基于数字散斑相关方法的老化对沥青混合料疲劳开裂的影响

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

    • 摘要: 为研究老化作用对温拌胶粉改性沥青混合料(warm-mix rubber powder modified asphalt mixture,WMA)和热拌胶粉改性沥青混合料(hot-mix rubber powder modified asphalt mixture,HMA)疲劳性能的影响,对WMA和HMA的半圆试件进行三点弯曲疲劳试验.采用数字散斑相关方法(digital speckle correlation method,DSCM)对疲劳断裂的过程进行图像采集,并计算开裂过程中的平均水平应变εxa,通过εxa随循环荷载作用次数N的变化曲线研究老化作用对疲劳开裂的影响.结果表明:εxa适用于沥青混合料疲劳开裂的研究,裂缝在εxa突变时产生;未老化WMA和HMA的εxa-N曲线在达到峰值应变前,εxaN的增加基本呈线性增长趋势,老化后呈下凹式非线性增长趋势;老化作用后,HMA和WMA的抗变形能力增强,抗开裂性能变差,WMA的抗开裂性优于HMA;随老化水平增加,HMA和WMA的疲劳破坏形式逐渐由黏聚性占主导的黏弹性破坏转变为黏附性占主导的脆性破坏.

       

      Abstract: 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 εxa, the effect of aging on fatigue cracking was studied by the curve of εxa with cyclic loading times N. Results show that εxa can be adopted to study the fatigue cracking characteristics of asphalt mixture and the fatigue crack create when εxa 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.

       

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