## 2 Materials and Methods
### SM-OGFC Sample Preparation  
SM-OGFC samples are prepared to determine the optimization of SM-OGFC with different asphalt-aggregate ratio, different compaction times, different mixing temperature and different silane coupling agent content. Due to the high specific surface of OSW, the silane coupling agent is not suitable for surface treatment of the OSW directly, so pre-mixing of silane coupling agent and the heated base asphalt is necessary for better mixing. Firstly, the silane coupling agent was mixed into  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Technical**} & \multicolumn{2}{c}{**Penetration**} & \multirow{2}{*}{**25 \({}^{\circ}\)C**} & \multirow{2}{*}{**Softening**} & \multirow{2}{*}{**Wax**} & \multirow{2}{*}{**Flash**} & \multirow{2}{*}{**Solubility**} & \multirow{2}{*}{**Density**} \\
**Parameters** & & & & & & & & \\ \hline Units & & 0.1 mm & cm & \({}^{\circ}\)C & \%\(\leq\) & \({}^{\circ}\)C & \%\(\geq\) & g\(\cdot\)cm\({}^{-3}\) \\ Test results & 27.5 & 81.3 & 132.6 & \textgreater{}130 & 44.2 & 18 & 340 & 99.9 & 1.003 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Technical parameters of ’Pan Jin’ asphalt.  
Figure 1: Oil shale waste (OSW) in a power plant in Jilin province China.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Physical**} & \multirow{2}{*}{**Apparent**} & \multirow{2}{*}{**Water**} & \multirow{2}{*}{**Cushing**} & \multirow{2}{*}{**Cohesion**} & \multirow{2}{*}{**Internal Friction**} & \multirow{2}{*}{**Optimum**} \\
**Property** & & & & & & & \\
**Density (g/cm\({}^{3}\))** & & & & & & \\
**Absorption (\%)** & & & & & & \\
the base asphalt at 160 \({}^{\circ}\)C to stir for 5 min. After pre-mixing, the asphalt with silane coupling agent, granites with grain size greater than 4.75 mm in gradation, OSW with grain size less than 4.75 mm in gradation and mineral powder with particle size less than 0.075 mm were mixed in the vacuum mixing pot. Finally, the SM-OGFC samples are formed through the compaction of mixture. The gradation of OGFC used in this paper is the most commonly used one in China, which is demonstrated in Table 3. The flowchart of preparation of the SM-OGFC is shown in Figure 2. Moreover, two types of OGFC were used for the performance comparison, a conventional OGFC mixture with 'Pan Jin' base asphalt (OGFC), and a modified OGFC with SBS modified asphalt (SBS-OGFC). All asphalt mixtures were specified based on Technical Specifications for Construction of Highway Asphalt Pavement in China (JTG F40-2004), and the optimum asphalt content was found to be 4.8% and 4.1% for the control mixture.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline Sieve (mm) & 16 & 13.2 & 9.5 & 4.75 & 2.36 & 1.18 & 0.6 & 0.3 & 0.15 & 0.075 \\ \hline Apparent density & 2.78 & 2.78 & 2.78 & 2.74 & 2.74 & 2.75 & 2.70 & 2.70 & 2.69 & 2.67 \\ Bulk density & 2.77 & 2.76 & 2.75 & 2.68 & 2.64 & 2.59 & 2.60 & 2.59 & 2.57 & 2.55 \\ \hline Gradation (\%) & 97.5 & 65 & 47.5 & 23.5 & 11.5 & 11.5 & 9 & 7.5 & 6.0 & 4.5 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Properties of aggregate and gradation of OGFC-16.  
Figure 2: The flowchart of preparation of the SM-OGFC.