## Materials and Methods
### Methods  
#### 2.2.1 Sample Preparation  
In this study, all modified asphalt samples were prepared using both the mechanical and high-shear mixers. Before the modification process, 1000 g of neat asphalt was heated to 175 \({}^{\circ}\)C and the viscosity of the original bitumen (135 \({}^{\circ}\)C) was checked; it was about 0.411 Pa. s [20]. The various mass concentrations of CRM, PP, and TPS had percentages of 2, 3, 3.5, and 4%, respectively, by weight of the asphalt binder. These were added progressively to the neat asphalt binder for 1 h. The mixing speed was 1600 rpm and was conducted with a propeller mixer. Then, the prepared bitumen was transferred to a high-speed mixer at a rate of 2500 RPM and with a constant temperature of \(185\pm 5\)\({}^{\circ}\)C for a duration of 2 h [13; 21].  
To prepare the sample for the ductility test, the modified asphalt was heated to \(163\pm 5\)\({}^{\circ}\)C while mixing and then poured in the mold assembly and placed on a brass plate. To prevent the material under test from sticking the surface of the plate and interior surfaces of the sides of the mold were coated by a mixture of equal parts of glycerin and dextrin. The plate assembly along with the sample was kept in a water bath for about 30-40 min. The temperature of the water bath was 25 \({}^{\circ}\)C for half an hour. The sample and mold assembly were removed from the water bath and the specimen was trimmed by levelling its surface using a hot knife. The mold assembly was kept in a water bath for 85 to 95 min according to American Society for Testing and Materials (ASTM D113) [9].  
In the rotational viscosity test sample preparation, the modified asphalt was heated with continued stirring until a consistent binder temperature of 190 \({}^{\circ}\)C was achieved. Further, 10 g was then poured into the container. The actual test temperature was 135 \({}^{\circ}\)C and recorded with the corresponding viscosity measurement (ASTM D2170).  
When preparing the DSR test sample, 0.6 g of the specimen was sandwiched between two plates with a diameter of 25 mm with a 1 mm gap.  
To conduct the toughness and tenacity test, the test specimens were heated to 150 \({}^{\circ}\)C for 90 min. Then, 90 mL was poured into the container with nominal inside dimensions of 55 mm in diameter and 35 mm in depth. Next, the mixture was carefully lowered into the tension head using the knurled  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Item** & **Properties** \\ \hline Shape & Granular (3–4 mm) \\ Density (g/cm\({}^{3}\)) & 0.895–0.92 \\ Melting point (\({}^{\circ}\)C) & \(>\)190 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Physical properties of polypropylene (PP).  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Item** & **Properties** \\ \hline Shape & Granular (2–3 mm) \\ Color & Yellow \\ Relative density (\%) & 0.98 \\ Weight per volume & 0.6 ton/m\({}^{3}\) \\ \hline \hline \end{tabular}
\end{table}
Table 3: Physical properties of fatpack super (TPS).  
screws until immersed in the sample to a depth of exactly 11 mm in the center of the specimen. The container and head were cooled at an ambient laboratory temperature for 60 min, then placed in a water bath that was maintained at 25 \({}^{\circ}\)C. After 60 min, the specimen was removed from the water bath and immediately placed in the testing machine in which all charts, gears, and other parts were prepared and calibrated [4]. Figure 1 illustrates the toughness and tenacity experimental setup and test instruments.  
Figure 1: Apparatus for the toughness and tenacity test: (**a**) Tension head and spider; (**b**) proper position of tension head in asphalt sample; (**c**) testing machine; (**d**) asphalt sample under pulling force; and (**e**) chart for calculating toughness and tenacity.