## 3 Results and Discussion
### Comparison of the TCT and BBCT Results  
Relationships between different test modes are commonly used in analyses of solid materials such as cement concrete. While Young's modulus should have the same value regardless of the test mode, the relationship between strength determined in simple tension and flexural test is approximately 1:2. While asphalt mixture strength relationships between different test modes were the subject of other studies [6; 57], in this study, the authors focused on relationships between stiffness moduli. In Figures 11-14, the results obtained from both tests are compared in various forms: stiffness curves for chosen temperatures, shifted stiffness curves as well as master curves.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Mixture Designation**} & \multirow{2}{*}{**Test Temperature T, \({}^{\circ}\)C**} & \multicolumn{4}{c}{**Richards Model Parameters (“Branching” Modification)**} \\ \cline{3-7}  & & **Max** & \(\beta\) & \(\gamma\) & \(\delta\) & \(\lambda\) \\ \hline \multirow{3}{*}{AC 11S} & \(>\)\(-\)10 & 4.766 & \(-\)9.066 & \(-\)0.428 & 1.327 & 0.000864 \\  & \(-\)10 \(\div-\)20 & 4.766 & \(-\)9.560 & \(-\)0.498 & 3.246 & 0.000206 \\  & \(<\)\(-\)20 & 4.766 & \(-\)10.471 & \(-\)0.848 & 3.713 & 0.000066 \\ \hline \multirow{3}{*}{AC 11S} & \(>\)\(-\)10 & 5.118 & \(-\)11.162 & \(-\)0.295 & 0.146 & 0.000090 \\  & \(-\)10 \(\div-\)20 & 5.118 & \(-\)11.835 & \(-\)0.368 & 3.234 & 0.000014 \\  & \(<\)\(-\)20 & 5.118 & \(-\)12.737 & \(-\)0.703 & 3.815 & 0.000004 \\ \hline \multirow{3}{*}{AC 11S} & \(>\)\(-\)10 & 4.764 & \(-\)10.941 & \(-\)0.429 & 1.358 & 0.000132 \\  & \(-\)10 \(\div-\)20 & 4.764 & \(-\)11.643 & \(-\)0.482 & 3.209 & 0.000026 \\ \cline{1-1}  & \(<\)\(-\)20 & 4.764 & \(-\)11.381 & \(-\)0.852 & 3.741 & 0.000025 \\ \hline \hline \end{tabular}
\end{table}
Table 7: Master curve parameters for the Bending Beam Creep Test (BBCT).  
Figure 10: Shift factor—WLF function: (**a**) BBCT; (**b**) TCT.  
Figure 11: Comparison of stiffness curves at temperatures of \(-10\)\({}^{\circ}\)C and \(-20\)\({}^{\circ}\)C.  
Figure 12: Comparison of shifted stiffness curves for AC 11S 50/70 MT, reference temperature: \(-10\)\({}^{\circ}\)C.  
Figure 13: Comparison of shifted stiffness curves for AC 11S 45/80-55 MT, reference temperature: \(-10\)\({}^{\circ}\)C.  
As shown in Figure 11, for the first 100 s the results obtained from both tests are similar, with higher values of stiffness modulus obtained from the TCT. For longer times of loading the results differ strongly, both in values and the shape of the curve. The stiffness ratio between the TCT and the BBCT for the first 100 s is around 1.5 (Figure 15b). In the case of longer times of loading, the relationship is in the range from 1.1 to 4.0, with no visible tendencies for specific types of bitumen. Comparison of the shifted stiffness curves (Figures 12 and 13) shows that for lower temperatures (<0 \({}^{\circ}\)C) higher stiffness values are obtained for the TCT. The relationship changes at temperatures higher than 0 \({}^{\circ}\)C, for which the values of stiffness modulus obtained in the BBCT are higher. The same is visible in the developed master curves (Figure 14), where the master curve derived from the BBCT has a \"flatter\" shape than the one from the TCT. The stiffness ratio between master curves is presented in Figure 15a. While the range of variability is lower (between 0.5 and 2.0), no direct relationships are visible in this case, as opposed to the case of stiffness curves for shorter times of loading. For the majority of the reduced time, higher values are obtained for the TCT.  
Figure 14: Comparison of master curves for all tested mixtures, reference temperature \(-10\)\({}^{\circ}\)C.  
Figure 15: Stiffness ratio (TCT versus BBCT): (**a**) master curves (**b**) stiffness curves at temperatures of \(-10\)\({}^{\circ}\)C and \(-20\)\({}^{\circ}\)C.