# Phase Separation Study on the Storage of Technically Specification Natural Rubber Modified Bitumen
## 3 Results and Discussion
### Density and Viscosity of TSNR-Modified Asphalt  
Previously, in subchapter 3.3, it was explained that the storage stability of TSNR-modified asphalt is influenced by differences in density and viscosity between asphalt and TSNR components and TSNR-modified asphalt mixture. Table 3 shows the density and viscosity at the top and bottom of the TSNR-modified asphalt before and after the storage stability test. As seen in Table 3, the density of the TSNR-modified asphalt mixture at the top decreased and, on the other hand, increased over time, accompanied by an increase in viscosity. This also confirms the effect of density and viscosity on the phase separation in the TSNR-modified asphalt mixture. Changes in viscosity and density are affected by temperature and continuity of homogenization during storage. Spot coagulants will form if homogenization and temperature conditioning are not conditioned during storage. The density difference between components, as well as the viscosity of the mixture, are important factors in determining phase stability. Density changes are not spontaneous because the TSNR components take time to coalesce and flocculate before gravity-induced phase separation occurs. Within 48 h, the difference in density between the top and bottom becomes visible. The 8% TSNR-modified asphalt experienced a significant change in density within 48 h. Similarly, modified asphalt with 10 and 12% TSNR experienced smaller density changes during the same time period. Based on these findings, the amount of TSNR added to the asphalt influences whether phase separation occurs quickly or slowly. This relates to coalescence and flocculation in TSNR-modified asphalt, which is the first stage of destabilizing the TSNR and asphalt components [41; 42; 43]. Coalescence and flocculation also have an effect on how the mixture viscosity changes over time. Phase compatibility between components eventually collapses due to large density and viscosity differences. Gravity also encourages the formation of two-phase flows that move vertically to form the TSNR-rich phase side and the asphalt-rich phase side [6; 53]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multicolumn{2}{c}{**Density (kg/m3)**} & \multicolumn{2}{c}{**Viscosity (Pa.s)**} \\ \cline{2-5}  & **Top** & **Bottom** & **Top** & **Bottom** \\ \hline Aspal Pen 60/70 & 1034.670 & 1034.670 & 0.151 & 0.151 \\ TSNR & 868.560 & 868.560 & 0.517 & 0.517 \\
8\% TSNR-Modified Asphalt & & & & \\
0 h & 1023.560 & 1023.560 & 0.168 & 0.168 \\
24 h & 992.733 & 1020.640 & 0.426 & 0.593 \\
48 h & 987.080 & 1045.242 & 0.306 & 0.582 \\
10\% TSNR-Modified Asphalt & & & & \\
0 h & 1018.340 & 1018.340 & 0.211 & 0.211 \\
24 h & 1004.905 & 1019.777 & 0.245 & 0.251 \\
48 h & 977.199 & 1028.278 & 0.213 & 0.323 \\
12\% TSNR-Modified Asphalt & & & & \\
0 h & 1013.690 & 1013.690 & 0.270 & 0.270 \\
24 h & 1002.497 & 1021.247 & 0.483 & 0.706 \\
48 h & 993.526 & 1029.667 & 0.375 & 0.757 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Density and viscosity of TSNR-modified asphalt. The addition of TSNR to the modified asphalt initially increased its viscosity in order to improve mix compatibility. However, the coalescence and flocculation phenomena that occur with storage time influence the viscosity changes at the top and bottom. Furthermore, the viscosity of the top increased significantly as the density decreased, indicating the accumulation of the TSNR phase with lighter density at the top due to phase separation [41; 42; 61]. The viscosity of TSNR-modified bitumen at the top increased within 48 h, confirming the accumulation of the TSNR phase at that section. However, at the bottom, an increase in viscosity was observed due to TSNR absorbing maltene fraction components such as saturates and aromatics and increasing the composition of asphaltene and resin fractions with higher density and viscosity [17; 29; 39; 40; 42]. In addition, heavy fractions are disposed to the bottom, and light fractions are disposed towards the top during storage.