Consolidation and expansion of a granular bed of superabsorbent hydrogels

Both consolidation and expansion properties of a packed bed of superabsorbent hydrogel particles under the action of the mechanical loads were investigated in various ionic environments using a KCl solution to clarify the role of the osmotic pressure of the solution on the deformation behaviors of hydrogel particles. A description of the consolidation process was accomplished through the use of either the modified Terzaghi model or a simplified computation method. As the concentration of KCl solution increased, the consolidation rate increased and the packed hydrogels became denser. The data were well analyzed based on the idea of the effective osmotic pressure of the solution. Moreover, in the expansion process of the compressed bed of hydrogel particles, it was determined that the secondary expansion effect known as the creep effect plays an important role on the expansion behavior. It was found that expansion proceeds more slowly than consolidation. (c) 2006 American Institute of Chemical Engineers AlChE J, 53: 129-137, 2007.