Pressure-induced Gel–Sol Transition in Bentonite Suspensions

Abstract

BY dilatometric measurements, Anderson, Leaming and Sposito¹ have recently shown that a reversible change in volume of about 2.4 × 10⁻⁴ per cent occurs during the sol–gel–sol transition of a thixotropic sodium bentonite suspension. The volume increases during gelation and decreases during subsequent liquefaction. Since in a bentonite suspension neither crystallization nor dissolution accompanies the sol–gel–sol transition, the volume change is unexpected and has been attributed by the authors to an increased structure formation induced in the water by the bentonite gel structure. Previously, Anderson and Low have shown that the density of water is lower in the vicinity of the mineral particles of a bentonite suspension².