碳酸钠污染重塑黏土微观结构的试验研究

,利用扫描电镜(SEM)观测浸泡试验制备的不同浓度的碳酸钠(Na2CO3)污染重塑黏土的微观结构,而后利用Matlab提取出污染重塑黏土的表观孔隙率和表观孔径分布,并进一步探讨Na2CO3对污染重塑黏土微观结构的改造机理。研究表明:经Na2CO3污染侵蚀后,重塑黏土的絮状结构遭到破坏,颗粒与孔隙重新分布,孔隙率显著降低;基于手动选取最佳阈值,利用Matlab提取的污染重塑黏土表观孔隙率随Na2CO3侵蚀程度的提高显著降低,表观孔径呈现出以大孔和中孔为主逐渐演化为以小孔和微孔为主的分布特征;Na2CO3通过与黏土颗粒的离子交换和吸附,与非碱金属阳离子和游离氧化物的化学反应以及与腐植酸的中和作用,实现对黏土微观结构的多元化改造。

EXPERIMENTAL STUDY OF MICROSTRUCTURE OF SODIUM CARBONATE CONTAMINATED REMOLDED CLAY

The microstructure of contaminated remolded clay was observed using scanning electron microscopy(SEM) after the preparation for the clay contaminated by sodium carbonate( Na2CO3) of different concentrations through immersion test. Subsequently,the apparent porosity and pore size distribution of the contaminated remolded clay were extracted by Matlab. Furthermore,the microstructure transformation mechanism of the contaminated remolded clay was investigated. The studies showed that the microstructure of the clay was transformed such as the destruction of flocculent structure,the redistribution of particles and pore,as well as the obvious reduction of pore porosity owing to the contamination and erosion of Na2CO3. Based on manual selection of the best threshold level,the apparent porosity of contaminated remolded clay extracted by Matlab was significantly decreased with the increase of Na2CO3erosion degree. Meanwhile,the apparent pore size distribution was characterized by the gradual evolution from a majority of macro and meso pores to minor and micro ones. Finally, the transformation of the clay microstructure maybe caused by the diverse effects of Na2CO3:the ion exchange and adsorption with clay particles,the chemical reaction with non-alkali metal cations and free oxide,as well as the neutralization with humic acid.