Compressibility Behavior of Soft Clay Sediments

The oedometric path of normally consolidated unremolded clay sediments evolves, in the (log σ'_v - I_L) plane, toward a maximum point located above the C_c line (which characterizes the compression of material that has been remolded and reconstituted) highlighting "apparent" overconsolidation. Then, the curve tends to join the C_c line indicating the beginning of destruction (failure) of bonds between particles. This progressive rupture of bonds becomes complete when the path rejoins the remolded behavior in the high stress domain. This gradual transition, from unremolded behavior towards remolded behavior, has been investigated on marine sediments extracted from the Gulf of Guinea. Oedometric tests were performed on both natural (unremolded) clay samples and remolded ones. The study is supported by several microscopic observations with SEM (Scanning Electron Microscope) and mercury intrusion porosimetry.