Application of the nanoindentation technique for the characterization of varved clay

Abstract

Nanoindentation is a test carried out in a small scale, during which a rigid indenter (of known hardness and geometry) is pressed into the tested material. The results of the test are the load and unload curves, from which the harerial characterized by high heterogeneity (like soil – composed of grains and particles of different size and mineral composition), the use of multiple nanoindentation on a predefined grid (Grid Indentation Technique) is reasonable. It allows for the determination of the morphology of the material in a selected scale of observation. In the study, nanoindetation tests were performed on samples of varved clay - soil composed of two alternately arranged layers - occurring near the city of Bełchatów in central Poland. Due to the layered structure of the material, the tests were carried out for both layers separately. The outcomes show that there are significant differences in the values of their mechanical properties. Application of the deconvolution technique also allowed for the estimation of the number of components of both layers and their mechanical properties.

Keywords

• nanoindentation
• hardness
• elastic modulus
• morphology, git
• deconvolution
• varved clay