胶体氧化物对红黏土微观结构和胀缩性的影响

Effect of Colloidal Oxides on Microstructure and Swelling-ShrinkageProperty of Red Clay

红黏土中胶体氧化物与黏土矿物之间的交互作用是影响土体微观结构与胀缩性的主要因素。采用选择性化学溶解法除去原状红黏土中存在的胶体氧化物,通过胀缩性试验、粒度分析、压汞、SEM等方法,探讨了胶体氧化物对土体微观结构和胀缩性的影响。试验结果表明:胶体氧化物以包膜形式附着在黏土矿物表面;去除胶体氧化物后土体微观结构发生了显著变化,表现为包膜消失导致土体结构连结变差、团聚现象减弱,颗粒分散程度增大,微孔减小和小孔增加。此外,去除胶体氧化物后土体相对密度、最优含水率、最大干密度、液塑性、自由膨胀率、线缩率等物理参数皆有所减小。研究成果正确认识了红黏土特殊的物理特性,丰富了红黏土相关基础理论。

The interaction between colloidal oxides and clay minerals is the major factor affecting the microstructure,swelling,and shrinkage of red clay.In this paper,the colloidal oxides are removed by the selective chemical dissolution method.The effects of colloidal oxides on the microstructure and swelling shrinkage of red clay are explored via swelling shrinkage test,particle size analysis,mercury injection,and SEM.Results illustrate that the colloidal oxides adhere to the clay mineral surface in the form of an envelope.The removal of colloidal oxides significantly changes the microstructure of soil.Moreover,the disappearance of the coating leads to the deterioration of soil structure bonding,weakening of agglomeration,increase of particle dispersion,decrease of micropores,and increase of pores.In addition,physical parameters of soil(specific gravity,optimal water content,maximum dry density,liquid plasticity,free expansion rate,and linear shrinkage rate)decrease since the removal of colloidal oxide.The research findings offer scientific basis for correctly understanding the special physical characteristics and enriching related basic theories of red clay.