# Methodology for Efficient Bitumen Storage with Reduced Energy Consumption
## 3 Results and Discussion  
### Physical Properties Evaluation  
The penetration and softening point tests results, after each thermal treatment and at every ageing stage, are presented in Table 2. The residual penetration and the increment of softening point were calculated after the RTFOT using Equations (7) and (8), respectively [18]:  
\[\text{Residual Penetration (\%)}=\text{P}_{\text{after}}/\text{P}_{\text{before}}, \tag{7}\]  
\[\text{Increment of Softening point ($\lx@math@degree${}^{\circ}$C)}=\text{SP}_{\text{after}}- \text{SP}_{\text{before}}. \tag{8}\]  
The penetration value of 35/50 paving grade bitumen should be between 35 and 50 [0.1 mm], and its softening point between 50 and 58 \(\lx@math@degree\)C. After short-term ageing, residual  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Functional Group**} & \multirow{2}{*}{**Bond Vibration**} & **Absorption Wavenumber** \\  & & **(cm\({}^{-1}\))** \\ \hline Carbonyls & C=O stretching & 1740–1690 \\ \hline Aromatic structures & C=C stretching & 1620–1560 \\ \hline Aliphatic structures (Methyl) & CH\({}_{3}\) asymmetric bending & 1460 \\ \hline Branched aliphatic structures & \multirow{2}{*}{CH\({}_{3}\) symmetric bending} & \multirow{2}{*}{1375} \\ (Methylene) & & \\ \hline Sulfoxides & S=O stretching & 1055–1030 \\ \hline Aromatic structures & C–H 1,3-disubstituted & \multirow{2}{*}{864} \\  & bending & \\ \hline Aromatic structures & C–H 1,4-disubstituted & \multirow{2}{*}{814} \\  & bending & \\ \hline Aromatic structures & C–H monosubstituted & \multirow{2}{*}{743} \\  & bending & \\ \hline Aromatic structures & C–H monosubstituted & \multirow{2}{*}{724} \\  & bending & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Absorption wavenumbers of functional groups in bitumen.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multirow{2}{*}{\begin{tabular}{c} **Ageing** \\ **Stage** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Penetration at** \\ **25 \lx@math@degree${}^{\circ}$C (0.1 mm) \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Softening** \\ **Point R\&B** \\ **(\lx@math@degree${}^{\circ}$C)** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Residual** \\ **Penetration** \\ **(\%)** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Incement of** \\ **Softening** \\ **Point (\lx@math@degree${}^{\circ}$C)** \\ \end{tabular} } \\ \hline BP & & 42 & 53.0 & - & - \\ BP + TC & Unaged & 43 & 52.2 & - & - \\ BP + RT & & 41 & 53.2 & - & - \\ \hline BP & RTFOT- & 26 & 58.0 & 61.90 & 5.0 \\ BP + RT & aged & 26 & 59.0 & 60.46 & 6.8 \\ \hline BP & & 27 & 59.0 & 65.85 & 5.8 \\ BP + TC & RTFOT + & 18 & 65.6 & - & - \\ BP + RT & PAV-aged & 17 & 64.8 & - & - \\ BP + RT & & 17 & 66.8 & - & - \\ \hline \hline \end{tabular}
\end{table}
Table 2: Penetration and softening point tests results.  
penetration should be \(\geq\) 53%, and the increment of softening point should be \(\leq\) 8 \({}^{\circ}\)C. We can observe from the results in Table 2 and the histograms in Figure 4; Figure 5 that our bitumen kept its conformity to 35/50 bitumen standards after being stored at room temperature (25 \({}^{\circ}\)C) and thermally cycled between 140 and 160 \({}^{\circ}\)C, at both post-storage and short-term ageing stages. We can consider the difference negligible, which means that both thermal storage methods did not affect the binder's physical properties. After the long-term ageing stage, penetration results were the same, the softening point showed a higher increase after room temperature storage, but it is still a slight difference of 1.2 \({}^{\circ}\)C. From the increment of softening point values and residual penetration values, it is clear that BP + TC has aged the most after short-term ageing.