## 2 Materials and Methods
### Methods  
This study was carried out in seven stages. Firstly, in Stage 1, the modification of the conventional binder and the characterization of the modified binders were carried out. In this stage, the binders 3% NC (modified by 3% nanoclay in relation to the weight of CAP 50/70) and 3% NC + 2% SBS (modified by 3% of nanoclay and 2% of SBS polymer) were obtained. The content of nanoclay was established as 3% based on the results of a previous optimization study developed by [PERSON] [22], who evaluated the permanent deformation resistance of asphalt mixtures produced with binders modified by 1%, 2%, and 3% of nanoclay and verified a better performance for the 3% NC mixture. This nanoclay content was also identified in a recent study [39] as the most frequent value mentioned in the related literature. The addition of 2% SBS together with 3% NC was aimed at obtaining an asphalt material with elastic recovery. Low polymer content was adopted based on results reported by [PERSON] et al. [20], who studied the modification with 2.5% of nanoclay and 2.5% of SBS, and also for economic reasons. It means the authors would like to produce a binder with reduced polymer content due to the cost of this material. However, another optimization of the modifier amount, including the SBS content, is recommended for future studies. The inclusion of nanoclay and the polymer SBS in the base binder CAP 50/70 was carried out in a laboratory high shear mixer (Silverson, model L5M-A), and the modification procedures were defined based on studies reported in the literature [5; 11; 12; 15; 16; 17; 18; 19; 20]. The modification to produce the 3% NC \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Property** & **Unit** & **Standard** & **Result** \\ \hline Penetration & 0.1 mm & ASTM D 5 [35] & 50 \\ Softening point & \({}^{\circ}\)C & ASTM D 36 [36] & 73.0 \\ Elastic recovery & \% & ABNT NBR 15086 [38] & 90 \\ Apparent viscosity & & & \\ at 135 \({}^{\circ}\)C (_spindle_ 21, 20 rpm) & & & 1910 \\ at 150 \({}^{\circ}\)C (_spindle_ 21, 50 rpm) & & & 640 \\ at 175 \({}^{\circ}\)C (_spindle_ 21, 100 rpm) & & & 290 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Characterization of the asphalt binder modified by styrene–butadiene–styrene (SBS) polymer (SBS 60/85). \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Property** & **Unit** & **Standard** & **Result** \\ \hline Penetration & 0.1 mm & ASTM D 5 [35] & 57 \\ Softening point & \({}^{\circ}\)C & ASTM D 36 [36] & 47.9 \\ Thermal susceptibility index & - & - & -1.44 \\ Brookfield viscosity & & & \\ at 135 \({}^{\circ}\)C (_spindle_ 21, 20 rpm) & & & 290 \\ at 150 \({}^{\circ}\)C (_spindle_ 21, 50 rpm) & & & 150 \\ at 175 \({}^{\circ}\)C (_spindle_ 21, 100 rpm) & & & 60 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Characterization of the conventional asphalt binder (CAP 50/70). binder was carried out at 150 \({}^{\circ}\)C, with a shearing speed of 5000 rpm and compatibilization period of 100 min. In this regard, the previously mentioned literature review study [39] also identified the following values as more frequent in similar studies: temperature of 160 \({}^{\circ}\)C, mixing speed of 4000 rpm, and mixing process duration of 120 min. This indicates this work is consistent with the literature, since the adopted and mentioned values are close. In the case of the 3% NA + 2% SBS binder, a modification temperature of 180 \({}^{\circ}\)C and a mixing period of 180 min were adopted, maintaining the shearing speed of 5000 rpm. These differences in time and temperature of modification were established in order to allow the complete dispersion of the modifiers. However, it should be noted that this can also do some influence on the binders and mixtures behavior.