[2D16-19] Material

[2D16] A Study on Thermodynamics of Swelling Stress of Bentonite

Acquisition of Thermodynamic Data of Interlayer Water of K-Montmorillonite in Consideration of Alteration

*Misato Endo¹, Haruo Sato¹ (1. Okayama Univ.)

Keywords:swelling stress, K-montmorillonite, thermodynamic data, interlayer water, relative humidity method

In this study, the authors prepared samples in which all cations in the interlayer of montmorillonite, were replaced with K⁺ ions, and obtained thermodynamic data on the interlayer water (the activity and the relative partial molar Gibbs free energy of water) as a function of water content using a relative humidity method. The swelling stress of bentonite was analyzed based on a thermodynamic model developed in earlier studies and thermodynamic data obtained in this study and compared with measured data. The activity and the relative partial molar Gibbs free energy of water decreased with decreasing water content in the region below about 15%. The calculated results occurred in the region of above 1.9Mg/m³ with montmorillonite partial density.