Variation of fabric anisotropy of kaolinite in triaxial loading

By measuring electrical conductivity in two perpendicular directions, the variation of fabric anisotropy of kaolinite is determined during one-dimensional (K-o), anisotropic (sigma(1)/sigma(3) = constant), and isotropic (sigma(1)/sigma(3) = 1) consolidation tests. To verify the validity of test results, the fabric anisotropy is determined at selected stages of loading by analyzing electron micrograph images of vertical and horizontal sections of parent specimens. The results from the two independent techniques are in agreement with each other. The results reveal aspects that can aid in the process of constitutive modeling of clays. In general, it is found that an isotropic consolidation loading or an anisotropic consolidation loading in extension, which causes rotation of principal strain directions, decreases the fabric anisotropy developed during prior K-o consolidation. The initial fabric anisotropy, however, cannot easily be erased or reversed by such a loading.