The objective of this study was to qualitatively measure the cracking mechanism of asphalt-rubber gap-graded (AR-Gap) mixtures and compare the methodical approach proposed in this research with the conventional fatigue process. As part of experimentation plan, dynamic a semi-circular bending (SCB) test was conducted on 27 AR-Gap mixtures with varying mix parameters, including, binder type, binder content, and aggregate gradation. Fatigue life (N_f) obtained from the dynamic SCB test was analyzed from a statistical viewpoint, and key relationships that potentially contribute to fatigue performance were identified. Later, crack mouth opening displacement (CMOD) was used to study the cracking mechanism of AR-Gap mixtures. CMOD data were analyzed using the Francken model that theorizes the accumulated damage as a three-stage failure. Further, fatigue tertiary life (N_ft) was determined on the premise of structural deterioration obtained from the three-stage failure process. The fatigue disparity factor (ξ), the ratio of N_f to N_ft for each asphalt mix was estimated to compare fatigue performance indices. The score of ξ for all the mixtures exceeded 50%, which was indicative of longer crack initiation and crack propagation phase over the third stage of the fatigue cracking mechanism. Overall, the fatigue mechanism was explained through the conceptualization of the three-stage fatigue process through various intrinsic properties of AR-Gap mixtures.

这项研究的目的是定性地测量沥青-橡胶间隙梯度（AR-Gap）混合物的开裂机理，并将本研究提出的方法与常规疲劳过程进行比较。作为实验计划的一部分，对27种AR-Gap混合物进行了动态半圆弯曲（SCB）测试，混合物具有不同的混合参数，包括粘合剂类型，粘合剂含量和骨料级配。疲劳寿命（Ñ _˚F从统计角度分析了从动态SCB测试获得的），并确定了可能导致疲劳性能的关键关系。后来，用裂口张开位移（CMOD）研究了AR-Gap混合物的裂化机理。使用Franken模型对CMOD数据进行了分析，该模型将累积的损坏理论化为三阶段故障。此外，在从三阶段破坏过程获得的结构劣化的前提下确定疲劳第三寿命（N _ft）。疲劳差异因子（ξ），N _f与N _ft之比估计每种沥青混合料的疲劳性能指标。所有混合物的ξ得分均超过50％，这表明在疲劳裂纹机理的第三阶段，裂纹萌生和裂纹扩展阶段更长。总体而言，通过AR-Gap混合物的各种固有特性，通过三阶段疲劳过程的概念化解释了疲劳机理。