An experimental method of measuring the confined compression strength of geomaterials

Knowledge of the behaviour of geomaterials under confined compression is a pre-requisite for any analysis of their ballistic performance. This study proposes an experimental method of determining the spherical and deviatoric behaviour of these materials under high pressure. Known as the ‘quasi-oedometric compression test’ it consists of compressing a cylindrical specimen tightly enclosed in a thick confinement vessel. The principles of these quasi-oedometric tests are given first, and the steps taken for their execution, together with an examination of the steel used for the confinement vessel. An original way of analysing the data of the test is presented and validated by numerical simulations. These calculations provide valuable information about the influence of the interface product introduced between the vessel and the specimen, and that of friction. Tests are then presented with specimens of aluminium alloy to validate the experimental set-up and the method of analysis. In addition, quasi-oedometric compression tests of cement based material, with and without particles, illustrate the opportunities offered by this testing method, and show that its deviatoric strength and compaction law are significantly improved by ceramic granulates addition.