Laboratory study of electrokinetic effects in complex natural sediments

The electrokinetic response to the application of direct current potential fields is examined in four sediments: natural and undisturbed glacial till, reconstituted glacial till, pure kaolinite and pure montmorillonite. Till samples contain abundant calcite and expandable smectite clays. The presence of calcite in till samples buffers the sediment and prevents the development of the low pH conditions seen in pure clay systems. Electroosmotic flow in undisturbed till is equivalent in both horizontal and vertical directions. The volume of electroosmotically driven flow in reconstituted till is relatively independent of the amount of clay minerals present. Electroosmotic efficiency of these sediments is an inverse function of the amount of smectite present. Pure montmorillonite samples exhibit color changes, shrinkage cracks, water loss and an increase in Fe(II) content upon application of a potential field. (C) 1997 Elsevier Science B.V.