纳米碳酸钙对红黏土的影响及其作用机理分析

Effect and mechanism analysis of nano calcium carbonate on red clay

为研究纳米碳酸钙对桂林红黏土组分、力学强度及微观结构的影响,探索纳米碳酸钙-红黏土的改性机理,对改性后的红黏土进行了相关的室内试验。结果表明:从物质组成上,桂林红黏土的主要矿物有石英、高岭石、赤铁矿,氧化物中SiO2、Al2O3、Fe2O3共占76.73%,加入纳米碳酸钙后,红黏土的矿物、氧化物的含量均受到影响。宏观上,纳米碳酸钙使红黏土的黏聚力、内摩擦角、抗剪强度减小,同时也降低了塑性指数;微观上,红黏土土颗粒主要以粒团、叠片等形式搭建结构骨架。经过MATLAB数据处理可知,加入纳米碳酸钙后红黏土整体孔隙减小,且干密度越大,孔隙率和分形维数越小,结构越稳定。压汞实验反映出纳米碳酸钙使红黏土大孔隙减少,小孔隙增多。

In order to study the effect of nanometer calcium carbonate on composition, mechanical strength and microstructure of Guilin red clay and exploring the modification mechanism of nanometer calcium carbonate-red clay, related laboratory experiments were carried out on the modified red clay. The results indicate that the main minerals of Guilin red clay consist of quartz, kaolinite and hematite. The predominant oxides are SiO2, Al2O3 and Fe2O3, which account to 76.3%. After red clay is applied with nano-CaCO3, the content of clay minerals and oxides will change. Macroscopically, nano-CaCO3 reduces the cohesion, internal friction angle and shear strength, and also declines plasticity index. Microcosmically, the remolded red clay particles are mainly structured in a form of cluster and lamination. The data from MATLAB indicates that with nano calcium carbonate, the overall porosity of red clay decreases.As the dry density increases, the porosity and fractal dimension decline, and the structure is stabilized. Mercury injection test indicates that nano calcium carbonate reduces the macropores of red clay and increases small pores.