  Since the discovery of graphene oxide (GO), the most accessible of the
precursors of graphene, this material has been widely studied for applications
in science and technology. In this work, we describe a procedure to obtain GO
dispersions in water at high concentrations, these highly dehydrated
dispersions being in addition fully redispersible by dilution. With the
availability of such concentrated samples, it was possible to investigate the
structure of hydrated GO sheets in a previously unexplored range of
concentrations, and to evidence a structural phase transition. Tentatively
applying models designed for describing the small-angle scattering curve in the
Smectic A (or L$_{\alpha}$) phase of lyotropic systems, it was possible to
extract elastic parameters characterising the system on the dilute side of the
transition, thereby evidencing the relevance of both electrostatic and steric
(Helfrich) interactions in stabilising aqueous lamellar stacks of GO sheets
