## 1 Introduction  
Chemical treatment is a typical technique for soft soil stabilization in civil engineering and hydraulic scenarios, with cement being used as a common stabilizer [1]. The engineering performances, such as strength [2; 3], compressibility [2] and durability [4], of stabilized soils can be significantly improved compared to natural soft soils by adding cement. The regulation and enhancement of these performances have become the major motivations for current research and applications, which, to the best knowledge of the authors, normally consist of (1) investigating the performance modification effects of different admixtures and (2) exploring the kinetics of performance development. The admixtures for cement-stabilized soils are generally categorized as either mineral or chemical admixtures [5]. Fly ash [6], slag [7; 8] and silica fume [9] are the typical mineral admixtures and their modification effects and corresponding mechanisms have long been investigated and are well clarified. Regarding chemical admixtures, one common type comprises the alkaline activators R\({}_{2}\)O-SiO\({}_{2}\), ROH, R\({}_{2}\)SO\({}_{4}\), R\({}_{2}\)CO\({}_{3}\) (R = K or Na or 0.5 Ca) and combinations of these [3; 10; 11; 12]. It has been reported that the proper addition of alkaline activators not only causes an increase in the unconfined compressive strength (UCS), microstructural density, soil mineral pozzolanicity and the total amount of reaction products of cement-stabilized soils [3; 11], but also a reduction in their compatibility [3; 12; 13]. Another common chemical admixture is the superplasticizer naphthalene [14; 15; 16], which produces similar influences on UCS, microstructural density and the total amount of reaction products as the alkaline activators, but it conversely influences the compatibility and pozzolanicity of the soil minerals. These reviewed studies have mainly attributed their experimental observations to the accelerated effects of chemical admixtures on the reaction progress within the system. Moreover, by combining knowledge from the cement industry, [PERSON] et al. [15] proposed that the modification effects of naphthalene are derived from the inhomogeneous adsorption of superplasticizer molecules on the different components of cement-stabilized soils. Notably, the soil types have varied among the reviewed literature, but the corresponding impacts on the modification effects of the admixtures have not been fully considered. Meanwhile, some of the literature has reported that the UCS reductions in cement-stabilized soils are caused by the improper addition of both alkaline activators [3] and the naphthalene superplasticizer [17], but the reasons for this have not been clearly addressed. Regarding the kinetics of performance development, it is widely accepted that cement-stabilized soils share the basic chemical mechanisms of dissolution and precipitation with cementitious materials, such as mortar and concrete [4; 18; 19; 20]. Knowledge [21] from cementitious materials has stated that after contact with water, the clinkers initially dissolve to form supersaturated aqueous phases and the hydrates subsequently precipitate from the solution. Meanwhile, by formulating a thermodynamic model, the chemical states of the dissolution and precipitation of certain compositional minerals within cementitious materials can be quantified by the corresponding saturation level (i.e., saturation index, which is denoted as _SI_) with respect to the pore solution [20; 22], which has provided profound insights into the multicomponent systems of cementitious materials. In addition to chemical state quantification, thermodynamic modeling has been successfully employed to predict the time-dependent phase assemblage of cementitious materials [20; 23] and assess their interactions with the environment [20; 24]. Though the thermodynamic method has been successfully applied to cementitious materials, it has not been systematically extrapolated to cement-stabilized soils.