Asphalt concrete is composed of stone, sand, filler, and asphalt binder. Fatigue can be considered as a phenomenon affecting both the binder (asphalt binder or mastic) and the mixture. The purpose of this study was to investigate the fatigue damage response in asphalt binders, mastics, and asphalt concrete mixtures modified with nano-silica and synthesized polyurethane. The continuum damage mechanics method and phenomenological approaches in this study were used to investigate the fatigue performance. Obtained results indicated that the effect of the synthesized polyurethane on improving the fatigue life was far greater than that of nano-silica. The damage process in asphalt binders differed from that in the mastic and asphalt concrete mixture. Damage intensity parameter is an appropriate criterion for evaluating fatigue performance of asphalt binders and mastics. Concerning the fatigue of asphalt concrete mixture, the results of this study indicated a better convergence between the fatigue parameters of mastics and asphalt concrete mixture compared to asphalt binders, especially with increasing aging. Also, there was greater convergence between the fatigue life of the asphalt concrete mixture and asphalt binder and mastics in the method of continuum damage mechanics as compared to the phenomenological approach.

中文翻译：

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纳米二氧化硅与合成聚氨酯改性沥青结合料、胶粘剂和沥青混凝土混合料的疲劳响应

沥青混凝土由石头、沙子、填料和沥青粘合剂组成。疲劳可以被认为是影响粘合剂（沥青粘合剂或乳香）和混合物的现象。本研究的目的是研究用纳米二氧化硅和合成聚氨酯改性的沥青结合料、胶粘剂和沥青混凝土混合物的疲劳损伤响应。本研究中的连续介质损伤力学方法和现象学方法用于研究疲劳性能。所得结果表明，合成聚氨酯对提高疲劳寿命的作用远大于纳米二氧化硅。沥青结合料的损伤过程不同于胶泥和沥青混凝土混合物中的损伤过程。损伤强度参数是评价沥青结合料和胶粘剂疲劳性能的合适标准。关于沥青混凝土混合料的疲劳，本研究的结果表明，与沥青结合料相比，胶粘剂和沥青混凝土混合料的疲劳参数之间有更好的收敛性，尤其是随着老化的增加。此外，与现象学方法相比，连续损伤力学方法中沥青混凝土混合物和沥青结合料和胶泥的疲劳寿命之间存在更大的收敛性。