## 3 Evaluation of PM\({}_{10}\) Generated in Cutting Operation through Chamber Experiment (Level 2)
### Methodology
#### 3.1.2 Experimental Method  
In this study, asphalt concrete specimen cutting activity was performed in four conditions, as shown in Table 4. The cutting length of all experiments was fixed at 800 mm. In the cases of the test identities (IDs) 1-3, the cutting depths were set to 50 mm, 70 mm, and 100 mm, respectively, to analyze the PM emission characteristics according to the cutting depth. In the cases of test IDs 3 and 4, the cutting depth and cutting length were set to be the same, and the PM emission characteristics according to the cutting conditions were analyzed by performing dry and wet cutting.  
PM generated from cutting activities were analyzed by dividing them into scattered and deposited PM. The scattered PM were analyzed by using the filter installed in the chamber and GRIMM's OPC. The OPC used in this experiment is the same equipment used in Section 2. The OPC calculated the mass concentration by measuring the number concentration and applying a correction factor considering the density of the particles to be measured. The correction factor was calculated by measuring the density of the particles collected in the low-volume sampler attached to the OPC [34].  
The deposited PM was analyzed by using the vacuum sweep method, which is a road dust measurement method suggested by the US-EPA [35]. The vacuum sweep method collects silt accumulated on the paved road surface by using a vacuum cleaner, measures the weight of the silt by using sieve analysis, and divides this by the sampled road area to calculate the silt loading. Silt loading (sL) refers to the weight of piled up silt with a geometric diameter \(\leq\)75 \(\upmu\)m per unit road area, which indicates the rescattering potential  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Test ID** & **Depth (mm)** & **Length (mm)** & **Condition** & **Cut Area (m\({}^{2}\))** \\ \hline
1 & 50 & 800 & Dry & 0.04 \\
2 & 70 & 800 & Dry & 0.056 \\
3 & 100 & 800 & Dry & 0.08 \\
4 & 100 & 800 & Wet & 0.08 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Experimental conditions.  
Figure 6: (**a**) Preparation of asphalt concrete specimen and (**b**) chamber experimental setup.  
of road dust. In this study, the vacuum sweep method was used to analyze the residual, rescattered PM after cutting the asphalt road pavement, and was calculated as follows. (1) After the cutting activity was finished, the PM present in the chamber and specimens was collected using an industrial vacuum cleaner. (2) The collected PM was sieved. The sL was calculated by dividing the weight of the silt that has passed through a 200-mesh sieve by the cutting area of the asphalt specimen. The deposited PM was analyzed using this method.  
SEM/EDS (Merlin Compact, Carl Zeiss, Jena, Germany) and XRD (Bruker-AXS, Shibuya, Tokyo, Japan) analyses were performed to analyze information, such as shape, particle size, and chemical composition of the PM generated from the asphalt concrete-cutting activity. Elemental components, such as C, O, Na, Mg, Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Cu, Fe, Ni, and Zn, were analyzed by EDS at specified SEM analysis conditions at an acceleration voltage of 15 kV and a working distance (WD) of 10 mm, while adjusting the magnification according to the sample to be analyzed. Furthermore, the analyzed sample was coated with Pt to increase the accuracy of the analysis. The content of the elements analyzed by EDS was expressed in weight %.