## 2 Materials
### Mortar Mix Design  
The same PmB bitumen described in Table 1 was used for the production of the mortars. The CR and the limestone filler were the same used for the SMA mixture. In order to define the mortar grading distribution, the SMA grading curve, described in the previous paragraph, was normalized to the particle percentages below 2 mm. The total material passing the 2 mm sieve was considered as 100% and therefore the other sieves have been normalized. Consequently, the bitumen and CR percentages were calculated based on the aggregate weight. The normalized fine aggregates passing the 2 mm sieve (Table 2) was calculated as follows:  
\[\mathrm{PFAN_{i}}=\frac{\mathrm{TP_{i}}\text{-}100}{\mathrm{TP_{2 mm}}} \tag{1}\]  
where:  
* \(\mathrm{PFAN_{i}}\) is the normalized passing fine aggregate;
* \(\mathrm{TP_{i}}\) is the total passing for each sieve;
* \(\mathrm{TP_{2 mm}}\) is the total passing the 2 mm sieve. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Property** & **Unit** & **Characteristic Value** & **Standard** \\ \hline Penetration @25 °C & dmm & 25–55 & EN 1426 \\ Softening Point & °C & 70 & EN 1427 \\ Force Ductility test @10 °C & J/cm3 & 3 & EN 13589 \\ Dynamic Viscosity @160 °C & Pa-s & 0.4–0.7 & EN 12596 \\ Elastic Recovery @25 °C & \% & 80 & EN 13398 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Conventional properties of the original bitumen. At the same time, for the production of mortars with the correct mixture components' amounts, normalized dosages of bitumen, fine CR and limestone filler were needed. The following equations were adopted:  
\[\mathrm{B_{FA}}=\mathrm{B_{A}}\cdot\frac{100}{\mathrm{TP_{2 mm}}} \tag{2}\]  
\[\mathrm{R_{FA}}=\mathrm{R_{A}}\cdot\frac{100}{\mathrm{TP_{2 mm}}} \tag{3}\]  
\[\mathrm{F_{FA}}=\mathrm{F_{A}}\cdot\frac{100}{\mathrm{TP_{2 mm}}} \tag{4}\]  
where:  
* \(\mathrm{B_{FA}}\) is the bitumen percentage of fine aggregates;
* \(\mathrm{R_{FA}}\) is the rubber percentage of fine aggregates;
* \(\mathrm{F_{FA}}\) is the filler percentage of fine aggregates;
* \(\mathrm{B_{A}}\) is the bitumen percentage of total aggregates;
* \(\mathrm{R_{A}}\) is the rubber percentage of total aggregates;
* \(\mathrm{F_{A}}\) is the filler percentage of total aggregates. All the components of the mortar mixture were normalized as follows:  
* \(\mathrm{FA_{FA}}\) (i-j) is normalized fine aggregates retained between sieves (i-j) percentage (except for the filler);
* \(\mathrm{FA_{m}}\) (i-j) is the fine aggregates retained between sieves (i-j) percentage (except for the filler) on mortar. The single components were obtained through Equations (5)-(8). \[\mathrm{B_{m}}=\frac{\mathrm{B_{FA}}}{\sum\mathrm{FA_{FA}}(\mathrm{i-j})+ \mathrm{F_{FA}}+\mathrm{B_{FA}}+\mathrm{R_{FA}}} \tag{5}\]  
\[\mathrm{R_{m}}=\frac{\mathrm{R_{FA}}}{\sum\mathrm{FA_{FA}}(\mathrm{i-j})+ \mathrm{B_{FA}}+\mathrm{R_{FA}}+\mathrm{F_{FA}}} \tag{6}\]  
\[\mathrm{F_{m}}=\frac{\mathrm{F_{FA}}}{\sum\mathrm{FA_{FA}}(\mathrm{i-j})+ \mathrm{B_{FA}}+\mathrm{R_{FA}}+\mathrm{F_{FA}}} \tag{7}\]  
\[\mathrm{FA_{m}}(\mathrm{i-j})=\frac{\mathrm{FA_{FA}}(\mathrm{i-j})}{\sum \mathrm{FA_{FA}}(\mathrm{i-j})+\mathrm{B_{FA}}+\mathrm{R_{FA}}+\mathrm{F_{FA}}} \tag{8}\]  
The amount of limestone filler (\(\mathrm{F_{m}}\)), bitumen (\(\mathrm{B_{m}}\)) and CR (\(\mathrm{R_{m}}\)) were calculated using the described normalization method, as shown in Table 3. \begin{table}
\begin{tabular}{c c c} \hline
**Sieve Size [mm]** & **Total Passing [\%]** & **Passing [\%] Normalized [2 mm]** \\ \hline
10 & 100.0 & / \\
8 & 97.5 & / \\
6 & 82.8 & / \\
4 & 40.1 & / \\
2 & 24.8 & 100.0 \\
1 & 19.8 & 79.84 \\
0.5 & 16.8 & 64.74 \\
0.25 & 13.4 & 54.03 \\
0.125 & 10.9 & 43.95 \\
0.063 & 9.0 & 36.29 \\ \hline \end{tabular}
\end{table} 
Table 2: Normalized stone mastic asphalt (SMA) grading curve. The mortars production operations were fixed uniquely for every sample. Before starting the mixing, fine aggregates were stored in the oven at 160 \({}^{\circ}\)C in order to achieve dry conditions.