## 2 Materials
### Oil Shale Waste  
Oil shale waste (OSW) is an acidic inorganic material formed by oil shale after dry distillation or combustion. OSW has the characteristics of porosity and high activity. The oil shale waste selected in this paper is the waste residue generated after the combustion of the Huadian Longteng Power Plant in Jilin Province China. The color of oil shale waste is gray-brown, and it has a layered joint structure of shale and a large number of flake particles [38]. The technical parameters of oil shale waste are shown in Table 2.  
Oil shale waste is a barren raw material with a small amount of residual carbon, which is similar to volcanic ash. The main chemical composition of oil shale waste is SiO\({}_{2}\), Al\({}_{2}\)O\({}_{3}\), Fe\({}_{2}\)O\({}_{3}\), MgO, and CaO, while the remainder is mostly ash. In the waste, SiO\({}_{2}\) mainly exists in the form of quartz, and Al\({}_{2}\)O\({}_{3}\) mainly exists in the form of kaolinite. Oil shale waste has strong acidity, and the pH value of oil shale waste is generally around 3.5-4.5. The composition of oil shale waste is more complex, and the composition of oil shale waste in different regions is not equal. There are also some toxic and harmful substances such as chromium, lead, and cadmium in oil shale waste in some regions. The main chemical composition of oil shale waste used in this study is shown in Table 3. Table 3 shows that the oil shale waste still retains some of the characteristics of the rock, and its main component is SiO\({}_{2}\), which accounts for 55.38% of the total. This means that the oil shale waste can be used as a filler to reinforce bitumen. The other components are Al\({}_{2}\)O\({}_{5}\), Fe\({}_{2}\)O\({}_{3}\), MgO, etc., which indicates that the oil shale waste has a function. In conclusion, oil shale waste, like other silicon inorganic asphalt modifiers such as silica, diatomic, asbestos, etc., can be used for asphalt modification in terms of chemical composition [38]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Item** & **Unit** & **Test Results** & **Specification Requirement** & **Test Procedure** \\ \hline
15 \({}^{\circ}\)C density & g-cm\({}^{-3}\) & 1.003 & N/A & T 0603-2011 \\
25 \({}^{\circ}\)C penetration & 100 g, 5 s, 0.1 & 81.3 & 80–100 & T 0604-2011 \\  & mm & & & \\ Softening point & \({}^{\circ}\)C & 44.2 & \(\geq\)42 & T 0606-2011 \\
25 \({}^{\circ}\)C ductility & cm & \textgreater{}130 & \textgreater{}100 & T 0605-2011 \\  & Wax content & \% & \textless{}1.8 & \textless{}3 & T 0615-2011 \\  & Flash point & \({}^{\circ}\)C & 340 & N/A & T 0611-2011 \\  & Solubility & \% & \textgreater{}99.9 & \textgreater{}99 & T 0607-2011 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Technical parameters of AH-90 base asphalt. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Technical** & **Apparent** & **Water** & **Crushing** & **Cohesion** & **Internal** & **Optimum** \\
**Parameters** & **Density** & **Absorption** & **Value** & **Cohesion** & **Friction Angle** & **Water Rate** \\ \hline Unit & g/cm\({}^{3}\) & \% & \% & KPa & \({}^{\circ}\) & \% \\ OSW & 2.627 & 18.6 & 42.2 & 13.84 & 33.3 & 28.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Technical parameters of oil shale waste (OSW). \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Chemical Composition** & **SiO\({}_{2}\)** & **CaO** & **Al\({}_{2}\)O\({}_{5}\)** & **Fe\({}_{2}\)O\({}_{3}\)** & **MgO** & **Ash** & **Others** \\ \hline Percentage (\%) & 55.38 & 22.28 & 4.72 & 5.34 & 2.01 & 9.71 & 0.56 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Main chemical composition of OSW. The microscopic appearance of oil shale waste is shown in Figure 1. After magnifying observation, it was found that the surface of oil shale waste is rough, that oil shale waste has a large number of micron-sized pores, and the edge of the pores is surrounded by mossy and petal-like protrusions.