外掺剂对红黏土微观结构及脆性指数影响

为了研究外掺剂对红黏土的影响,对掺入氧化钙、氧化铝、氧化钙与氧化铝联合掺入的红黏土重塑样进行三轴不固结不排水试验;通过分析在不同外掺剂以及不同掺入率下改性红黏土的应力-应变曲线、抗剪强度峰值曲线,得出三种外掺剂对红黏土的力学性质的影响,并建立模型对红黏土脆性指数进行量化分析。采用场发射扫描电镜对改性红黏土的微观结构变化进行比对分析。试验结果表明:红黏土的强度随着氧化钙掺入率的增大而增大,氧化钙在显著提高红黏土强度的同时降低其脆性指数,导致其延展性变差;氧化铝的单独掺入对红黏土的力学性质影响甚微;氧化钙与氧化铝联合掺入能够提高红黏土的脆性指数,使红黏土的延展性能变好的同时提高了红黏土的强度。

Effect of external admixture on microstructure and brittleness index of red clay

In order to study the effect of external admixture on red clay, a tri-axial unconsolidated undrained test was carried out by adding calcium oxide, alumina and a red clay remolded sample of calcium oxide and alumina, and analyzed by different external admixtures and The stress-strain curves and shear strength peak curves of modified red clay under different incorporation rates were obtained. The mechanical properties of three external admixtures on red clay were obtained, and the model was used to quantify the brittleness index of red clay. The field structure scanning electron microscopy was used to compare the microstructure changes of the modified red clay. The results of comparative analysis show that the strength of red clay increases with the increase of the incorporation rate of calcium oxide. Calcium oxide decreases the brittleness index of red clay while decreasing the strength of red clay, leading to the deterioration of its ductility. The incorporation of alumina alone has little effect on the mechanical properties of red clay; the combined incorporation of alumina and calcium oxide can increase the strength and brittleness index of red clay and make the ductility of red clay better.