Characteristics of interface cracking for ultraviolet aged hot-mix asphalt based on digital speckle correlation method

The digital speckle correlation method(DSCM) was taken to conduct a mesoscopic-level characterization on crack initiation and propagation patterns in semi-circular shaped hot-mix asphalt(HMA) specimens that were aged by ultraviolet lights and under tension-bending test. Vic-3D analysis software was employed to calculate the whole field displacement and strain, and displacement and strain fields of specimen rapturing process were obtained. The results show that, based on the comparison among asphalt mortar under ultraviolent lights, aggregate and the strain field along horizontal direction, the interphase is the weakest part of the hot-mix asphalt and it is more prone to producing crack. Further analysis of curve of strain along horizontal direction changing with load on HMA cracking time better reveals the time difference in initiating HMA micro-cracks and macro-cracks, and ultraviolet aging can noticeably shorten the interface initiating cracks time in HMA specimens. At the same time, upon receiving same ultraviolet aging, crumb rubber(CR) modified HMA has better cracking resistance and load-bearing capacity than styrene butadiene styrene(SBS) modified HMA based on comparing the patterns of load changing with displacement between CR modified HMA and SBS modified HMA specimens.