Novel bentonites for containment barrier applications

Sodium bentonite (Na-bentonite) commonly is used in geoenvironmental containment barriers to control liquid flow and contaminant migration, but is known to be hermodynamically unstable in environments where multivalent cations are present. As a result, a host of novel, chemically-modified bentonites designed for improved resilience have been developed. The objective of this paper is to illustrate selected properties of some of these bentonites being considered for containment barrier applications. The bentonites considered in this paper include Na-bentonite polymerized with acrylic acid (bentonite-polymer anocomposite, or BPN), Na-bentonite amended with sodium carboxymethyl cellulose (HYPER clay), and a propylene carbonate modified Na-bentonite (multiswellable bentonite, or MSB). Engineering properties of the novel bentonites relevant to two specific types of barriers (i.e., cutoff walls and geosynthetic clay liners) are compared and contrasted with those of natural Na-bentonites. The results illustrate the potential for improved hydraulic performance of barriers containing the novel bentonites. However, further research is needed elucidate the mechanisms responsible for differences in behavior and performance among these bentonites