# Experimental Study on Physical and Rheological Properties of Trinidad Lake Asphalt Modified Binder
## 3 Results and Discussion
### TLA Content Effect on Rheological Properties of Modified Binders
#### 3.2.1 Complex Modulus and Phase Angle
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{3}{c}{**Frequency Sweep Test**} & \multicolumn{3}{c}{**Creep Test**} \\ \cline{2-6}
**Binders** & \multicolumn{3}{c}{**Test Temperature [\({}^{\circ}\)C]**} & \multicolumn{3}{c}{**Test Temperature [\({}^{\circ}\)C]**} \\ \cline{2-6}
**(\% TLA)** & **40** & **50** & **60** & **40** & **50** & **60** \\ \hline
0\% TLA & 63,840 \(\pm\) 4210 & 8916 \(\pm\) 763 & 1740 \(\pm\) 36 & 57,832 \(\pm\) 4089 & 8769 \(\pm\) 1009 & 1682 \(\pm\) 105 \\
10\% TLA & 130,367 \(\pm\) 9649 & 15,510 \(\pm\) 1376 & 2865 \(\pm\) 165 & 117,026 \(\pm\) 4216 & 14,711 \(\pm\) 1400 & 2698 \(\pm\) 172 \\
20\% TLA & 186,383 \(\pm\) 11,031 & 23,063 \(\pm\) 1903 & 4118 \(\pm\) 318 & 166,109 \(\pm\) 11,294 & 22,312 \(\pm\) 1597 & 3965 \(\pm\) 295 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: ZSV of TLA-modified binders. Figure 8: Black curves of TLA-modified binders at (**a**) 40 \({}^{\circ}\)C; (**b**) 50 \({}^{\circ}\)C; (**c**) 60 \({}^{\circ}\)C.  
Figure 7: Complex modulus (G*) and phase angle (\(\delta\)) of TLA-modified binders. The high compliance of viscosity values between the calculated (i.e., based on the Cross model) and measured data ranging from 0.01 to 100 Hz is shown in Figure 9. Therefore, the ZSV values for the TLA-modified binders could be determined at zero shear conditions. The results show that the TLA modification of the base bitumen increased the ZSV value at a specific temperature. A decrease of the ZSV was revealed with the TLA content decrease and the test temperature increase (Figure 10). The highest ZSV increase was determined at 40 \({}^{\circ}\)C; more than two-fold ZSV increase was obtained for 10% TLA content and about the three-fold increase for 20% TLA comparing to the base bitumen. At the remaining temperatures, the relevant ZVS increases were lower: 1.7 and 2.5 at 50 \({}^{\circ}\)C and 1.6 and 2.4 at 60 \({}^{\circ}\)C, for 10% and 20% TLA, respectively (Figure 11). Figure 11: ZSV from the Cross model for various TLA content and test temperatures. Figure 9: Measured and calculated viscosities versus angular frequency on a log-log plot at (**a**) 40 \({}^{\circ}\)C; (**b**) 50 \({}^{\circ}\)C; (**c**) 60 \({}^{\circ}\)C.  
Similar results of ZSV as for frequency sweep test were obtained from creep test and are shown in Figures 12-14. In Figure 12, the creep curves for TLA-modified binders at the specific temperature are plotted. For each TLA content at the specific temperature, the sample has reached a steady-state in the last 15 min of the test. The TLA addition increased the viscosity stiffening effect of TLA, which was revealed by much smaller deformations at the same shear load 50 Pa. The stiffening effect of TLA depends on the specific test temperature. The higher the test temperature, the lower the stiffening effect of TLA and the greater increase in creep deformation obtained. The shape of creep curves is similar, which reveals the stiffening effect of TLA, not the modification of the binder character itself. Just as with the frequency sweep test, a proportional decrease of the ZSV was obtained with a decrease of TLA content and an increase of the test temperature (Figure 13). The highest ZSV increase was observed at 40 \({}^{\circ}\)C; the two-fold ZSV increase was obtained for 10% TLA content and slightly less than the three-fold increase for 20% TLA compared to the base bitumen. At the remaining temperatures, the relevant ZVS increases were lower: 1.7 and 2.5 at 50 \({}^{\circ}\)C and 1.6 and 2.4 at 60 \({}^{\circ}\)C, for 10% and 20% TLA, respectively (Figure 14).