Effect of Aging on Fatigue Cracking of Asphalt Mixture Based on Digital Speckle Correlation Method

To study the effects of aging on the fatigue properties of warm-mixed crumb rubber asphalt mixture (WMA) and hot-mixed crumb rubber asphalt mixture (HMA), a three-point bending fatigue test was carried out on semi-circular WMA and HMA specimens. With the images collection through Digital image correlation method (DSCM) and calculation average horizontal strain ε_xa, the effect of aging on fatigue cracking was studied by the curve of ε_xa with cyclic loading times N. Results show that ε_xa can be adopted to study the fatigue cracking characteristics of asphalt mixture and the fatigue crack create when ε_xa plunges. Before the peak strain, the curve of unaged HMA and WMA was linear with N, while the curve was concave after aging. After aging, the anti-deformation ability of HMA and WMA was enhanced, and the anti-cracking performance became worse. WMA has better anti-cracking performance than that of HMA. As the aging degree increases, the main fatigue cracking forms of HMA and WMA change from viscoelastic destroy to brittle destroy.