The inter-scale behaviour of two natural scaly clays

This paper describes the results of an experimental investigation of the inter-scale behaviour of two natural scaly clays. These have been tested by means of a custom-made inter-particle loading apparatus, which has enabled their mechanical response to be studied in both compression and shearing. The main features of the micromechanical behaviour of these clays have been compared, focusing on the influence of their composition, and the results are compared with those obtained testing the same materials using other devices (triaxial and ring shear apparatus). The results have shown that, contrary to expectations, the surfaces of the scales are not residual shear surfaces and the inter-scale angle of shearing resistance is actually closer to critical state or post-peak angles measured in conventional tests.