Analysis of Rutting Behaviour of Recycled Asphalt Binder and Rejuvenated Recycled Asphalt Binder by Multiple Stress Creep Recovery (MSCR) Test

Abstract

Abstract Due to its environmental and economic advantages, recycled asphalt pavement (RAP) is increasingly used in pavement construction. However, incorporating RAP into asphalt mixtures poses several challenges, primarily related to altering the rheological properties of the resulting asphalt binder. The small oscillatory shear test provides valuable insights into the viscoelastic characteristics of asphalt binders, which are crucial for determining whether the modified binders are suitable for pavement construction. RAP-modified asphalt binders' rheological properties significantly impact pavement structures' performance, including resistance to rutting, fatigue life, and crack resistance. Various rheological parameters of bitumen, such as complex modulus, phase angle, rate of recovery, and fatigue life, are utilized to predict the performance of modified bitumen. In our study, we employed a dynamic shear rheometer (DSR) to conduct performance grading (PG) tests and multiple stress creep recovery (MSCR) tests on VG40 virgin asphalt and RAP-modified binder at dosages of 35% and 50% for both RTFO-aged and unaged conditions at 60°C. A commercially available rejuvenator was used to address the stiffness of RAP-modified binders. We calculated MSCR parameters, including percentage recovery, non-recoverable creep compliance, and their percentage difference at stress levels of 0.1 kPa and 3.2 kPa, respectively. The results indicate a better recovery rate for RAP-modified and aged binders, suggesting improved resistance to rutting and enhanced performance under design traffic loading (ESAL). This study underscores the impact of rejuvenator oil on RAP-modified binders as pavement materials and explores the potential for using higher RAP dosages.