# Effect of PVA/PVAc Based Polymer Coating on Dust Reduction in Playground
## 2 Experimental Section
### Experimental Methods  
The soil samples were examined for specific gravity, moisture content, permeability test, liquid limit, and plastic limit following ASTM D792 [31], ASTM D2216-19 [32], ASTM D2434-19 [33], and ASTM D4318 [34], respectively. The in situ density test was conducted in accordance with the sand-cone method (ASTM D1556 [35]) to evaluate the compact ability of the surface layer. The in-situ density test was conducted at K elementary school in Seoul. Figure 2 shows the site construction (area about 2800 m\({}^{2}\)) using coated soil samples. Figure 3 depicts the schematic presentation of the permeability test conducted on soil samples. First, a sub-base layer of 150 mm height was laid which contained mixed aggregates of sizes ranging from 5 mm to 25 mm. Secondly, a base layer of 50 mm containing sandy loam particles was laid. Finally, a layer of 100 mm height containing coated soil particles was laid. The simulated drainage performance test of the specimen was conducted by measuring the time and amount of water drained. After arranging the layers, 18 L of water was poured on the top surface layer and the duration of 1 L of water drainage was recorded. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Oxides (\%)** & **Pumice** & **Loam** & **Oxides (\%)** & **Pumice** & **Loam** \\ \hline SiO\({}_{2}\) & 48.6 & 59 & Na\({}_{2}\)O & 2.66 & 1.57 \\ Fe\({}_{2}\)O\({}_{3}\) & 14.99 & 8.035 & TiO\({}_{2}\) & 2.69 & 1.09 \\ Al\({}_{2}\)O\({}_{3}\) & 16.11 & 21.15 & P\({}_{2}\)O\({}_{5}\) & 0.394 & 0.317 \\ CaO & 8.687 & 2.55 & MnO & 0.18 & 0.13 \\ MgO & 2.66 & 1.87 & SrO & 0.166 & 0.0563 \\ K\({}_{2}\)O & 2.44 & 3.94 & SO\({}_{3}\) & 0.118 & 0.111 \\ Cl & 0.0963 & 0.069 & - & - & - \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Chemical composition of the raw materials by the XRF method. \begin{table}
\begin{tabular}{c c} \hline \hline
**Appearance** & **Clear and Pale Yellow** \\ \hline Melting Point & 150–230 \({}^{\circ}\)C \\ Density & 1.2–1.3 g/cm\({}^{3}\) \\ Specific Heat & \(1.9\times 10^{3}\) J/kg \({}^{\circ}\)C [0.45 kcal/kg \({}^{\circ}\)C] \\ Combustion Heat & \(1.1\times 10^{5}\) J/mol [5700 kcal/kg] \\ Solubility Water & Soluble \\ Flash Point & Assumed to be the same as PVA \textgreater{} 70 \({}^{\circ}\)C (Seta method) \\ Auto-ignition Temperature & Assumed to be the same as PVA \textgreater{} 370 \({}^{\circ}\)C \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Physical and chemical properties of PVA film. TSI 8533 Dust Track (Dust Track Drx Aerosol monitor 8533, TSI, Minnessota, USA) was used to measure dust production. Normally, there are two main causes of dust generation in playgrounds: the first by wind flow and the second by human activity. Therefore, the dust generation due to both factors was investigated in this study. Figure 4 displays the experimental setup for measuring the dust generation caused by wind flow. The wind effect measurement setup comprised of a platform made with acrylic sheets of dimensions of 1000 \(\times\) 600 \(\times\) 1000 mm\({}^{3}\). The experiment was carried out on four different kinds of soil samples coated with 0%, 7%, 10%, and 12% of coating solution. The dust tracker device was placed in the center of the experimental setup. Dust measurement was carried out at intervals of 10 s for a total duration of 1 h. In addition, the dust tracker was calibrated prior to every use by following the standard calibration manual of the instrument. A fan was used to produce the constant wind flow. The fan was placed 500 mm away from the setup. Figure 5 shows the details of the test setup to measure the dust generation due to human activity. The experimental setup consisted of wooden frames and laminated wooden sheets with dimensions of 1500 \(\times\) 600 \(\times\) 3000 mm\({}^{3}\). A simulated playground composed of three layers was used in this experiment. The details of each layer are shown in Figure 5. The dust monitoring device was placed at the center of the experimental setup as shown in Figure 5a.