Effect of Flocculated and Dispersed Microfabrics on Mechanical Properties of Reconstitued Kaolin Soils

Abstract

Mechanical properties of kaolin clay and silt with different geometric arrangements of microfabric, namely being flocculated and dispersed, are investigated. The samples were prepared and consolidated to 100 kPa by reconstituting commercially available kaolin powder with different pore fluids. A series of Ko consolidated undrained triaxial tests with different effective vertical stresses and axial strain rates were performed on the kaolin specimens to study its behaviour in shear and subsequently its shear strength parameters. Compressibility of kaolin was explored through tests carried out using the one dimensional consolidation test. The results show that the arrangement of microfabric will affect the mechanical properties of kaolin. For the normally consolidated dispersed samples at 300 kPa effective vertical stress, when ‘peak’ deviatoric stress occurs, the shear resistance of kaolin has shown a continuously reduction (termed strain softening). However, flocculated and dispersed microfabrics under normal consolidation showed no distinct peak strength up to axial strain of 20.0%. Such observation is useful to relate to the clayey soils most likely found at the transition regions between river and sea, where they tend to behave more like a dispersed sample studied herein due to appropriate concentration of salt in the ambient pore fluids and the presence of cations sodium. The (dispersed) clayey soils at those areas also tend to experience strain softening than those (flocculated) clayey soils along the riverbank with fresh water.