# Effect of PVA/PVAc Based Polymer Coating on Dust Reduction in Playground
## 3 Results and Discussion
### Permeability Test Results  
Proper drainage of rainfall water is an essential parameter for playground soil. For this purpose, a permeability test was carried out on the soil samples. Figure 8a demonstrates the coefficient of permeability values for different soil samples. It is obvious that the soil sample coated with 0% coating solution showed the lowest permeability coefficient (4.05 \(\times\) 10\({}^{-4}\) cm/s). Whereas soil samples coated with 12% coating solution depicted the highest permeability coefficient value (5.99 \(\times\) 10\({}^{-4}\) cm/s). Apart from this, the coefficient of permeability increased with the increase in the amount of coating solution. For instance, soil samples coated with 7%, 10%, and 12% of coating solution depicted an increase of 18.5%, 28.6%, and 47.9% in the coefficient of permeability when compared to the soil samples coated with 0% coating solution. This increment in permeability is due to the coating effect, which reduced the porosity and cohesion among soil particles.  
Figure 8b depicts the relationship between the liquid limit, coefficient of permeability, and moisture content. There is linear relationship between the liquid limit and coefficient of permeability as well as between moisture content and coefficient of permeability. The physical behavior of soil is highly affected by water. For example, soil samples with a large absorption capacity requires more water to change from semi-solid to liquid state, and less water permeability. However, coating the particles reduced the absorption and ultimately reduced the water required to change the soil from semi-solid to liquid state and the permeability increased.  
The drainage performance of playground soil was evaluated using a simulated playground setup. Figure 9 shows the results of the simulated permeability test carried out on various soil samples. The X-axis of Figure 9 represents the total drainage, and the Y-axis indicates the time taken for drainage of that volume of water. Regardless of the presence of coating, no significant difference in drainage time was observed for up to 6 L of water. However, the drainage time began to vary beyond 7 L. In addition, the 8 L water drainage time of uncoated soil sample required 28 min more than the 12% coating solution contained samples, respectively. In the case of the uncoated sample, water was no longer draining after 8 L of water were discharged. However, an increase in the total drainage time was observed with increasing the amount of coating solution. For instance, the samples coated with 7%, 10%, and 12% showed total drainage of 9 L, 10 L, and 11 L at a similar time, respectively. The increase in water drainage may be attributed to the reduction in soil absorption and increase in permeability due to the effect of surface coating. These results  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Unit** & **Field Measurement No. 1 No. 2 No. 3** & **Field Measurement No. 3** \\ \hline Moisture content & \% & 10.8 & 10.3 & 10.6 \\ Maximum dry density & g/cm\({}^{3}\) & 1.922 & 1.922 & 1.922 \\ Field dry density & g/cm\({}^{3}\) & 1.745 & 1.753 & 1.750 \\ Compaction degree & \% & 90.8 & 91.2 & 91.05 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Field density measurement test results.  
Figure 12: Visual inspection (\(\times\)60) of (**a**) uncoated soil particle and (**b**) soil sample coated with 12% coating solution.  
Figure 13: PM\({}_{2.5}\) dust generation due to human activity in soil samples coated with 0% and 12% coating solution.