Cold Patching Asphalt Mixture with Cutback and 100% Reclaimed Asphalt Pavement: Interfacial Diffusion Mechanism and Performances Evaluation

Potholes are one of the common diseases of asphalt pavements. Cold patching asphalt mixtures (CPAM) are a common material for pothole repair. Reclaimed asphalt pavement (RAP) is a high-potential sustainable material that is commonly used in pavement construction. The aim of this study is to address the balance between performance improvement and cost reduction in CPAM. To achieve this objective, the CPAM was prepared with four different contents of cutback and 100% RAP (RAP-CPAM) and its performances were evaluated by laboratory tests. First, Fourier transform infrared spectroscopy (FTIR) test and scanning electron microscope (SEM) technique were used to analyze the diffusion mechanism between the cutback and the artificial aged binder. Then, the rationality of the cutback content was preliminary estimated by the mixing test and the draindown test. Finally, the adhesion performance, cohesion performance, strength, and resistance to water damage of RAP-CPAM were characterized through laboratory tests. From the FTIR test, the carbonyl index of aged asphalt layer decreased compared to that of the artificial aged binder as the storage time increased. Simultaneously, SEM imaging of the artificial aged binder showed less fractured surfaces after storage. The results of FTIR and SEM tests indicate that the cutback and the artificial aged binder were diffused. It was found that 1.6% content of cutback was slightly lower for RAP-CPAM, and 2.8% was not excessive. Boiling test results show that RAP-CPAM had good adhesion performance. Rolling screen test, Marshall stability test, and immersion Marshall test results reveal that RAP-CPAM had good cohesion performance, strength, and resistance to water damage. Based on the performance evaluation, the optimal content of cutback in RAP-CPAM was determined as about 2.4%–2.8%. In conclusion, the cutback and the RAP binder were successfully diffused, thereby ensuring good performances of RAP-CPAM.