Edge cracked semi‐circular shape specimen subjected to three point bend loading is a favourite test specimen for determining fracture toughness of asphalt mixtures. However, in the vast majority of previous experimental works, the homogeneous medium assumption has been considered for determining the stress intensity factor and geometry factors of asphalt mixtures tested with this test configuration. As a more realistic model and in order to consider the effects of heterogeneity on corresponding values of stress intensity factors, the asphalt mixture was modelled as a two‐phase aggregate/mastic heterogeneous mixture and its fracture behaviour was investigated using numerical models of asymmetric semi‐circular bend (ASCB) specimens. The generation and packing algorithm was employed to randomly distribute the aggregates with different shapes and sizes inside the mastic part. The effect of the mechanical properties of asphalt mixture (elastic modulus and the Poisson's ratios of aggregates and mastic), coarse aggregates distribution and crack length were studied on modes I and II geometry factors by means of extensive two‐dimensional finite element analyses. Moreover, the effect of the elastic modulus of asphalt mixture components was evaluated on the fracture path using the maximum tangential stress criterion. It was shown that crack tip location, elastic modulus of aggregates and mastic are the most important affecting parameters on the magnitude of modes I and II geometry factors. It was also shown that the geometry factors are not sensitive to the Poisson's ratios of aggregates and mastic. In addition, fracture cracking path is affected by the elastic modulus of the asphalt mixture components such that, depending on the difference between the stiffness of stiffer coarse aggregates and softer mastic part, the crack may propagate either through the aggregates, mastic or interface of aggregate/mastic.

中文翻译：

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异质性对SCB试样形状的实验室沥青混合料I / II混合应力强度因子和断裂路径的影响

受到三点弯曲载荷作用的边缘开裂的半圆形试样是确定沥青混合料断裂韧性的常用试样。但是，在绝大多数先前的实验工作中，均已考虑使用均质介质假设来确定使用此测试配置测试的沥青混合料的应力强度因子和几何因子。作为一个更现实的模型，并且考虑到不均匀性对应力强度因子的相应值的影响，将沥青混合料建模为两相骨料/胶体非均质混合料，并使用不对称半混凝土的数值模型研究了其断裂行为。圆形弯曲（ASCB）标本。生成和堆积算法被用来在乳胶部分内部随机分布具有不同形状和大小的聚集体。通过广泛的二维有限元分析，研究了模式I和II的几何因素对沥青混合料机械性能（弹性模量和骨料与乳胶的泊松比），粗骨料分布和裂纹长度的影响。此外，使用最大切向应力准则评估了沥青混合料组分弹性模量对断裂路径的影响。结果表明，裂纹尖端的位置，骨料的弹性模量和胶泥是影响模态I和II的几何因子大小的最重要的影响参数。研究还表明，几何因素对泊松方程不敏感。的骨料和乳香的比例。此外，裂缝的开裂路径受沥青混合料组分的弹性模量的影响，因此，取决于较硬的粗骨料和较软的乳胶部分的刚度之间的差异，裂纹可通过骨料，胶泥或骨料的界面传播/乳香。