## 4 Discussion  
### Binary Systems \"Bitumen-Additive\"  
As evidenced by the experimental data presented in Table 6, in the absence of additives, the bitumen surface (\(\theta\) = 95.05\({}^{\circ}\)) was in the border region between hydrophilicity and hydrophobicity. The addition of a limited concentration (C \(\leq\) 1 g/dm\({}^{3}\)) of a sealing liquid into bitumen led to an increase in the contact angle of wetting \(\theta\). Thus, at C = 1 g/dm\({}^{3}\) of the modifier of polymeric nature, the value of \(\theta\) increased by 12.25\({}^{\circ}\) relative to the base case and amounted to 107.30\({}^{\circ}\). However, with a higher concentration of AG-4I, the opposite effect was recorded, a decrease in the contact angle of wetting up to 96.15\({}^{\circ}\) at C = 2 g/dm\({}^{3}\). Figure 5: Partial dependencies of the contact angle (**a**) and the water saturation index (**b**) on the content of AC-1 and AG-4I: 1—AC-1; 2—AG-4I. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**C\({}_{\text{AC-1}}\), g/dm\({}^{3}\)**} & \multirow{2}{*}{\(\theta\), \({}^{\circ}\)} & \multirow{2}{*}{\(\mathbf{W}\), \%} & \multirow{2}{*}{\(\mathbf{C}_{\text{AG-4I}}\), g/dm\({}^{3}\)} & \multirow{2}{*}{\(\theta\), \({}^{\circ}\)} & \multirow{2}{*}{\(\mathbf{W}\), \%} \\ \cline{5-10}  & & & & & & & & & \\ \hline
0 & 103.87 & 5.51 & 0.0 & 101.21 & 5.74 \\
0.5 & 106.03 & 4.82 & 0.5 & 104.80 & 4.70 \\
1.0 & 109.75 & 4.14 & 1.0 & 112.17 & 3.52 \\
1.5 & 109.40 & 4.05 & 1.5 & 110.43 & 4.20 \\
2.0 & 109.01 & 4.21 & 2.0 & 109.45 & 4.57 \\ \hline \hline \end{tabular}
\end{table} 
Table 11: Sample of response functions for each level of concentration factors of two additives. It should be noted that the concentration (C = 1 g/dm\({}^{3}\)), which ensured the maximum hydrophobic effect, was also preserved in the presence of two other modifiers (AMDOR-10 and AC-1). With the same quantitative content of additives of amphiphilic nature, the \(\theta\) values increased by 8.16\({}^{\circ}\) (AC-1) and 6.76\({}^{\circ}\) (AMDOR-10) relative to unmodified bitumen and amounted to 103.21\({}^{\circ}\) and 101.81\({}^{\circ}\), respectively. Thus, their hydrophobic effect turned out to be 1.5-1.8 times lower than that of AG-4I. Another distinguishing feature is the stabilization of the values of the contact angle of wetting outside the indicated concentration range (C > 1 g/dm\({}^{3}\)). The observed changes in the contact angle of wetting with water of the modified bitumen coatings were consistent with the isotherms of surface tension (\(\sigma_{\text{1-g}}\)) and at the same time found their explanation from the standpoint of the formation of a surfactant adsorption layer on the \"bitumen-air\" interface. Judging by the isotherms of the surface tension of binary systems \"bitumen-additive\" in the concentration range of additives C \(\leq\) 1 g/dm\({}^{3}\), the presence of diphilic molecules in the bulk phase of bitumen stimulated their concentration in the surface layer, which was confirmed by a decrease in the values of surface tension (Table 6). In accordance with the Rebinder polarity equalization rule [52] on the interfacial surface, the surfactant molecules were oriented by the polar group into bitumen, and the hydrocarbon radicals turned out to be facing the air. This structure of the adsorption layer created a hydrophobic effect, which in turn was controlled by the length, branching of the hydrocarbon radical, and the number of hydrocarbon chains [53]. This clearly demonstrated the comparison of \(\sigma_{\text{1-g}}\) and \(\cos\theta\) in isoconcentration (C = 1 g/dm\({}^{3}\)) binary systems, \"bitumen-AG-4I\" and \"bitumen-AC-1\".