Water inflow into clay, clay rock and clay-sulphate rock can trigger swelling phenomena. The swelling of clay-sulphate rock containing the mineral anhydrite causes large engineering problems in tunnelling and road construction in terms of floor heaves and destruction of the lining, posing a severe threat to important infrastructure. Recently, this swelling problem arose also in a different setting: The implementation of geothermal installations caused swelling ground with high uplift rates, leading to dramatic damage in the town of Staufen (Germany). The swelling of clay and clay rock has important implications for highly toxic waste disposal. Engineered barriers (i.e., the sealing and buffer elements) used in repositories play a major role in retarding any possible flow and transport of substances in the beginning of operation of the repository. Bentonites and their mixtures with granular materials have been often suggested as ideal candidates for this function. After that, natural barriers (i.e., the host rocks) will take over the role. In view of this, it is important to investigate the behaviour of the materials that have been proposed as sealing and buffer elements as well as the behaviour of the host rock, including their swelling behaviour.

The prediction of the swelling behaviour of clay, clay rock and clay-sulphate rock and the design of measures to minimize the risks associated with swelling are challenging, because the mechanisms and controls of the swelling are not yet sufficiently understood. Mechanisms and controls in swelling and their implications are very variegated and include complex and coupled thermo-hydro-chemo-mechanical processes. Therefore, a comprehensive assessment often requires interdisciplinary approaches.

The session encourages submissions from all geoscientific fields including geology, mineralogy, hydrogeology, geochemistry and geomechanics that address processes, controls and implications of swelling rock and swelling clay. All contributions are welcome dealing with fundamental research, laboratory and field experiments, modelling, applications and case studies. By bringing together research across disciplines, the session intends to stimulate scientific discussion and innovation to enhance our present knowledge of processes and controls in swelling rock and clay; and their implications for geoscientific planning of large-scale engineering projects.