Aging during construction and in-service substantially changes the chemical composition and physical properties of bitumen thereof influences the performance of asphalt pavements. The modification of bitumen by crumb rubber modifier (CRM) significantly increases the complexity of the aging mechanism and is expected to improve the aging resistance of bitumen. This study aims to investigate the effects of laboratory short-term and long-term aging on the chemistry and rheology of crumb rubber modified bitumen (CRMB). Neat bitumen and CRMB with four different CRM contents were studied. Fourier transform infrared spectroscopy and dynamic shear rheometer were employed to measure the change in the chemical composition and rheological properties of binders at different aging states. Bitumen hardening, which was rheologically revealed by the frequency sweep and multiple creep recovery test results, was also reflected in the growth of carbonyl and sulfoxide functional groups. In addition, the aliphaticity and aromaticity indices of binders before and after aging were also investigated. CRMB binders showed improved aging resistance compared to neat bitumen as reflected by the decreased carbonyl and sulfoxide indices as well as the lower change in rheological parameters. Higher resistance against aging was achieved when increasing the CRM content. The results also highlight the correlation between chemistry and rheology of bitumen. Among six selected mechanical parameters of binder, the non-recoverable creep compliance and percent recovery show better correlations with the combined chemical aging index (sum of carbonyl and sulfoxide indices) than the parameters derived from the linear viscoelastic region.

中文翻译：

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实验室老化对橡胶粉改性沥青化学和流变学的影响

施工和使用过程中的老化会显着改变沥青的化学成分和物理特性，从而影响沥青路面的性能。橡胶粉改性剂（CRM）对沥青的改性显着增加了老化机制的复杂性，有望提高沥青的抗老化性。本研究旨在研究实验室短期和长期老化对胶粒改性沥青 (CRMB) 化学和流变学的影响。研究了具有四种不同 CRM 含量的纯沥青和 CRMB。采用傅里叶变换红外光谱和动态剪切流变仪测量不同老化状态下粘合剂化学成分和流变性能的变化。沥青硬化，频率扫描和多次蠕变恢复测试结果在流变学上揭示了这一点，也反映在羰基和亚砜官能团的增长中。此外，还研究了老化前后粘合剂的脂肪性和芳香性指数。与纯沥青相比，CRMB 粘合剂显示出更好的抗老化性，这体现在羰基和亚砜指数的降低以及流变参数的变化较小。当增加 CRM 含量时，实现了更高的抗老化性。结果还突出了沥青的化学和流变学之间的相关性。在选定的 6 个粘结剂力学参数中，