The aim of this research was to characterise the elastic properties of a clayey material Kaolinite K13 and its change during a mechanical loading. An experimental test system, based on the ultrasonic propagation method, was developed. The ultrasonic tests were performed on samples recovered after oedometric loading. The experimental approach consists in investigating, through acoustic local measurements, the evolution of the elastic parameters along the oedometric path. Measurement of wave velocities at different frequencies was performed using an insertion-substitution method. Afterwards, the dynamic elastic modulus deduced from the wave velocities was compared to the static modulus obtained in the oedometric test.