This paper presents preliminary results on the collapse response of an artificially prepared sand-silt mixture in a hollow cylinder apparatus. The wetting stage is performed under constant mean and deviatoric stresses but at different intermediate principal stresses (controlled through the principal stress parameter b = (s2- s3)/( s1- s3)). Properties of the mixture are first described to complement its hydro-mechanical information. The preliminary results seem to indicate that collapse is larger when the intermediate stress coincides with the minor one.