## 2 Experimental Program
### Concrete Curing and Exposure Conditions  
The conditions of the construction site in Western China, where the temperature difference is large and concrete structures are eroded by saline soil, were simulated to achieve the curing conditions of the concrete in this study. Geotextiles saturated with water were used to cover the specimens, as shown in Figure 2, water was sprayed onto the specimens regularly every day for concrete curing, and the curing time was set to 14 d. After 14 d, the geotextiles were removed to expose the specimens to the environment of low humidity, large temperature difference, and saline soil erosion. The simulated environmental humidity was 35%, and the temperature was \(-\)5-40 \({}^{\circ}\)C. The temperature took 1 day as a cycle, including an 8 h heating period, 6 h high-temperature constant-temperature period, 5 h cooling period, and 5 h low-temperature constant-temperature period, as shown in Figure 3. The environmental condition of concrete eroded by saline  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{\begin{tabular}{c} **Physical** \\ **Properties** \\ \end{tabular} } & \multicolumn{2}{c}{\begin{tabular}{c} **Specific Surface Area** \\ **(m\({}^{2}\)/kg)** \\ \end{tabular} } & \multicolumn{2}{c}{\begin{tabular}{c} **Compressive Strength** \\ **3/28 Days (MPa)** \\ \end{tabular} } & \multicolumn{2}{c}{\begin{tabular}{c} **Flexural Strength 3/28** \\ **(MPa)** \\ \end{tabular} } & \multicolumn{2}{c}{\
\begin{tabular}{c} **Initial Setting** \\ **Time (min)** \\ \end{tabular} } & \multicolumn{2}{c}{
\begin{tabular}{c} **Final Setting Time** \\ **(min)** \\ \end{tabular} } \\ \cline{2-9}  & \multicolumn{2}{c}{**374**} & \multicolumn{2}{c}{**33/55**} & \multicolumn{2}{c}{**6.7/8.7**} & \multicolumn{2}{c}{**198**} & \multicolumn{2}{c}{**247**} \\ \hline Chemical & K\({}_{2}\)O & Na\({}_{2}\)O & Fe\({}_{2}\)O\({}_{3}\) & Al\({}_{2}\)O\({}_{3}\) & SiO\({}_{2}\) & CaO & SO\({}_{3}\) & MgO & Ignition loss (\%) \\ \cline{2-9} components & 0.82 & 0.43 & 4.27 & 8.38 & 24.53 & 56.93 & 2.73 & 3.80 & 3.60 \\ \hline \hline \end{tabular}
\end{table}
Table 1: The physical properties and chemical components of cement.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{
\begin{tabular}{c} **Indicators** \\ \end{tabular} } & \multicolumn{2}{c}{**Specific Surface Area (m\({}^{2}\)/kg)** & **Ignition Loss (\%)** & **Density (g-cm\({}^{-3}\))** & **Water Content (\%)** \\ \hline Fly ash & 287 & 4.60 & 2.30 & 0.50 \\ Slag & 429 & 1.24 & 3.10 & 0.25 \\ \hline \hline \end{tabular}
\end{table}
Table 2: The physical properties of fly ash and slag.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Groups**} & \multirow{2}{*}{**W/B**} & \multicolumn{2}{c}{\begin{tabular}{c} **Water** \\ **(kg/m\({}^{3}\))** \\ \end{tabular} } & \multicolumn{2}{c}{\begin{tabular}{c} **Cement** \\ **(kg/m\({}^{3}\))** \\ \end{tabular} } & \multicolumn{2}{c}{\begin{tabular}{c} **Fly Ash** \\ **(kg/m\({}^{3}\))** \\ \end{tabular} } & \multicolumn{2}{c}{\begin{tabular}{c} **Slag** \\ **(kg/m\({}^{3}\))** \\ \end{tabular} } & \multicolumn{2}{c}{\begin{tabular}{c} **Sand** \\ **(kg/m\({}^{3}\))** \\ \end{tabular} } & \multicolumn{2}{c}{\
\begin{tabular}{c} **Stone** \\ **(kg/m\({}^{3}\))** \\ \end{tabular} } & \multicolumn{2}{c}{
\begin{tabular}{c} **High-Range Water** \\ **Reducer (kg/m\({}^{3}\))** \\ \end{tabular} } \\ \hline OC & 0.40 & 160 & 400 & 0 & 0 & 699 & 1141 & 1.2 \\ F10S20 & 0.40 & 160 & 280 & 40 & 80 & 699 & 1141 & 1.0 \\ F15S15 & 0.40 & 160 & 280 & 60 & 60 & 699 & 1141 & 1.0 \\ F15S20 & 0.40 & 160 & 260 & 60 & 80 & 699 & 1141 & 0.9 \\ \hline \hline \end{tabular} Note: OC means ordinary concrete, F10S20 means concrete with fly ash of 10% and slag of 20%, F15S15 means concrete with fly ash of 15% and slag of 20%.  
\end{table}
Table 3: The mix proportion of concrete.