Experimental characterization of the oxidative kinetic aging behavior of rejuvenated asphalt binder

Abstract

• Rejuvenated binders were subjected to over-aging at various temperature and time. • The effect of temperature, duration and rejuvenator dosage on the oxidative aging mechanisms of rejuvenated binders were revealed. • Oxidative aging increased the viscoelastic behavior of rejuvenated binders while rejuvenator reduced. • The effect of rejuvenator on viscoelastic behavior of rejuvenated binders weakened gradually during oxidative aging. Rejuvenator is commonly used in reclaimed asphalt pavement (RAP) to improve the properties of the blended binder. However, the rejuvenated binder would experience aging again and cause the rejuvenated asphalt mixture prone to durability issues. This study focused on evaluating the impact of oxidative aging on the chemical and rheological properties of rejuvenated binder (RB) by means of Fourier Transform Infrared Spectroscopy and Dynamic Shear Rheometer. First, the aged binders blended with waste engine oil used as the rejuvenator at 0%, 3%, 6%, and 9% by total weight of binder. Then, laboratory oven aging procedures were employed to the RB binders at different aging temperatures and periods. Carbonyl content were determined to understand the effect of temperature and duration on the oxidative aging mechanisms of RB binders. Each RB binder had its specific fast and constant oxidative rates. With the increase of rejuvenator dosage, the temperature sensitivity of RB binders decreased in the constant rate stage and increased in the fast rate stage. The high-temperature true performance grade (HTPG) of RB binders increased with the aging time and temperature, and the effect of rejuvenator dosage on HTPG decreased gradually with aging duration. Based on the master curves of complex modulus and phase angle, the aging time and aging temperature increased the viscoelastic behavior of RB binders, and rejuvenator reduced the viscoelastic behavior, but the effect of rejuvenator lowered gradually during oxidative aging. The crossover frequency, rheological index and Cole-Cole plot demonstrated the aging decreased the viscous components and increased the elastic behavior of the RB binders. As the rejuvenator dosage increased, the viscous component of the aged RB binders increased, and the elastic behavior decreased as well as more transition behavior from viscous to elastic.