Thermodynamic model for predicting mineral phase distribution in cement-stabilized kaolinite systems

In this study, a new method based on the chemical thermodynamic model was proposed to quantitatively predict the phase distribution in cemented soil. The commercial kaolinite with simple phase composition was selected, and a series of cemented kaolinite samples were prepared by adjusting the cement content, binder-water ratio, and NaOH/KOH doses. The samples were then characterized qualitatively and quantitatively using X-ray diffraction (XRD) and 29Si-nuclear magnetic resonance (29Si-NMR) techniques, respectively. Then, a thermodynamic model of cemented kaolinite was constructed using the GEMS software and the chemical thermodynamic database Cemdata18, simulating the evolution of mineral distribution in cemented kaolinite under different cement contents and alkali activation conditions. The simulation results were compared and analyzed with the micro-characterization results. The research indicates that the thermodynamic model can reliably predict the mineral distribution evolution in cemented kaolinite. Meanwhile, cement and alkalis have varying maginitude of "dissolution-polymerization" effects on the high polymerization chemical groups in soil, and the type of alkali significantly affects the depolymerization of clay minerals and the type and structural characteristics of the polymerization products.