Cracking Resistance of Hot-Mix Asphalt Mixtures Containing Terminal Blend Rubberized Asphalt Nanocomposite at Intermediate Temperature

There is a general trend toward improving the terminal blend process of producing rubberized asphalt mixtures. Recently, the addition of nanosized materials to strengthen the performance-related properties of terminal blend rubberized asphalt (TBRA) has gained popularity. In this study, the TBRAs were prepared using 8% and 15% crumb rubber and then modified using 2% and 4% of an organophilic nanoclay. The structures of the TBRA nanocomposite were evaluated by X-ray diffraction and scanning electron microscopy. Conventional physical properties, storage stability, rheological properties, and aging resistance were also assessed. Furthermore, the Glover-Rowe (G-R) cracking parameter for each asphalt binder was determined from the rheological properties. Finally, the semicircular bending test was implemented to determine J-integral ($J_C$) and flexibility index (FI) parameters and characterize the cracking resistance of TBRA and TBRA nanocomposite mixtures. The results indicate that the use of the TBRA and its modification by nanoclay leads to an increase in asphalt mixture cracking resistance during the initiation cracking phase but increases the asphalt mixture’s brittleness during the crack propagation phase. There was a significant correlation between the G-R parameter for the asphalt binders and the FI parameters of the respective TBRA mixtures. Moreover, it was observed that TBRA modification by an organophilic nanoclay decreased the temperature susceptibility and phase separation, increased the viscosity, penetration, softening point, aging resistance, and elasticity, and improved high-temperature performance.