Migration of Interlamellar Water During Freezing and Thawing of Wyoming Bentonite

Abstract Homoionic, clay‐water pastes of Wyoming bentonite were studied at near freezing temperatures by X‐ray diffraction. On freezing, the initial high d(001) spacings of the lithium‐ and sodium‐bentonite pastes decreased, first to about 19A and at about −10C to 16A. When the temperature was raised the d(001) spacings of the frozen clays increased substantially; on melting, the d(001) spacings quickly expanded to their initial high values. The behavior of the hydrogen‐aluminum‐, potassium‐, and calcium‐bentonite was similar except that spacings greater than about 20A did not occur. All the normally observed diffraction maxima of ordinary ice were present after lattice collapse. No anomalous diffraction maxima suggesting the presence of ice having an unusual crystallographic structure were detected. Evidently, when bentonite‐water pastes are frozen all but two or three monomolecular layers of the interlamellar water migrates into the pore space to form ordinary ice. The remaining interlamellar water therefore must correspond to the “unfrozen” water of previous investigations.