## 3 Test Methods and Result for Analysis of Swelling Property of Water-Expandable Polyurethane
### Swelling and Leakage Test Methods and Results
#### 3.2.1 Swelling Rate Test Method and Results under Deterioration Conditions
\begin{table}
\begin{tabular}{c c c c} \hline
**Pretreatment Item** & **Temperature and Heated Welding Speed** & **Standard** \\ \hline Free-thaw & 1 Cycle & Freezing in air and thawing in water, 50 cycles & KS F 2604 \\  & 1 Cycle & Freezing at \(-20\pm 2\)\({}^{\circ}\)C for 80 min, thawing & KS F 2604 \\  & & (spraying) at \(10\)\({}^{\circ}\)C-\(30\)\({}^{\circ}\)C for 20 min & \\ \hline  & & Repeated wet-dry, 50 cycle & Detailed Evaluation and \\  & & Maintained for 1 h at 20 \({}^{\circ}\)C and 98\% humidity; & Technical Review Operation \\  & & 1 h required to raise the temperature and & Standards for the Selection of \\  & & humidity from 20 \({}^{\circ}\)C and 98\% to 60 \({}^{\circ}\)C and 50\% & Waterproofing Method inside \\  & & Maintained for 1 h at 60 \({}^{\circ}\)C and 50\% humidity; & waterworks Facilities in the \\ Repeated & & 1 h required to lower the temperature and & Seoul Waterworks Authority \\ wet-dry cycle & 1 Cycle & humidity from 60 \({}^{\circ}\)C and 50\% to 20 \({}^{\circ}\)C and 98\% & \\  & & Maintained for 1 h at 20 \({}^{\circ}\)C and 98\% humidity; & \\  & & 1 h required to lower the temperature from 20 \({}^{\circ}\)C & at 98\% humidity to \(-10\)\({}^{\circ}\)C & \\  & & Maintained for 1 h at a temperature of \(-10\)\({}^{\circ}\)C; & 1 h required to raise the temperature from \\  & & \(-10\)\({}^{\circ}\)C to 20 \({}^{\circ}\)C at 98\% humidity & \\ \hline \end{tabular}
\end{table} 
Table 6: _Cont._  
Figure 12: The deterioration status of specimens: (**a**) Hydrochloric acid treatment; (**b**) Nitric acid treatment; (**c**) Sulfuric acid treatment; (**d**) Alkali treatment; (**e**) Sodium chloride treatment; (**f**) Freeze-thaw treatment; (**g**) Repeated wet-dry treatment. The evaluation results confirmed that the swelling rate increased as the superabsorbent polymer content increased in all the specimens; however, the degree of expansion varied depending on the superabsorbent polymer mixing ratio. In the case of the untreated specimen, the swelling rate increased from 15% at a mixing ratio of 1% to 298% at a mixing ratio of 20%. Moreover, the swelling rate was 12% to 213% for the hydrochloric acid treatment, 12% to 221% for the nitric acid treatment, 13% to 215% for the sulfuric acid treatment, 14% to 236% for the alkali treatment, 13% to 235% for the sodium chloride treatment, 14% to 251% for the freeze-thaw treatment, and 14% to 250% for the repeated wet-dry treatment. The above results suggest that when the superabsorbent polymer is exposed to deterioration conditions, the absorption recovery ratio decreases to a certain extent, and the swelling rate does not recover to 100%. In addition, when analyzed based on the minimum swelling rate of 150% for water-expandable polyurethane to exert its waterproofing performance, the test specimens subjected to deterioration may not exert  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{\ \begin{tabular}{c} **Sample** \\ **Number** \\ **Number** \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} **Mixing** \\ **Ratio** \\ **(\%)** \\ \end{tabular}  } & \multicolumn{6}{c}{**Swelling Rate according to Deterioration Conditions (\%)**} & \\ \cline{3-10}  & & & **Hydrochloric** & **Aclid** & **Silfluoric Acid** & **Akali** & **Solium** & **Freeze-** & **Repeated Wet-Dry** \\  & & & **Acid** & **Aid** & **Akali** & **Chloride** & **Thaw** & **Treatment** \\ \hline \#1 & 1 & 15 & 12 & 12 & 13 & 14 & 13 & 14 & 14 \\ \hline \#2 & 2 & 23 & 18 & 19 & 18 & 20 &  
the waterproofing performance at a superabsorbent polymer mixing ratio of less than 13% under hydrochloric acid, nitric acid, and sulfuric acid treatment conditions. However, it can be confirmed that all the specimens subjected to deterioration can exert waterproofing performance at a superabsorbent polymer mixing ratio of 14% or higher. In addition, it was found that the degree of decrease in the swelling rate according to each deterioration treatment varies.