## 6 Conclusions  
With respect to cement-stabilized soil systems, this study formulated a combined microscopic analyzing method, based on thermodynamic modeling and the XRD technique, so as to further clarify the modification mechanisms of a commercial composite alkaline activator (JA) and sodium polynaphthalene sulfonate (PNS) on the dissolution and precipitation of reactants and products. The feasibility and advantages of applying thermodynamic modeling to cement-stabilized soil systems were discussed, with the main conclusions being the following:  
1. Thermodynamic modeling can be applied to the systems of cement-stabilized soils by complementing thermodynamic data with the dissolution equations of the soil minerals. This novel method employs pore solution data to quantify the saturation levels of the minerals of interest, thus revealing more insights into the development of the corresponding chemical reactions. Techniques such as XRD are encouraged to be combined with the novel model in order to comprehensively characterize the compositional minerals since the investigated aqueous species may not be sufficient.
2. The formation of pozzolanic products grows linearly with the OH\({}^{-}\) concentration of the pore solution, while that of cement hydrates is highly correlated to the dissolution equilibrium of Ca(OH)\({}_{2}\) and its complexes. The Ca(OH)\({}_{2}\) in the pore solution is undersaturated after 5 h due to its consumption by the soil minerals. CaOH\({}^{+}\) appears to be the main chemical speciation of the Ca species and participates in the corresponding chemical reactions, with higher saturation levels resulting in higher amounts of cement hydrates.
3. JA alters the performances of cement-stabilized soils through the dissolution of its compositional minerals. When the pore solution is undersaturated, the proper JA dose improves the OH\({}^{-}\) concentration within the pore solution, accelerates the dissolution of the raw materials and increases the saturation of the aqueous species, thereby improving the formation of the reaction products and the compressive strength of the specimen. However, limited by the dissolution equilibrium of Ca(OH)\({}_{2}\) and its complexes, the excessively dissolved OH\({}^{-}\) from excessive JA doses would inhibit the dissolution of cement linkers, which would result in the formation of CO\({}_{2-}\) containing hydrates and a reduction in the compressive strength.
4. The CaOH\({}^{+}\) saturation is increased by adding PNS since the PNS molecules adsorb preferentially on montmorillonite over the clinkers, thereby lowering the consumption of the Ca species. This behavior accelerates cement hydration but hinders the formation of pozzolanic products. Due to the inevitable adsorption of the clinkers, an excessive PNS addition would lower the acceleration of cement hydration. Nevertheless, the compressive strength of the cement-stabilized soils in the PNS series exceeded that of the plain specimen in this study since cement hydrates are primarily responsible for compressive strength.  
Conceptualization, F.X. and E.J.; methodology, F.X.; software, E.J.; validation, F.X. and E.J.; formal analysis, F.X.; investigation, H.W.; resources, W.Q.; data curation, Y.H.; writing--original draft preparation, F.X.; writing--review and editing, F.X., E.J. and. P.Z.; supervision, W.Q.; funding acquisition, F.X. All authors have read and agreed to the published version of the manuscript.  
This study was funded by the National Natural Science Foundation of China (grant No.: 52109161), the China Postdoctoral Science Foundation (grant No.: 2021M691630) and the National Key R&D Program of China (grant No.: 2021 YFB2600704).  
Not applicable.  
The authors declare no conflict of interest.