Aging behavior characteristics of LDPE-SBS composite modified asphalt binder: A study of plasto-elastomeric composite

Asphalt undergoes aging throughout its lifespan, leading to cracking, reduced performance, and ultimately premature failure. Polymers as single or composites are used to modify asphalt binders, giving a promising concept for boosting its properties across various performance domains. However, a thorough evaluation of aging behavior for composite modifications of asphalt binders is still pending. This study investigates the efficacy of single and composite modification of asphalt binders, using plastomeric waste low density polyethylene (LDPE) and elastomeric styrene butadiene styrene (SBS) polymers, to delay aging in binders under different aging conditions. Aging was done in the laboratory using a thin film oven for short-term aging and a pressure aging vessel for long-term aging. The flow changes were assessed through softening point and rotational viscosity tests, while as rheological changes were evaluated from complex shear modulus (G*), phase angle (delta), Multiple Stress Creep Recovery (MSCR), Zero Shear Viscosity (ZSV) and Linear Amplitude Sweep (LAS) parameters using a Dynamic Shear Rheometer (DSR) apparatus. Fourier transform infrared spectroscopy (FTIR) was used to determine chemical changes. Furthermore, the microstructural analysis of samples was performed by optical microscopy. The comparison of aging indices indicates that composite modified asphalt binders demonstrate significant improvement in aging resistance, high resistance towards permanent deformation and better elastic behaviour at higher temperatures. The correlation analysis between various indices showed good interrelationships. The results of the study encourage the utilization and reuse of waste LDPE in flexible road pavements by improving and maintaining its performance.