Membrane Behavior of Engineered Clay Barriers for Geoenvironmental Containment State of the Art

摘要

The state of the art with respect to semipermeable membrane behavior in engineered clay barriers commonly used in geoenvironmental containment applications is reviewed. The existence of membrane behavior can significantly enhance the containment function of clay barriers, via reduction in both advective (hydraulic) and diffusive (concentration) driven contaminant transport. Although the data are limited and exceptions do exist, the membrane behavior in engineered clay barriers is shown to increase with increasing bentonite content and/or effective confining stress, and with decreasing void ratio and/or concentration of simple monovalent salt (KCl) solutions. However, the use of salt solutions containing divalent cations, such as CaCl2, has been shown to adversely affect the existence of membrane behavior. Although significant advances have been made in terms of understanding semipermeable membrane behavior in engineered clay barriers, additional advances are required before membrane behavior can be relied upon to enhance the containment function of engineered clay barriers.