Instrumented indentation devices allow testing of materials at small scales (micro and nanoindentation). In this framework, IFPEN has developed a new indentation system under confining conditions: this is a lightweight tool called Mechanicalab, which can perform simultaneously uniaxial strain test and indentation tests with a 7mm diameter flat indenter. This paper describes the tests carried out on clayey silt (Transinne Kaolin, Belgium) under different moisture contents both with this new equipment and with standard geomechanical devices (triaxial tests and uniaxial strain tests). Furthermore, indentation tests are carried out with the Mechanicalab and a classical indentation device working under atmospheric conditions.

1 Introduction

In the field of oil production, standard indentation tests have been widely used in order to characterize the formations, especially the overburden because of a lack of cores for standard tests. Indentation tests can be carried out with a small amount of material, do not require a specific sample shape or size and are easy to operate. The results depend on the test method, especially the indenter geometry and indentation parameters.

Whereas standard indentation systems operate under atmospheric conditions, IFPEN has developed a new indentation device called Mechanicalab in order to investigate the behavior of materials under confining conditions. The system first performs a uniaxial strain test on the material and then flat cylindrical indenters are forced into the sample.

In this paper, we investigate the behavior of clayey silt by means of conventional and indentation techniques. The results will be discussed by comparing on one hand indentation tests with triaxial compressive tests, and, on the other hand, Mechanicalab experiments with standard indentation tests.

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