# Evaluation of Short-Term Aging Protocol for Asphalt Mixtures
## 3 Results and Discussion
### Binder Test Results
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline
**Bitumen Source** & \multicolumn{8}{c}{**BAPCO-Bahrain**} \\ \hline
**Bitumen Grade** & \multicolumn{8}{c}{**PG 76-10**} \\ \hline
**Binder Type/Recovered from** & **Original Binder** & **RTFOO-Conditioned** & \multicolumn{4}{c}{**Mix 3**} \\ \cline{3-10}  & **(OB)** & **Binder** & **From Field** & **From Lab-S135T4** \\ \hline Brookfield \(\eta\)@135 \({}^{\circ}\)C, cP & 1778 & 2175 & 2234 & 2145 \\ \hline Brookfield \(\eta\)@165 \({}^{\circ}\)C, cP & 464 & 457 & 455 & 448 \\ \hline True-Grade High Temperature, \({}^{\circ}\)C & - & 80.5 & 82.1 & 80.7 \\ \hline True-Grade Intermediate & \multicolumn{8}{c}{-} & 18.5 & 18.9 & 17.6 \\ \hline MSCR \(J_{nr}\) (3.2 kPa)@76 \({}^{\circ}\)C & - & 2.48 & 2.15 & 2.46 \\ \hline MSCR \(\%\)\(J_{nr}\) difference @76 \({}^{\circ}\)C & - & 47.8 & 53.3 & 48.05 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Summary of binder test results for modified mixture (mixture 3). \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Bitumen Source** & \multicolumn{8}{c}{**BAPCO-Bahrain**} \\ \hline
**Bitumen Grade** & \multicolumn{8}{c}{**PG 60/70**} \\ \hline
**Binder Type/Recovered from** & **Original Binder** & **RTFOO-Conditioned** & \multicolumn{4}{c}{**Mix 3**} \\ \cline{3-10}  & **(OB)** & **Binder** & **From Field** & **From Lab-S135T4** \\ \hline Brookfield \(\eta\)@135 \({}^{\circ}\)C, cP & 1778 & 2175 & 2234 & 2145 \\ \hline Brookfield \(\eta\)@165 \({}^{\circ}\)C, cP & 464 & 457 & 455 & 448 \\ \hline True-Grade High Temperature, \({}^{\circ}\)C & - & 80.5 & 82.1 & 80.7 \\ \hline True-Grade Intermediate & \multicolumn{8}{c}{-} & 18.5 & 18.9 & 17.6 \\ \hline MSCR \(J_{nr}\) (3.2 kPa)@76 \({}^{\circ}\)C & - & 2.48 & 2.15 & 2.46 \\ \hline MSCR \(\%\)\(J_{nr}\) difference @76 \({}^{\circ}\)C & - & 47.8 & 53.3 & 48.05 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Summary of Binder test results for unmodified mixture (mixture 3). Brookfield viscosity results of binders recovered from mixtures 1 and 2 showed that the viscosity increased with the increase of the duration of short-term aging as presented in Table 6 and Figures 10 and 11. The results also demonstrated that conditioning asphalt mixtures (mixtures 1 and 2) for 4 h at 135 \({}^{\circ}\)C was the closest condition to the viscosity results of asphalt binders extracted from loose mixtures (Figures 10 and 11). Furthermore, the true PG and MSCR test results showed that the conditioning mixtures at the same conditions at 135 \({}^{\circ}\)C for 4 h were close to those of loose mixtures, especially for mixture 2, while it was slightly off for mixture 1. A very similar result was obtained for mixture 3, that is, 4 h of conditioning the lab mixture closely simulated the RTFO-aged binder and the mixture from the field (Figure 12). Therefore, considering the results of the mechanical properties (dynamic modulus) and binder tests, conditioning asphalt mixtures at 135 \({}^{\circ}\)C for 4 h can adequately simulate the short-term aging of most asphalt mixtures used in the State of Qatar. Figure 11: Comparison of viscosity results of unmodified binders recovered from mixture 2. Figure 12: Comparison of viscosity results of modified binders recovered from mixture 3.