# Recycling Aged Asphalt Using Hard Asphalt Binder for Hot-Mixing Recycled Asphalt Mixture
## 2 Experiments
### Materials
#### 2.1.2 Mixture  
Research shows that the asphalt mixture with a finer gradation and a higher asphalt binder content has better low-temperature crack resistance and fatigue performance [21]. Therefore, for different RAP contents, different asphalt mixture gradations were designed in this paper. The greater the RAP content, the finer the asphalt mixture gradation. Three mixtures were designed and tested in this work: (i) the conventional hot-mix dense asphalt mixture using natural aggregates, AC-20; hot-mix recycled asphalt mixture designed with EME-20 (a high-modulus asphalt mixture originally recommended by the French industry) containing (ii) 50% reclaimed asphalt pavement (RAP), and (iii) 100% RAP. The designed aggregate gradation is shown in Figure 1.  
The RAP was collected from a pavement maintenance project; it was then sieved into three classifications: 0-8, 8-12, and 12-20 mm. The aged binder contained in the RAP was extracted from the aggregates according to ASTM D2172-05, and its properties are listed in Table 4. The gradation of three classifications was determined according to ASTM C136, and the results are shown in Figure 2. The gradation was then used in the recycled mixture design by adjusting the ratio of the three classifications. In addition, the asphalt content of the three RAP classifications was tested, and the results were 6.42% (0-8 mm), 3.21% (8-12 mm), and 2.05% (12-20 mm). The physical properties of the virgin and old aggregates are shown in Table 5. The produced hard asphalt (HA), made with 40% TLA and 60% virgin asphalt (VA) was used as the newly-added binder for EME-20850%RAP and EME-200%100%RAP. The performance of HA is listed in Table 6. Based on the Marshall test, the optimal asphalt contents for AC-20, EME-200%8 PAP, and EME-200%100%RAP were determined. Details are shown in Table 7.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Penetration at 25 \({}^{\circ}\)C (0.1 mm)** & **Softening Point (\({}^{\circ}\)C)** & **Ductility at 15 \({}^{\circ}\)C (cm)** & **Density (g/m3)** \\ \hline
27 & 57 & 21 & 1.44 \\ \hline \hline \end{tabular}
\end{table}
Table 4: The performances of aged asphalt binder extracted from reclaimed asphalt pavement (RAP).  
Figure 1: The aggregate gradation of the three designed mixtures.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Properties** & \begin{tabular}{c} **Limestone** \\ **Coarse** \\ \end{tabular} & \begin{tabular}{c} **RAP Aggregates** \\ **Fine** **Coarse** \\ \end{tabular} & \
\begin{tabular}{c} **Mineral** \\ **Fine** **Filler** \\ \end{tabular} &
\begin{tabular}{c} **Test** \\ **Method** \\ \end{tabular} \\ \hline Bulk-specific gravity (kg/m3) & 2751 & 2715 & 2720 & 2622 & 2648 & T0308 \\ Flat-elongated Particles (\%) & 11.4 & - & 13.5 & - & - & T0311 \\ Water absorption (\%) & 0.5 & - & 0.4 & - & - & T0308 \\ Crush value (\%) & 12.6 & - & 14.2 & - & - & T0316 \\ LA abrasion (\%) & 22 & - & 24 & - & - & T0317 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Physical properties of the aggregates tested according to JTG E42—2005.