butadiene-styrene (SBS) and crumb rubber (CR) modified asphalt mixtures, semicircle specimen flexural tensile tests were performed on salt solution freeze-thaw cycled and water solution freeze-thaw cycled modified asphalt mixtures firstly. At the same time, speckle images for the surfaces of specimens during the loading processes were processed using digital speckle correlation technique (DSCT), and the information of displacement field and strain field for the surfaces of the specimens changing with the load was extracted. Then, the crack resistance of asphalt mixtures was determined by analyzing the deformation field information and the results were compared with the fracture toughness test results. The results show that the horizontal strain is more suitable for the characteristic investigation on crack resistance of asphalt mixture. Both of the crack resistances for SBS and CR modified asphalt mixtures are degraded at some degree after freeze-thaw cycle, and the influence of salt solution freeze-thaw cycle on the crack resistance of asphalt mixture is greater than that of water solution freeze-thaw cycle according to horizontal strain-time curves. Compared with SBS modified asphalt mixture, the crack resistance of CR modified asphalt mixture is better. The conclusions obtained show that the analysis results of DSCT are consistent with the analysis results of fracture toughness tests, and indicates that it is feasible to evaluate the crack resistance of asphalt mixture adopting DSCT.