## 4 Results and Discussion  
Due to the complex nature of bitumen and difficulties in distinguishing the discernible differences in the bitumens with similar physical properties, a comprehensive analysis requires detailed integration of chromatographic and spectroscopic data. In the context, it was shown that, for discriminating the differences of various bitumens, the understanding of structural and functional entities in asphaltene is playing a key role. It was found that asphaltene from different bitumens have different structural characteristics [22]. For this reason, in the present research, the \({}^{1}\)H-NMR analysis was conducted on both asphaltene and maltene fractions along with the bitumen samples. The \({}^{1}\)H-NMR spectra of the analyzed bitumens including neat samples, asphaltene, and maltene fractions are shown in Figures 4-6. All three spectra show a very similar distribution of signals: two strong absorption peaks at 0.85 and 1.25 ppm, which correspond to proton on methyl and methylene groups, respectively; and some other large bands at 2.3-3.8 ppm and at 5.8-8.5 ppm that correspond to alkyl proton on C\({}_{\alpha}\) and to aromatic protons, respectively. It should be noted that, in all spectra, no signal in the 4.5-6 ppm region is recorded, typically the olefinic region, which means that the amount of olefinic hydrocarbons, although present, is negligible. The four regions selected for each spectrum were integrated and normalized to get the fractional proton distributions directly from the integration curve. The fractional proton distributions of the three bitumen samples are given in Table 3.  
Comparing the values of hydrogen distribution reported in Table 3, it can be observed that the two paving bitumens have a similar distribution of hydrogen types, while the distribution corresponding to the industrial bitumen is very different from the first two. In detail, the area corresponding to the aromatic zone is nearly the same in the first two samples (8.00% and 8.32%), while it is markedly lower in the last one (4.82%). On the contrary, the industrial bitumen is characterized by a high percentage of aliphatic protons compared to the other bitumens (95.17% vs. \(\approx\)91.90%), most of them corresponding to aliphatic hydrogens in \(\alpha\) relative to aromatic rings, since, as can be seen in Table 3, the hydrogen percentage \(H_{\alpha}\), relating to the sample of industrial bitumen is much larger than the other two samples (16.10% vs. \(\approx\)3.8%). This means that the nature of the compounds of the first two samples is similar, \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Chemical Shift** & **Type of Protons** \\ \hline \(H_{\alpha}\) & 6.0–9.0 & Aromatic hydrogen \\ \(H_{\mathrm{ol}}\) & 4.0–6.0 & Olefinic hydrogen \\ \(H_{\alpha}\) & 2–0.40 & Aliphatic Hydrogen on \(C_{\alpha}\) to aromatic rings \\ \(H_{\beta}\) & 1.0–2.0 & Aliphatic Hydrogen on \(C_{\beta}\) and the CH\({}_{2}\) beyond the \(C_{\beta}\) to aromatic rings \\ \(H_{\gamma}\) & 0.5–1.0 & Aliphatic Hydrogen on \(C_{\gamma}\) and the CH\({}_{3}\) beyond the \(C_{\gamma}\) to aromatic rings \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Types of protons and chemical shift assignments [25]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Bitumen** & \multicolumn{4}{c}{**Hydrogen Distribution \(\pm\)0.05**} \\ \cline{2-5}  & \(H_{\alpha}\) & \(H_{\alpha}\) & \(H_{\beta}\) & \(H_{\gamma}\) \\ \hline Paving 70/100 & 8.00 & 3.86 & 64.38 & 23.73 \\ Paving 160/220 & 8.32 & 3.80 & 64.19 & 23.66 \\ Industrial 160/220 & 4.82 & 16.10 & 61.07 & 18.00 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Fractional proton distribution of the three bitumens obtained from the \({}^{1}\)H-NMR spectra reported in Figures 4, 5 and 6a. and rather different from the third sample. It should be here reminded that, while the second paving grade bitumen and the industrial bitumen have the same classification grade, they originated from two different processes, which affect their final chemical compositions.