## 3 Results and Discussion  
### Asphalt Binder Test Results  
First, the differences between the binder materials were analyzed by using FTIR tests, and the corresponding results can be observed in Figure 1.  
The FTIR spectra show the chemical transformations/interactions that may or may not have occurred during asphalt binder production. The main absorbance peaks of the spectra of all asphalt binder materials occur in the same wavenumber ranges (700-1800 cm\({}^{-1}\) and 2800-3050 cm\({}^{-1}\)) because the results are mainly controlled by the conventional base bitumens. This means that the main functional groups of the conventional base bitumens (B35/50 and PG 64-22) are also present in the modified binders with waste motor oil and SBS (B35/50 & MotorOil & SBS) and with bio-oil and ground rubber (PG64-22 & cryoMBO). The spectrum of rubber modified bio-oil (cryoMBO) is slightly different from those of asphalt binder materials, mainly due to the presence of some moisture in the bio-oil [6]. Nevertheless, it was concluded that the new modified binders can be a good alternative to conventional bitumens, because they are chemically similar and/or compatible. The rheology of the asphalt binder materials was then evaluated with a dynamic shear rheometer (DSR), by carrying out frequency sweep tests at different temperatures. The stiffness master curves obtained with those tests are presented in Figure 2.  
The master curve of the modified binder with motor oil and SBS (B35/50 & MotorOil & SBS) shows a lower slope than that of conventional bitumen (B35/50), which may be associated with a low susceptibility of this binder to frequency and temperature changes. On the other hand, the rheological behavior obtained in the previous study with bio-binder (CryoMBO) [6] showed that it is comparable to conventional bitumen (PG64-22) and the modified binder (PG64-22 & cryoMBO), because all these materials present master curves with very similar shapes. The different behavior of the new binder developed in this study (B35/50 & MotorOil & SBS) may be related to the higher amount of elastomer (SBS) used, in comparison with the ground rubber amount (3%) used in the bio-oil study. The rheological results were also used to calculate the high temperature continuous performance grades of all asphalt binders, which are presented in Table 1. The addition of 10% waste motor oil and 5% SBS clearly increased the performance grade of the base bitumen B35/50, mainly due to the high amount of elastomer used. In turn, in the past study with bio-oil [6], 20% bio-binder (cryoMBO) was added to the base bitumen (PG 64-22), almost without changing its high temperature  
Figure 1: Fourier transform infrared (FTIR) spectra results of: (**a**) styrene-butadiene-styrene (SBS) elastomer, conventional bitumen (B35/50) and modified asphalt binder B35/50 & MotorOil & SBS; (**b**) Rubber modified bio-oil (cryoMBO), bitumen PG64-22 and modified asphalt binder PG64-22 & cryoMBO (adapted from [PERSON] et al. [6], @ AAPT, 2014). performance grade. Thus, the rheological results indicate that the new binder developed in this work (B35/50 & MotorOil & SBS) is rheologically or mechanically superior to the conventional bitumens and the modified binder PG64-22 & cryoMBO, particularly at high service temperatures, indicating its suitability for asphalt road pavements applied in hot climate zones. \begin{table}
\begin{tabular}{c c} \hline \hline
**Materials** & **High Temperature Continuous Performance Grade (\({}^{\circ}\)C)** \\ \hline Conventional bitumen (B35/50) & 65.1 \\ Modified asphalt binder (B35/50 \& MotorOil \& SBS) & 76.8 \\ Conventional bitumen (PG 64-22) & 66.6 \\ Rubber modified bio-oil (CryoMBO) & 61.3 \\ Modified asphalt binder (PG64-22 \& cryoMBO) & 65.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: High temperature continuous performance grade of conventional bitumens (B35/50 and PG 64-22), rubber modified bio-oil (CryoMBO) and modified asphalt binders (B35/50 & MotorOil \& SBS and PG64-22 \& cryoMBO).