Modeling Influence of Aging and Rejuvenation Mechanisms on the Recycled Asphalt Pavement (RAP) Binder Fatigue Life through the Linear Amplitude Sweep Test

Although the influence of the load or strain level on binder fatigue has been comprehensively studied, modeling the effects of oxidative aging remains a challenging task. This study initially explores the rejuvenation mechanism of aged binders using physicochemical and rheological tests in different aging conditions. Then, the effects of aging on the fatigue life parameters in the LAS method for rejuvenated RAP binders are investigated concerning alterations in complex modulus. Finally, a fatigue life model for predicting Nf of rejuvenated RAP binders under varying aging conditions is developed, using LAS testing and complex modulus data. According to the results, the sulfoxide index and aromatic fraction illustrated the dominant rejuvenation efficacy of 10% waste cooking oil (WCO) in aged binder blends. This finding resulted in an enhancement of the fatigue performance of RAP binders. Moreover, fatigue damage parameters, including A and B, exhibit linear correlations with complex modulus (G*) at different aging levels. The proposed fatigue life (Nf) model, considering aging effects and strain levels, offers a more reliable and simpler approach in predicting Nf under different aging conditions based on both the maximum stress failure criteria and 35% damage level. This model can predict Nf over a wider range of strain levels and aging conditions for rejuvenated RAP and base binders from the LAS test procedure.