离子固化剂改性蒙脱土水合-孔隙关联演化机制

Associated evolutionary mechanism of hydration-pore for montmorillonite modified by ionic soil stabilizer

以天然钙蒙脱土为研究对象,采用不同浓度的离子固化剂对其进行改性处理,开展素土与改性蒙脱土在相对湿度(P/P_0)0～0.95区间的水汽等温吸-脱附试验,通过吸附速率曲线、晶层间距d001值变化曲线分析蒙脱土水合机制,并采用蒙脱土孔隙比变化曲线关联分析水合-孔隙演化规律,提出不同尺度孔隙吸附水的界限相对湿度区间。在此基础上,基于X射线衍射(XRD)、氮气吸附以及压汞试验对离子固化剂改性蒙脱土水合过程的孔隙分布特征进行验证分析。试验结果表明:对于钙蒙脱土,0<P/P_0<0.45～0.55时,为层间阳离子水合作用阶段,伴随着微孔(层间)扩展;0.45～0.55<P/P_0<0.8～0.9时,为蒙脱土矿物内外表面(晶层基面)吸附作用阶段,水分主要吸附于蒙脱土叠聚体间的介孔;P/P_0>0.8～0.9时,黏土颗粒表面持续吸附弱结合水,此时大孔内逐渐充填水分。离子固化剂通过改变蒙脱土的微观物理化学性质(阳离子与晶层基面)调控其吸附水特性,进而影响不同尺度孔隙的吸附水过程。

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 0P/P00.45-0.55, accompanying with the expansion of micropores（interlamellar space）. Followed by hydration on the internal and external surfaces of minerals at the range of 0.45-0.55P/P00.8-0.9, water mainly adsorbs into the inter-particular mesopores. With further hydration sequence when P/P00.8-0.9, 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.