Carnallite - the thermal and thermomechanical behaviour in a salt diapir considered as a final disposal site

The experimental studies suggest that thermally-induced release of water from the carnallite structure depends highly on pressure, and in particular on the water vapour pressure. It is inferred that release of small amounts of structurally-bound water acts to increase the vapour pressure within intercrystalline pore spaces. Deformation of carnallit is accompanied by significant changes of the rock microstructure. The relative importance of these mechanisms and processes depends on temperature and the presence or absence of intercrystalline brine. Increasing the temperature from 500 to 1000 decreases the creep stress factor. Release of small amounts of chemically bound water from the carnallite crystals may be due to local reduction of the intercrystalline water vapour pressure on grain surfaces at dilatant site. (DG)