# A Numerical Study of Chemical Compatibility of GCLs
## 5 Conclusions  
The chemical compatibilities of GCLs were investigated using a COMSOL model. The mesoscopic mechanism of chemical compatibility was explored. The main conclusions were as follows:  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Literature** & \begin{tabular}{c} **Initial Particle** \\ **Size (\(d_{0}\))/mm** \\ \end{tabular} & \begin{tabular}{c} **Initial Mobile** \\ **Porosity (\(n_{0}\))** \\ \end{tabular} & \
\begin{tabular}{c} **Chemical** \\ **Solution** \\ \end{tabular} &
\begin{tabular}{c} **Ionic Strength** \\ **(mol/L)** \\ \end{tabular} \\ \hline \multirow{4}{*}{Chen [44]} & \multirow{4}{*}{1/0.3} & \multirow{4}{*}{0.5} & \multirow{4}{*}{-} & 0.0395 \\  & & & & 0.0968 \\  & & & & 0.048 \\  & & & & 0.178 \\  & & & & 0.755 \\ \hline \multirow{4}{*}{Katsumi [6]} & \multirow{4}{*}{0.075} & \multirow{4}{*}{0.4} & 0.2 M KCl & 0.10 \\  & & & 0.5 M KCl & 0.25 \\  & & & 1.0 M KCl & 0.50 \\  & & & 0.2 M NaCl & 0.20 \\  & & & 0.5 M NaCl & 0.50 \\  & & & 1.0 M NaCl & 1.00 \\  & & & 0.1 M CaCl\({}_{2}\) & 0.10 \\  & & & 0.25 M CaCl\({}_{2}\) & 0.25 \\  & & & 0.50 M CaCl\({}_{2}\) & 0.50 \\ \hline \multirow{2}{*}{Jo [48]} & \multirow{2}{*}{0.2} & \multirow{2}{*}{0.4} & 0.1 M KCl & 0.1 \\  & & & 0.01 M CaCl\({}_{2}\) & 0.06 \\ \cline{1-1}  & & & 0.04 M CaCl\({}_{2}\) & 0.12 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Experimental parameter of verification.  
Figure 9: Comparison of predicted and experimental values.  
1. The application of small bentonite particles and small porosity is an effective method to improve the chemical compatibility of GCLs. With the increase in the chemical solution concentration, the swelling of the bentonite particles would be suppressed.
2. From the mesoscopic view, the final mobile porosity and the final pore size are the key factors affecting the hydraulic conductivity of GCLs. When the ionic strength increased from low to medium, the changes in particle size, the final pore size, the final mobile porosity, and the hydraulic conductivity were obvious. However, further increased the ionic strength from medium to high, the changes of these parameters tend to be gentle, and the changes of hydraulic conductivity were not obvious.
3. Based on the numerical results, a theoretical model for predicting the hydraulic conductivity of GCLs in chemical solutions was developed. The hydraulic conductivity can be predicted by the ionic strength of the chemical solution, the initial mobile porosity, and the initial particle size.  
Paper writing-original draft and writing-review and editing, J.H.; methodology and formal analysis, R.S. and M.K.; Data curation, C.-X.C. and M.N. All authors have read and agreed to the published version of the manuscript.  
This study was supported by the National Natural Science Foundation of China (NSFC) (Nos. 51778353, 51978390); Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences (No. Z018007); China Scholarship Council (CSC 201906895014).  
Not applicable.  
The authors express their gratitude for this financial assistance. The authors also express their sincere gratitude to [PERSON], the former Dean and Hamilton Chair in Engineering, School of Engineering, University of Virginia, who offered valuable suggestions for this study.  
The authors declare no conflict of interest.