## 3 Tests and Methodology
### Laboratory Physical Clogging Procedure
#### 3.2.2 Experimental Procedure  
In this paper, a dynamic water scouring application device (SAD) was used to apply various dynamic water scouring intensities on to the paver surface. The purpose of the SAD was to simulate in-field scenarios of dynamic scouring of surface runoff and to adequately mobilize clogging materials over the paver surface. In order to meet the above requirement, dynamic water scouring intensities were simulated using a high-pressure water gun. The high-pressure water gun was attached to a custom frame and a 100 mm polyvinyl chloride pipe which was connected to the water mains, as shown in Figure 4. In order to simulate the speed of the vehicle, four cylindrical steel structures without a top surface were fixed on a custom frame, while the rotation speed of the cylindrical structures could be controlled through the motor. The cylindrical structure with hole diameters of 2 mm had a diameter \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Number** & **Region** & **Pavement Grade** & **Location** & **Pavement Type** \\ \hline
1 & & Heavy-duty road & Renmin Street & Asphalt pavement \\
2 & Urban area & Heavy-duty road & Yatai Street & Asphalt pavement \\
3 & & Non-overloaded road & Wenchang Street & Asphalt pavement \\
4 & & Non-overloaded road & Nanjing Community & Concrete pavement \\ \hline
5 & & Heavy-duty road & Xincheng Street & Asphalt pavement \\
6 & Suburban area & Heavy-duty road & Fuzhi Street & Asphalt pavement \\
7 & & Non-overloaded road & Yinxing Street & Asphalt pavement \\
8 & & Non-overloaded road & Langtian Community & Concrete pavement \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Clogging materials collection locations. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Particle Size Range (\(\mu\)m)** & **Mesh Hole Number (n)** & **Granularity Attribute** \\ \hline
2360–4750 & 4 & Fine gravel \\
1180–2360 & 8 & Very coarse sand \\
600–1180 & 16 & Coarse sand \\
300–600 & 30 & Medium sand \\
150–300 & 50 & Fine sand \\
75–150 & 100 & Very fine sand \\ \(<\)75 & 200 & Silt \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Particle size score table of clogging materials. of 102 mm and a height of 65 mm, which guarantees that a Marshall test piece can be contained, and the water flow can be discharged smoothly through the holes. In order to establish the connection between the laboratory dynamic water scouring application device and the actual condition of the pavement, a piezoresistive dynamic water pressure sensor was embedded in the Hui-wu expressway (in Songyuan, Jilin, China) to collect the dynamic water scouring pressure of the pavement. The collected water scouring pressure data are shown in Figure 5.  
According to the collected data, adjusting the pressure of the water gun and the rotation speed of the cylindrical structure to realize the laboratory scouring test, the corresponding relationship between the vehicle, water gun pressure, and the rotation speed of the cylindrical structure is shown in Table 8.  
The details of the physical clogging procedure are described below. Step 1: Marshall specimens were prepared by the compaction method according to T 0702, and the side of the specimens was coated with butter and wrapped with a plastic film. Figure 4: Dynamic water scouring application device. Figure 5: The variation of scouring pressure with time at different speeds. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Speed of Vehicle (km/h)**} & **In-Field Measured** & **Water Gun** & **Rotation Speed of Cylindrical** \\  & **Pressure (KPa)** & **Pressure (KPa)** & **Structure (rad/min)** \\ \hline
40 & 161.351 & 1201.3 & 210 \\
60 & 209.692 & 1863.4 & 300 \\
80 & 324.24 & 2561.6 & 420 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Corresponding relationship between vehicle and water gun pressure and the rotation speed of the cylindrical structure.