Strength, Permeability, and Compatibility of Slag-Cement-Bentonite Slurry Wall Mixtures for Constructing Vertical Barriers

The use of slag-cement-bentonite (slag-CB) slurry walls in the United Kingdom (UK) is widespread but only recently finding increased use in the United States (US). This paper presents the results of permeability, strength and compatibility tests on mixtures of slag-CB. Mixtures having 15 to 20% cementitious materials (with 75 to 80% slag replacement for Portland cement) were found to have the lowest hydraulic conductivity (2×10⁻⁸ cm/sec after one year of curing) and hydraulic conductivity was not affected by 0% to 60% slag replacement. Samples permeated with magnesium sulphate, which showed deterioration in immersion testing, showed little effect during permeation with magnesium sulphate in triaxial hydraulic conductivity testing over a period of 100 days. This indicates that cement-bentonite-slag material may be compatible with sulphates under confined conditions but not under unconfined conditions. Further, slag-CB was shown to be compatible with aniline and ethanol, organic contaminants that are known to degrade soil-bentonite.