Solution Retention Capacity as an Alternative to the Swell Index Test for Sodium Bentonite
Lee, JM
Department of Civil Engineering, Colorado State University, Fort Collins, CO 80523

Shackelford, CD
Department of Civil Engineering, Colorado State University, Fort Collins, CO 80523

(Received 16 January 2004; accepted 22 June 2004)

Abstract
A new test, referred to as the solution retention capacity (SRC), is proposed as a potentially less tedious and quicker alternative to the swell index (SI) test (ASTM D 5890) for bentonite. The SRC represents the amount of a 50-mL solution retained in one gram of oven-dried bentonite after centrifugation at 2750 g, and the SRC values are reported in units of mL/g. The SRC for two sodium bentonites from geosynthetic clay liners measured using deionized water and solutions containing calcium chloride (CaCl₂) at concentrations ranging from 5 mM to 500 mM is compared with the SI for both bentonites and the same test liquids. In general, both SI and SRC decrease with increasing CaCl₂ concentration due to a decrease in the thickness of adsorbed layer of the bentonite particles. However, the SI is greater than the SRC, with SI falling in the range of 7.5 mL/2 g £ SI £ 30 mL/2 g and SRC falling in the range of 1.7 mL/g £ SRC £ 7.2 mL/g. The difference in the magnitudes of SI relative to SRC is attributed, in part, to the differences in the units (i.e., mL/2 g for SI versus mL/g for SRC) and the accelerations (i.e., 1 g in SI versus 2750 g in SRC) for the two procedures. Also, the SI includes the volume of the solid bentonite, whereas the SRC does not.

Keywords:
bentonite, Clay, geosynthetic clay liner, index properties, swell index

Paper ID: GTJ12520
DOI: 10.1520/GTJ12520

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Author Lee, JM Affiliation Department of Civil Engineering, Colorado State University, Fort Collins, CO 80523 Author Shackelford, CD Affiliation Department of Civil Engineering, Colorado State University, Fort Collins, CO 80523 Author Lee JM, Shackelford CD Title Solution Retention Capacity as an Alternative to the Swell Index Test for Sodium Bentonite Symposium , Committee on