Phenomenological analysis and physical interpretation of the reflection coefficient of clays

The reflection coefficient, also known as the chemico-osmotic efficiency co-efficient, is commonly measured in order to quantify the ability of clays to act as semipermeable porous media. However, it should be pointed out that this parameter is not a soil property, but it rather represents the soil response to hydraulic and chemical stresses, so that it depends on which test is used and may vary significantly when the clay void ratio, the specimen preparation method and/or the chemical composition of the pore solution are changed. A physically sound model is used to assess the flow mechanisms that govern the experimental determination of this parameter, considering also the effects of clay fabric.