Thermo-rheological characteristics of unmodified and modified bitumen have significant impacts on the mechanical response of asphalt. This study investigates the impacts of an organic and a chemical Warm Mix Asphalt additive on bitumen thermo-rheological and mechanical characteristics. Modified binders with different concentrations of each additive were studied and analysed comparatively to a 40/60 penetration grade bitumen. Frequency sweep tests were performed at different ageing levels to characterise the Linear Viscoelastic properties. The multiple stress creep and recovery, linear amplitude sweep (LAS) and low temperature creep stiffness tests, together with the Glover–Rowe (G–R) fatigue parameter (determined from fitting of the 2S2P1D model to the complex shear modulus and phase angle master curves) were used to analyse the performance of the binders at critical operating temperatures. The results demonstrated the necessity to analyse the behavior of the studied binders beyond the limits of linear viscoelasticity to better characterise these types of bitumen. The results also indicated that both additives retarded bitumen ageing with the organic additive increasing bitumen elastic response while the chemical additive increased its viscous response. The results also showed an excellent correlation between the G–R parameter and LAS results which suggests the ability to use this parameter in characterising fatigue performance of the studied binders. This also suggests that bitumen fatigue life may be improving over time due to the increased elastic behahviour during ageing so long as a certain critical level of ageing is not reached.

中文翻译：

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WMA添加剂改性粘合剂的热流变分析

未改性和改性沥青的热流变特性对沥青的机械响应有显着影响。本研究调查了有机和化学温拌沥青添加剂对沥青热流变学和机械特性的影响。与 40/60 渗透等级的沥青相比，研究和分析了具有不同浓度的每种添加剂的改性粘合剂。在不同的老化水平下进行频率扫描测试以表征线性粘弹性。多重应力蠕变和恢复、线性振幅扫描 (LAS) 和低温蠕变刚度测试，连同 Glover-Rowe (G-R) 疲劳参数（通过将 2S2P1D 模型拟合到复杂的剪切模量和相角主曲线来确定）用于分析粘合剂在临界工作温度下的性能。结果表明有必要分析所研究的粘合剂超出线性粘弹性极限的行为，以更好地表征这些类型的沥青。结果还表明，两种添加剂都延缓了沥青老化，有机添加剂增加了沥青弹性响应，而化学添加剂增加了其粘性响应。结果还表明 G-R 参数与 LAS 结果之间具有极好的相关性，这表明可以使用该参数来表征所研究粘合剂的疲劳性能。