Effects of Exchangeable Cations on Hydraulic Conductivity of a Marine Clay

S. Narasimha Rao and Paul K. Mathew
Ocean Engineering Centre, Indian Institute of Technology, Madras-600 036, India

Abstract: A laboratory study of the hydraulic conductivity (HC) of a marine clay with monovalent, divalent and trivalent cations revealed large differences in HC. The exchangeable cations employed in this study are Na, K, NH4, Mg, Ca and Al in order of increasing valency. An interpretation of the results derived from consolidation tests suggests that HC is significantly affected by the valency and size of the adsorbed cations. An increase in the valency of the adsorbed cations leads to quicker rates of consolidation and higher HC, while, for a constant valency an increase in the hydrated radius of the adsorbed cations results in a lower rate of consolidation and HC. The reduction in HC was related to the dispersion and deflocculation of clay. Lower valency and higher hydrated radii of the exchangeable cations enable the double layer repulsive forces to predominate, thereby increase dispersion and defloccalation.

Key Words: Consolidation • Dispersion • Exchangeable cation • Hydraulic conductivity

Clays and Clay Minerals; August 1995 v. 43; no. 4; p. 433-437; DOI: 10.1346/CCMN.1995.0430406
© 1995, The Clay Minerals Society
Clay Minerals Society (www.clays.org)