ABSTRACT Asphalt pavements deteriorate over time due to the aging process that increases binder stiffness and brittleness and reduces performance and durability. Rejuvenators, particularly spray-on rejuvenators (SORs), offer an economical and easy-to-implement solution by restoring the maltenes-to-asphaltenes ratio and improving the flexibility of aged asphalt binders. This study focuses on evaluating the changes in stiffness and cracking resistance of asphalt concrete (AC) mixtures by interlaboratory testing of the modified bending beam rheometer (Mod-BBR) test and the circular bending test (CBT). A total of 104 specimens were tested using the Mod-BBR, and 39 specimens were evaluated using the CBT to assess the effectiveness of 12 SORs on an AC test section at the MnROAD test facility. The findings indicated that (i) SORs significantly influence the mechanical properties of AC mixtures and (ii) the performance of different SORs varied significantly, with some demonstrating substantial reduction in creep stiffness and improving fatigue resistance after 2 years of application, whereas others showed limited or no significant effect. In addition, an inverse correlation was observed between the creep stiffness and the fatigue resistance properties such as cracking tolerance index, flexibility index, and cracking resistance index, reinforcing the necessity to adjust the AC stiffness to enhance the durability of the pavements. The study emphasizes the critical importance of selecting suitable SORs and highlights the necessity of regular reapplications to ensure the sustained performance of pavement structures. Additionally, the testing methods showed reliability in evaluating the effectiveness of SOR treatments under different laboratory settings and conditions.
Islam et al. (Wed,) studied this question.