## 3 Results and Discussion
### Water Stability of the Aggregates  
The cumulative number of disintegrated aggregates was recorded every minute for 10 min and the stability percent values, noted as \(K\), are shown in Table 3. A significant increase in the water stability of the aggregates was observed due to the ADNB treatment. For example, in the test group of 7.5 mm aggregates, \(K\) increased to over 90% when treated with 3% ADNB, which was approximately 17 times higher than that of the untreated aggregates. Similarly, \(K\) increased to 98.5% when treated with 5% ADNB, which was approximately 19 times higher than that of the untreated aggregates. Furthermore, less soil was washed off and/or fewer aggregate structures were destroyed by water due to the significant increase in the water stability of the aggregates. As a result, the erosion resistance of slope topsoil was improved.  
It was also observed that even when treated with the same concentration of polymer solution, the \(K\) values of the 15 mm aggregates were higher than those of the 7.5 mm aggregates. For example, when treated with 2% ADNB, the \(K\) value of of the 15 mm aggregate was 97%, which was 1.5 times that of the 7.5 mm aggregate. Additionally, when treated with 3.0% ADNB and 5.0% ADNB, the \(K\) values of the samples increased to 100%, which indicated that the aggregates maintained their integrity during the immersion period of 10 min. This result could be explained by the fact that the aggregates with larger diameters had smaller specific surface areas, on which there were larger amounts of effective polymer emulsions than on the aggregates with smaller diameters.  
Figure 7 shows the comparison of the \(K\) values of the aggregates with average diameters of 7.5 mm and 15 mm. Almost no difference in the \(K\) value was observed when the aggregates were treated with a high-concentration polymer solution (higher than 2% ADNB). This result may have been due to the amount of polymer that exceeded the amount required for bonding in the samples. Based on the analysis results obtained from the effective infiltration test, the polymer solution with a concentration of 3%/5% ADNB could rapidly fill the pores of the surface soil layer due to its high proportion of polymer material, which led to the halting of infiltration of the additional polymer emulsion and the formation of a thick film on the surface. The film could then prevent the aggregates from disintegration during the 10 min immersion (Figure 8).  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Test Group**} & \multicolumn{8}{c}{**Immersion Time (min)**} & \multirow{2}{*}{**Stability K (\%)**} \\ \cline{2-11}  & & **1** & **2** & **3** & **4** & **5** & **6** & **7** & **8** & **9** & **10** \\ \hline
7.5-UNT & 50 & 50 & 50 & 50 & 50 & 50 & 50 & 50 & 50 & 50 & 5 \\
15-UNT & 50 & 50 & 50 & 50 & 50 & 50 & 50 & 50 & 50 & 50 & 5 \\
7.5-ADNB 0.5\% & 8 & 35 & 50 & 50 & 50 & 50 & 50 & 50 & 50 & 16.4 \\
15-ADNB 0.5\% & 10 & 20 & 21 & 34 & 35 & 45 & 50 & 50 & 50 & 32 \\
7.5-ADNB 1.0\% & 0 & 5 & 13 & 20 & 30 & 38 & 40 & 45 & 48 & 50 & 47.2 \\
15-ADNB 1.0\% & 0 & 0 & 0 & 5 & 11 & 25 & 30 & 41 & 45 & 45 & 64.1 \\
7.5-ADNB 2.0\% & 5 & 5 & 8 & 13 & 16 & 21 & 27 & 30 & 32 & 35 & 65.1 \\
15-ADNB 2.0\% & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 5 & 5 & 10 & 97 \\
7.5-ADNB 3.0\% & 0 & 0 & 0 & 3 & 3 & 5 & 5 & 8 & 10 & 13 & 91.9 \\
15-ADNB 3.0\% & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 100 \\
7.5-ADNB 5.0\% & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 3 & 3 & 3 & 98.5 \\
15-ADNB 5.0\% & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 100 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Static water stability of the different aggregates.