阳离子交换量对膨润土层间水化影响的试验研究

Experimental study of the influence of cation exchange capacity on hydration in interlayers of bentonite

膨润土因其具有强烈的膨胀性、极低的渗透性通常被用作防渗以及缓冲材料。阳离子交换量是影响膨润土的微观结构一个重要参数,进而会改变膨润土的膨胀性能以及水力和扩散特性。通过将改性后的锂基膨润土加热到不同温度,制备了一系列阳离子交换量逐渐降低的减电荷膨润土。采用核磁共振技术和X射线衍射技术获得了减电荷膨润土在不同含水率下的孔隙水分分布特征以及层间距变化,分析了阳离子交换量对膨润土层间水化的影响机制。研究表明,随着阳离子交换量的减小,可膨胀层的数量减少,导致膨润土的液限降低。根据核磁共振获得的横向驰豫时间T_(2)分布曲线提出了一个确定可膨胀层比例的初步方法,该方法获得的结果与可交换阳离子降低的比例是非常接近的。

Bentonite is commonly utilized as a waterproofing and buffering material due to its high expansibility and very low permeability.The cation exchange capacity is a crucial parameter that influences the microstructure of montmorillonite,thereby modifying its expansibility,hydraulic properties,and diffusion characteristics.Various montmorillonite samples with reduced cation exchange capacity were produced by heating lithium-modified bentonite at varying temperatures.By employing nuclear magnetic resonance and X-ray diffraction techniques,we acquired information on the distribution of pore water and interlayer spacing in montmorillonite with reduced cation exchange capacity under varying water content.Furthermore,we investigated the effect of cation exchange capacity on hydration in montmorillonite interlayers.The research demonstrates that a decrease in cation exchange capacity results in a reduction in the number of expandable layers,consequently lowering the liquid limit of bentonite.An preliminary approach for determining the proportion of expandable layers is suggested using the T_(2) distribution curve derived from nuclear magnetic resonance.The results from this method closely align with the proportion of reduced exchangeable cations.