# Effect of Nano Hydrolcite on the Aging Resistance of a High Binder Content Stone Mastic Asphalt
## Materials and Methods
### Methods  
The control and modified SMA 8 were produced and compacted in laboratory. Asphalt mixture production was conducted in a 30-L horizontal axis laboratory mixer, conforming to EN 12697-35 [40]. Cylindrical specimens (approximately with diameter of 101.6 mm and height of 63.5 mm) were compacted using the impact compactor, according to EN 12697-30 [41], applying 50 blows on each side. Prismatic specimens (approximately 400 mm \(\times\) 300 mm \(\times\) 50 mm) were compacted using the roller compactor, according to EN 12697-33 [42]. Prismatic specimens 400 mm \(\times\) 50 mm \(\times\) 50 mm were obtained by sawing the 400 mm \(\times\) 300 mm \(\times\) 50 mm specimens. Regarding test methods, Table 3 lists the parameters evaluated in the laboratory study. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Property/Type of Test** & **Test Standard** & **Parameter** & **Unit** & **Value** \\ \hline \multirow{4}{*}{Marshall method} & \multirow{4}{*}{EN 12697-34} & Binder content & \% & 7.5 \\  & & Stability & kN & 6.7 \\  & & Flow & mm & 3.2 \\  & & Marshall Quotient & kN/mm & 2.1 \\  & & Porosity & \% & 4.9 \\ \hline Skid resistance & EN 13036-4 & Pendulum test value (PTV) & n.a. & 58 \\ \hline Surface macrotexture & EN 13036-1 & Mean texture depth (MTD) & mm & 1.2 \\ \hline \multirow{4}{*}{\
\begin{tabular}{c} Permanent \\ deformation \\ \end{tabular} } & \multirow{4}{*}{EN 12697-22} & Rut depth in air (RD\({}_{\text{air}}\)) & mm & 3.9 \\  & & Proportional run depth in air (PRD\({}_{\text{air}}\)) & \% & 7.5 \\  & & Wheel-tracking slope in air (WTS\({}_{\text{air}}\)) & mm/\(10^{3}\) cycles & 0.286 \\ \hline Indirect tensile strength & EN 12697-23 & Indirect tensile strength (ITS) & MPa & 2.368 \\ \hline Water sensitivity & EN 12697-12 & Indirect tensile strength ratio (ITSR) & \% & 95 \\ \hline Stiffness & \multirow{2}{*}{EN 12697-26} & Stiffness modulus & MPa & 4565 \\  & & Phase angle & \({}^{\circ}\) & 22.7 \\ \hline \multirow{4}{*}{
\begin{tabular}{c} Resistance to fatigue \\ (at 20 \({}^{\circ}\)C, 10 Hz) \\ \end{tabular} } & \multirow{2}{*}{EN 12697-24} & \(\varepsilon_{5}\) & \(\mu\)m/m & 403 \\  & & Slope of the fatigue line & n.a. & \(-5.02\) \\ \hline \hline \end{tabular} n.a.—not applicable.  
\end{table} 
Table 1: Properties of the control mixture. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Binder** & **Penetration** & **Softening Point** \\  & \(\times\)**10\({}^{-1}\) mm** & \({}^{\circ}\)C** \\ \hline Control & 52.5 & 90.0 \\ Modified & 47.1 & 93.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Properties of control and modified binders. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Property** & **Test Standard** & **Parameters** & **Mixture Conditioning** \\  & & **Unaged** & **Aged** \\ \hline Skid resistance & EN 13036-4 & Pendulum test value (PTV) & \(\surd\) & \(\times\) \\ \hline Surface macrotexture & EN 13036-1 & Mean texture depth (MTD) & \(\surd\) & \(\times\) \\ \hline Indirect tensile strength & EN 12697-23 & Indirect tensile strength (ITS) & \(\surd\) & \(\surd\) \\ \hline Water sensitivity & EN 12697-12 & Indirect tensile strength ratio (ITSR) & \(\surd\) & \(\surd\) \\ \hline Stiffness & EN 12697-26 & Stiffness modulus & \(\surd\) & \(\surd\) \\  & & Phase angle & \(\surd\) & \(\surd\) \\ \hline Resistance to fatigue & EN 12697-24 & Fatigue lines & \(\surd\) & \(\surd\) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Test methods. The surface characteristics of the control and modified asphalt mixtures were evaluated on prismatic specimens (300 mm \(\times\) 400 mm \(\times\) 50 mm) compacted using the roller compactor, as this compaction method is more similar to actual field compaction. The skid resistance was evaluated using the pendulum test [43] and the mean texture depth was evaluated using the volumetric patch technique [44]. Regarding mechanical performance, the control and modified SMA 8 were tested for indirect tensile strength, water sensitivity, stiffness and resistance to fatigue.