Abstract Cracked pavements can be subjected to out-of-plane sliding or mode III deformation due to movement of vehicles. In order to design suitable asphalt mixture for manufacturing high resistance pavements against mode III failure, it is necessary to determine a characteristic parameter called mode III fracture toughness (KIIIc) for these materials. In this research a comprehensive experimental study is performed to obtain the value of (KIIIc) for hot mix asphalt (HMA) mixtures under different geometrical and testing conditions. An edge notch disc bend specimen was utilized for conducting the mode III fracture toughness experiments on HMA mixture at low temperature conditions. Several discs with three thicknesses were cut from HMA mixtures made by gyratory compactor machine and with different air voids. The experiments showed that by increasing the size of test specimen, mode III fracture toughness can increase significantly. Furthermore, KIIIc value is increased by decreasing the test temperature from 0 °C to −24 °C and decreasing the air void content from 7% to 3%. A regression analysis was implemented on the test results and it was found that the thickness and air void have the maximum and minimum influences on KIIIc value, respectively. In addition, it was shown that the mode III fracture toughness of tested asphalt mixture is noticeably less than the corresponding value of the same mixture tested under mode I condition with the same testing conditions. The fracture toughness ratio (KIIIc/KIc) that was varied from 0.5 to 0.7 for different testing conditions and specimen sizes was predicted theoretically using some stress/strain based fracture criteria.

中文翻译：

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面外滑模下热拌沥青混合料抗裂性能研究

摘要 开裂的路面会因车辆的移动而产生面外滑动或III 型变形。为了设计合适的沥青混合料来制造抗 III 型破坏的高阻力路面，有必要确定这些材料的称为 III 型断裂韧性 (KIIIc) 的特征参数。在这项研究中，进行了一项全面的实验研究，以获得不同几何和测试条件下热拌沥青 (HMA) 混合物的 (KIIIc) 值。边缘缺口圆盘弯曲试样用于在低温条件下对 HMA 混合物进行 III 型断裂韧性实验。从由旋转压实机制成的具有不同气孔的 HMA 混合物中切割出几个具有三种厚度的圆盘。实验表明，通过增加试件尺寸，III型断裂韧性可以显着提高。此外，通过将测试温度从 0 °C 降低到 -24 °C 并将空隙率从 7% 降低到 3%，KIIIc 值会增加。对测试结果进行回归分析，发现厚度和空隙分别对KIIIc值的影响最大和最小。此外，试验表明，在相同试验条件下，试验沥青混合料的模式Ⅲ断裂韧度明显小于模式Ⅰ条件下试验的相同混合料的相应值。断裂韧性比 (KIIIc/KIc) 从 0.5 到 0 变化。