Abstract: Natural montmorillonite was studied by adapting ionic soil stabilizer (ISS) with different concentrations. The water vapor isothermal adsorption experiment was conducted on both raw and modified samples in the range of relative humidity (P/P0) from 0 to 0.95. By analyzing water adsorption velocity curves derived from adsorption results and d001 variation with P/P0, montmorillonite hydration mechanism was defined and association analysis of hydration-pore was implemented through void ratio variation with P/P0 that display the boundary relative humidity for pores in different scales adsorbing water. In addition, associated evolutionary mechanism of hydration-pore for montmorillonites conducted by ISS was indicated by different pore size analysis methods such as X ray diffraction (XRD), nitrogen adsorption and mercury injection test. The results show that, for calcium montmorillonite, the cations interact with water molecules firstly at the range of 00.8-0.9, weak adsorbed water gets into macropores sostenuto. Ionic soil stabilizer regulates the characteristics of adsorbed water by changing the physico-chemical parameters (cations and basal surface of crystal layer) to influence the hydration processes of pores.

Key words: hydration mechanism, pore structure, associated evolution mechanism, ionic soil stabilizer, montmorillonite