Fatigue and self-healing analyses of bituminous binders modified with a recycled plastic compound

In recent years, the asphalt industry has focused on improving pavement performance and durability while adopting more sustainable construction practices. Recycled plastic materials have become increasingly relevant for achieving these goals, as they can enhance material properties and reduce environmental impact. However, the direct use of recycled plastics in binder modification—especially those originally designed for hybrid or dry modification methods—is still not widely explored. This thesis investigates the fatigue and self-healing behaviour of bituminous binders modified with Recycled Low-Density Plastic (RLDP). Two modified binders containing 2% and 4% RLDP by total binder mass were tested, along with a neat 50/70 penetration grade binder used as a reference. The Dynamic Shear Rheometer (DSR) was employed to evaluate fatigue and healing performance through Frequency Sweep (FS), Linear Amplitude Sweep (LAS), and LAS-Healing (LASH) tests. The results showed that RLDP addition increased binder stiffness and elasticity while maintaining thermorheological consistency. The 4% RLDP binder demonstrated better resistance to fatigue damage, whereas the 2% RLDP binder showed higher self-healing efficiency, recovering more stiffness after rest periods due to greater molecular mobility. Overall, the study confirms that recycled plastic modification, especially at moderate dosages, can enhance both fatigue resistance and self-healing capacity of bituminous binders, offering a practical and sustainable alternative to traditional polymer modification in pavement engineering.