Evaluating the Performance of Asphalt Concrete Supplemented with Various PET Types

The rapid utilization of non-renewable natural aggregates, bitumen, lime, and cement in construction for road pavement development and repair is unsustainable due to excessive solid waste production and inefficient disposal methods. To address this issue, researchers are exploring alternative materials derived from these wastes for road construction and maintenance. With the escalating costs of polymers and increasing plastic waste, a focus has shifted towards developing pavements using waste plastics. This study assesses the advantages of incorporating recycled (PET-Type 2) and virgin (PET-Type 1) polyethylene terephthalate polymers into 40/50 penetration grade bitumen using a common bitumen modification technique. In this study, the Marshall mix design method was used to create standard asphalt mixtures. The aim is to investigate how the addition of PET polymers impacts the performance of asphalt pavement. Furthermore, the objective is to determine the optimum proportions of two PET types and their influence on the performance of compacted asphalt paving materials for highways, utilizing Marshall properties and indirect tensile strength. Various concentrations of asphalt modifiers, ranging from 1 to 4 wt % of bitumen, were tested to gauge their effects on asphalt performance under high-temperature conditions. Laboratory experiments were conducted to analyze the physical properties of both unmodified and modified asphalt mixtures. Results indicate that incorporating 2% PET-Type 1 and 3% PET-Type 2, based on bitumen weight, into asphalt mixtures improved stability by 36.3%, and 29.5%, respectively. Additionally, the tensile strength and TSR value indicate sufficient resistance to moisture. The SEM analysis indicates that including modifiers led to a more uniform bitumen composition, resulting in improved cohesion and mechanical properties. Consequently, the characteristics of the asphalt mixture were enhanced. FTIR analysis demonstrates that test results can be used to predict the rheological properties of asphalt and examine the chemical bonds or functional groups found in pure and altered asphalt binders. The addition of PET-Type 1 led to the formation of a new absorbance peak corresponding to the C‒O bond, whereas the alteration with PET-Type 2 produced a peak corresponding to the C‒H bond.