# Characterization of Asphalt Binders Modified with Bio-Binder from Swine Manure
## 4 Conclusions  
In this study, a bio-binder obtained from swine manure was evaluated as a binder modifier at different rates (0%, 10%, and 20%) to two commercial asphalt binders (15/25 and 50/70) through several characterization tests. The results showed a softening effect of  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline  & **As** & **Ba** & **Cd** & **Cr** & **Cu** & **Hg** & **Mo** & **Ni** & **Pb** & **Sb** & **Se** & **Zn** \\ \hline Results & \textless{}0.01 & 0.63 & \textless{}0.002 & 0.03 & \textless{}0.02 & \textless{}0.0005 & 0.03 & \textless{}0.03 & \textless{}0.02 & \textless{}0.02 & \textless{}0.02 & \textless{}0.01 \\ \hline \({}^{1}\) Inert waste (mg\(\cdot\)kg\({}^{-1}\)) & 0.50 & 20.0 & 0.04 & 0.50 & 2.00 & 0.01 & 0.50 & 0.40 & 0.50 & 0.06 & 0.10 & 4.00 \\ \hline \hline \end{tabular} \({}^{1}\) Limit for acceptance at landfills.  
\end{table}
Table 4: Leaching concentrations (mg\(\cdot\)kg\({}^{-1}\)) after leaching test (EN 12457-4) and limits for acceptance at landfills for inert waste.  
Figure 10: Leaching of a bio-binder sample in the presence of water: (**a**) week 0, (**b**) week 1, (**c**) week 2, (**d**) week 3, and (**e**) week 4.  
the bio-binder. As the bio-binder content increased, the penetration increased, while the softening temperature, the Fraass breaking point, and the viscosity decreased. A decrease in the flash point was also observed as the bio-binder content increased, as the bio-modified asphalt binder has also been observed, showing the importance of temperatures during the asphalt mixtures manufacturing process.  
The results of the UCL method showed that bio-modified asphalt binder has a worse thermal susceptibility (it is more brittle at low temperatures and more inconsistent at high temperatures) and poorer resistance to ageing compared to the reference bitumen. This was caused, in part, to the temperature to which the bio-binder was subjected during the manufacture of the mixture. On the other hand, the resistance to moisture damage is better.  
Finally, despite de fact that leaching phenomena were observed in the presence of water, the asphalt mixture with bio-modified binder can be classified as non-hazardous waste, presenting no environmental problems.  
Conceptualization, J.G. and L.V.; methodology, J.G., L.V., R.M. and A.H.M.; formal analysis, J.G., T.L.-M., L.V., R.M. and A.H.M.; investigation, J.G., T.L.-M., L.V., R.M., C.B. and A.H.M.; resources, J.G. and R.M.; data curation, [PERSON], L.V. and R.M; writing--original draft preparation, [PERSON]-M., R.M. and A.H.M.; writing--review and editing, [PERSON], T.L.-M., L.V., R.M., C.B. and A.H.M.; visualization, T.L.-M., R.M. and A.H.M.; funding acquisition, [PERSON] All authors have read and agreed to the published version of the manuscript.  
This research was partially funded by the Centre for Industrial Development and Technology (CDTI) of the Spanish Ministry of Science and Innovation, grant number IDI-20200468.  
Not applicable.  
The data presented in this study are available on request from the corresponding author.  
The authors would like to thank the Ciesm-Intevia road laboratory for the contribution in the realization of the tests. [PERSON] is a Serra Hunter Fellow.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.