## 4 Conclusions  
According to the objective previously defined, this study enabled four different asphalt mixtures to be compared in terms of their rheological behavior, resistance to permanent deformation, and resistance to fatigue cracking. The mixtures were prepared with different binders as follows: conventional (CAP 50/70), modified with nanoclay (3% NC), modified with SBS polymer (SBS 60/85), and modified with both nanoclay and SBS (3% NC + 2% SBS).  
Based on the results obtained in this study, the mixture modified with the binder 3% NC + 2% SBS showed a better rheological behavior and a higher resistance to permanent deformation. This mixture presented the highest values for the complex modulus and the lowest phase angles, which is considered an indication of higher resistance to rutting. In the permanent deformation tests, it showed the lowest percentage of rutting depth, thus confirming the predictions based on the rheological study.  
On the other hand, considering the fatigue tests results, a better resistance was observed in the SBS 60/85 mixture. In this respect, the predictions made according to the rheological behavior were partially verified. Even so, on the next stage of this study, numerical simulations of pavement structures demonstrated the use of the 3% NC + 2% SBS surface as a replacement for the SBS 60/85 being technically viable (with thickness adjustments), and considering the possibility of reducing costs from this substitution, it could also be economically viable. In this sense, considering the costs of the materials used in the research, it is believed that the mixture modified by nanoargila and SBS (with lower content) would be cheaper than that modified by a higher SBS content. However, economic viability with specific comparisons should be verified in future studies.  
Thus, it is concluded that the use of polymers science together with the application of nanotechnology can lead to great advances in the area of modified asphalt mixtures for use on roadways where a higher performance of the paving materials is required. Especially in relation to rutting, it is highlighted that this alternative has great potential to provide improved asphalt surfaces, mainly in regions of tropical climate and on highways submitted to slow heavy traffic.  
Conceptualization, G.C.C., G.T., J.V.S.d.M. and M.F.M.; methodology, G.C.C., G.T., J.V.S.d.M. and M.F.M.; formal analysis, G.C.C., G.T., J.V.S.d.M., M.F.M., L.P.T. and L.C.d.L.; investigation, G.C.C., G.T., J.V.S.d.M. and M.F.M.; writing--original draft preparation, G.C.C. and T.G.; writing--review and editing, G.C.C., G.T., J.V.S.d.M., M.F.M., L.P.T. and L.C.d.L.  
This research was funded by NATIONAL COUNCIL FOR SCIENTIFIC AND TECHNOLOGICAL DEVELOPMENT (CNPq), grant number 130697/2015-0, and by ASPHALT TECHNOLOGY NETWORK/PETROBRAS, grant number 2014/00282-9.  
The authors would like to thank the National Council for Scientific and Technological Development (CNPq), and the Asphalt Technology Network/Petrobras. We are also grateful to Greca Asfaltos S.A. (for supplying the binders CAP 50/70 and SBS 60/85) and to Kraton (for providing the SBS polymer).  
The authors declare no conflict of interest.