Effect of Shear Deformation on Microfabric of Clay Using XRD Technique

The present paper deals with the impact of shear deformation on the geometric arrangement of particles within the soil specimen, which is termed as the microfabric of soil. A series of compression and extension lubricated end triaxial tests are performed on cylindrical specimens of Kaolinite clay with two extreme microfabrics; dispersed and flocculated, which are obtained using slurry consolidation technique. Flocculated microfabric has random orientation of particles within the soil mass having face-to-edge particle contacts; however, dispersed microfabric has parallel orientation of particles containing face-to-face particle contacts. When the specimen is subjected to large stress levels during its shear deformation, the particle orientation and the geometric arrangement within the soil specimen gets affected due to the force acting on the clay platelets. The variation in microfabric of soil before and after shear deformation process is evaluated by obtaining X-ray diffraction patterns of the clay specimen at three different locations using standard X-ray diffractometer. The discussion includes an analysis of the orientation of soil particles located at shear banding zones of the clay specimens, which may be useful for understanding the strain localization development in clays.