Effects of micro structure changes on the macro behaviour of Istanbul (Turkey) clays exposed to landfill leachate

► High potassium content and alkalinity lead to illitisation of smectite stacks. ► Ion exchange reactions cause disintegration in the crystal structure of smectite-illite mixed layer mineral. ► Mineral disintegrations and particle re-alignment lead to increase of permeability and decrease of attenuation capacity of mineral liners. ► In case of reusing old unlined landfills, changes in the micro structure of underlying clays may lead to settlement problems.