## 3 Methods for Incorporating Waste Plastics into Asphalt Pavements  
The incorporation of waste plastics into asphalt pavement can be accomplished through several techniques, including the wet method, dry method, and a hybrid referred to as the mixed method. In the wet method, plastic waste is melted and incorporated directly into the heated asphalt binder at elevated temperatures (often 160 \({}^{\circ}\)C-180 \({}^{\circ}\)C), employing high-shear mixing to attain uniformity. This technique enhances the interaction between plastic and binder, resulting in superior elastic recovery and rutting resistance; however, it necessitates specialized equipment and presents issues such as phase separation and inadequate storage stability at elevated temperatures [10; 11; 28; 30]. \begin{table}
\begin{tabular}{p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline \hline
**References** & **Plastic Type** & **Density (g/cm\({}^{3}\))** & **Melting Point (\({}^{\circ}\)C)** & **Common Waste Sources** & **Key Advantages** & **Key Disadvantages** \\ \hline
[11; 14; 27; 31] & LDPE & 0.91–0.94 & 110–120 & Bottles, packaging films, bags & Good compatibility, flexibility, easy processing & UV degradation, lower strength \\ \hline
[11; 14; 31; 32] & HDPE & 0.94–0.97 & \(\sim\)130 & Containers, pipelines, industrial packaging & Elevated strength, moisture resistance & Fragile at low temperatures \\ \hline
[10; 11; 28] & PP & 0.90–0.91 & 145–165 & Straws, furnishings, automotive parts & Straws, automotive parts & superior chemical pressures high-temp performance & Inadequ adhesion with bitumen unless compatibilized \\ \hline
[11; 14; 27] & PVC & 1.34–1.39 & 160–210 (decomposes) & Pipes, cables, window frames & Flame resistance, stiffness & Releases toxic gases (e.g., HCl), poor thermal cracking resistance \\ \hline
[10; 11] & PS & 1.04–1.07 & 210–249 & Food containers, cutlery, CD cases & Elevated rigidity, enhanced rutting resistance & Extremely brittle, poor low-temp performance \\ \hline
[9; 11; 14; 27] & PET & 1.16–1.58 & \(\sim\)260 & Beverage containers, fabrics & High tensile strength, chemical resistance & Requires substantial energy to melt, brittle at low temperatures \\ \hline
[11; 14; 33] & EVA & 0.93–0.95 & 65–80 & Sole materials, films, cables & Elastomeric properties, good low-temp performance & High viscosity, phase separation risks above 2 wt\% \\ \hline
[11; 27] & rABS & 1.03–1.07 & No true melting pt & E-waste, electronics & Improves viscosity and thermal characteristics & Limited compatibility, minimal minimal microcyclability \\ \hline
[11; 28] & PU & 1.2–1.3 & No true melting pt & Upholstery, insulation, footwear & High strength & Decomposes, environmental risk when subjected to heating \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Characteristics, sources, and suitability of common waste plastics in asphalt pavement applications. In contrast, the dry method is the direct incorporation of solid plastic waste frequently in shredded, pelletized, flaked, or powdered form into the heated aggregates prior to the addition of the binder. This technique enables polymers to act as filler or reinforcement, coating aggregate surfaces without directly altering the binder. It is easier to apply in existing asphalt plants and requires less expenditure; however, it may lead to less uniform dispersion, diminished moisture resistance, and lower enhancement of binder properties compared to the wet method [11; 34]. An intermediate mixed method has been proposed, including elements of both wet and dry methods. This method involves pre-coating low-melting-point polymers onto heated aggregates, facilitating partial diffusion into the binder when added later. This approach enhances polymer distribution while minimizing dependence on specialized wet-process equipment. Nonetheless, it encounters obstacles like adjusting mixing temperature, assuring adequate plastic diffusion, and gaining consistency at scale [10; 11; 35].