# Physical and Mechanical Properties of Reclaimed Asphalt
## 4 Results and Discussion
### Triaxial Test Results  
#### 4.3.1 Resilient Modulus  
The estimation of \(\mathrm{M_{R}}\) values is based on the AASHTO T307-99 [49], also taking into account the international literature [52; 53]. Table 4 shows the final values of \(\mathrm{M_{R}}\), which correspond to the maximum axial loads (Smax) of all blends for each sequence of 100 cycles. Overall, the values of \(\mathrm{M_{R}}\) for each blend increase as the force is applied during the load cycles in each sequence. It is noteworthy that in blend E the highest value of \(\mathrm{M_{R}}\) occurs in the penultimate sequence. This could be due to the fact that blend E contains finer particles compared to the other blends and may need to be subjected to additional or higher  
Figure 5: CBR values for each blend. loading to achieve the highest degree of compaction between particles. The influence of the compaction process on the mechanical behavior has also been mentioned elsewhere [5]. Figure 6 shows the \(\mathrm{M_{R}}\)-\(\mathrm{S_{max}}\) curves for all blends. For each blend, the trend line was selected based on the highest and best fitted coefficient of determination R\({}^{2}\)[54; 55]. All follow a polyonymic equation, while only the equation for blend B is nearly linear. Blends A, C, D and E have a similar R\({}^{2}\) around 0.70, while blend B (10-90% RAP-VA) has an R\({}^{2}\) of 0.94. This--combined with the linearity of the equation for blend B--may not be a realistic condition for unbound materials, as they exhibit nonlinear behavior [50]. Moreover, the \(\mathrm{M_{R}}\) values of blend B are the lowest among the other blends, which was not expected since its CBR value is the highest. Accordingly, the addition of only 10% RAP to VA cannot explain such a reduction in the bearing capacity to this extent, since the other blends with a higher RAP content exhibited even higher \(\mathrm{M_{R}}\) values in each sequence than the VA blend. Therefore, it was decided to exclude blend B from the additional investigation in terms of the permanent deformation assessment. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**A**} & \multicolumn{2}{c}{**B**} & \multicolumn{2}{c}{**C**} & \multicolumn{2}{c}{**D**} & \multicolumn{2}{c}{**E**} \\ \cline{2-11}
**Sequence** & \(\mathbf{M_{R}}\) & \(\mathbf{S_{max}}\) & \(\mathbf{M_{R}}\) & \(\mathbf{S_{max}}\) & \(\mathbf{M_{R}}\) & \(\mathbf{S_{max}}\) & \(\mathbf{M_{R}}\) & \(\mathbf{S_{max}}\) & \(\mathbf{M_{R}}\) & \(\mathbf{S_{max}}\) \\
**No. ** & **(  
In addition, Figure 6 shows a vertical alignment of the measurements. This observation is due to the applied stress in each sequence, since the process follows a sequence of loading and unloading conditions. Therefore, some values of applied stress are almost the same. A similar up and down is observed in the values of \(\mathrm{M_{R}}\), but the range has a lower value, with the exception of blend B. Moreover, the increasing proportion of RAP in the RAP-VA blends leads to an increase in the \(\mathrm{M_{R}}\) value in each sequence. This could be due to the presence of asphalt which bonds the aggregates and the fact that the voids are filled with the finer particles of RAP. Finally, the observed results for the \(\mathrm{M_{R}}\) values seem to be reasonable and are in agreement with previous studies [19; 27; 39] in which it was observed that the \(\mathrm{M_{R}}\) parameters of the RAP-VA blends mainly have a value of 400 MPa and above. Possible differences could mainly depend on the quality of RAP material used in RAP-VA blends. Overall, all RAP-VA blends have a \(\mathrm{M_{R}}\) value greater than the pure VA value, given the last sequence and the end of the \(\mathrm{M_{R}}\) test. More specifically, the 20-80% RAP-VA blend (blend C) has the highest \(\mathrm{M_{R}}\) value of all the others, corresponding to 464 MPa. The 30-70% RAP-VA blend (blend D) follows with a slightly lower \(\mathrm{M_{R}}\) value of 454 MPa and the last one is the 40-60% RAP-VA blend (blend E) with a \(\mathrm{M_{R}}\) value of 415 MPa.