It was always believed that water is “squeezed” out of the
clay structure under pressure but physicists at Umeå University together with
German colleagues show that this appear to be not always true if excess of
liquid water is available around. The new findings are published in Angewandte
Chemie.
Clay minerals are among most common on the Earth and some of
the most important materials in the construction and building industry. Layered
structure of clays can easily be expanded if water is added. This phenomenon is
called swelling and it is explained by the insertion of water into the
inter-layer space of clays structures. Swelling affects all possible applications
of these materials and is important for example in sealing of natural oil
reservoirs as the hydrated clays are not permeable for oil.