Geochemical influences on the rheological properties of four post-glacial marine clays

The remoulded strength, flow properties, and flocculation state of three Leda clays and one Norwegian marine clay were tested viscometrically.The clays were tested in a natural state, after organic destruction, and after partial amorphous extraction by citrate-dithionite. In the natural state, remoulded strength, flow behaviour, and flocculation state were found to be dependant on porewater salinity. After organic removal the materials still responded to salinity changes but exhibited decreased maximum, high-salinity strength. The removal of even the most soluble amorphous material caused a decrease in remoulded strength over the entire salinity - water content range investigated.The materials exhibited dilatant, Bingham plastic, and pseudoplastic behaviour in different portions of the water content - salinity field. Even partial removal of the amorphous component resulted in a shift in the salinity at which each flow type was evident. The salinity required to initiate systemic flocculation also increased following amorphous extraction.