Concentration diffusion, fluid flow and fabric changes are coupled phenomena in fine soils. Indeed, experimental results previously presented by the authors showed the presence of a pressure front advancing ahead of the diffusing high-concentration front in bentonite and kaolinite specimens. This note presents a simple analysis of diffusion–fabric-flow coupling, based on elementary double-layer repulsion and attraction. Model predictions adequately agree with experimental data. High specific surface, high initial void ratio, and low initial pore-fluide concentration increase the sensitivity of soils to changes in pore-fluid concentration and enhance the potential development of pore pressure fronts. Key words: coupling, diffusion, clay, pore pressure, interparticle forces.