# Phase Separation Study on the Storage of Technically Specification Natural Rubber Modified Bitumen
## 3 Results and Discussion
### Storage Stability of TSNR-Modified Asphalt
Because of the limited amount and absorption of TSNR to saturates and aromatics, the asphalt phase still contains a high concentration of these compounds. As a result, the difference in density and viscosity between the two phases remains significant, and the two components are incompatible. The significant difference in density and viscosity between asphalt and TSNR accelerates the mobility of the TSNR phase during phase separation [6; 52; 53]. The saturate- and aromatic-rich TSNR phase accumulated at the top causes the asphaltene phase at the bottom to be deficient in saturate and aromatic content. Thus, the asphaltene phase will eventually increase the ratio of resin and asphaltene [42; 43]. The increase in resin and asphaltene ratio shifts the glass transition temperature (Tg) of asphalt higher [43]. This, in turn, results in higher density, viscosity, hardness, and softening point of the modified asphalt at the bottom. The softening point of 10% TSNR decreased significantly when compared to 8% TSNR (Figure 5). The modified asphalt with 10% TSNR has improved compatibility. The TSNR phase can absorb more saturates and aromatics, resulting in a decrease in the difference in softening points. The saturate- and aromatic-rich TSNR phase increases the density and viscosity of the mixture. Phase separation can be suppressed by reducing the density difference and increasing the viscosity of the mix [16; 41; 43]. This provides the advantage of stabilizing the TSNR phase in the mixture and obtaining better compatibility [52]. Increasing the viscosity of modified asphalt mixtures is critical for improving the storage stability of TSNR-modified asphalt. TSNR absorbs certain saturates and aromatics, producing asphaltene- and maltene-rich (resin-rich) asphalt phases. Increasing the proportion of asphaltene and maltene (resin) is essential for limiting the mobility of phase separation by increasing the mixture's viscosity. Limiting the TSNR phase's mobility in the mix can delay or slow the occurrence of coalescence and flocculation phenomena [6; 39; 52; 53]. In addition, the resin in asphalt plays an important role as a stabilizer of asphaltene and other components in asphalt [30; 39; 41]. Increasing the content of resin and asphaltene is the  
Figure 7: Illustration of TSNR coalescence and flocculation phenomenon. key to forming a stable colloidal structure and improving the compatibility of asphalt and TSNR components [39; 41]. The difference in softening point increased again at 12% TSNR (Figure 6). The modified asphalt mixture's high TSNR content causes an increase in softening point difference. The same phenomenon was observed in the modified asphalt with 10% TSNR as well as the modified asphalt with 12% TSNR. However, adding more TSNR to the mixture than is optimal accelerates the coalescence and flocculation processes. As a result, the density and viscosity differences between the TSNR and asphalt phases increase, accelerating phase separation [16]. Comparing Figures 4-6, it is found that the softening point trend of each asphalt section (top and bottom) increases as the TSNR content added to the modified asphalt increases. The increased softening point at the top as the TSNR content increases indicates that the glass transition temperature (Tg) is becoming larger. This has the advantage of increasing the thermal stability and viscoelastic properties of the modified asphalt at the top after phase separation [41; 42; 43]. In contrast to the top, at the bottom, the softening point increases with increasing TSNR content. This can occur because the asphalt-rich phase at the bottom loses many saturates and aromatics. As a result, the glass transition temperature (Tg) at the bottom increases, increasing the modified asphalt's softening point [41]. The increase in the softening point of modified bitumen results in increased thermal stability and improved viscoelasticity of the binder [41; 42; 43].