As urban development requires groundwater table isolation of various historically polluted sources, the necessity of building effective, strong, flexible, and low-permeability cutoff walls raises the question of choosing optimum construction materials. Various authors have proposed water–cement–bentonite mixtures, which are often chosen by experience or a trial-and-error approach, using classical methods for testing (Marsh funnel) and representation of results (water–cement ratio, water–bentonite ratio). The paper proposes a more precise approach for assessing the viscosity and global representation of the three components. Moreover, this approached is exemplified with a better documented recipe for the choice of materials based on laboratory results. The representation of the mixtures was undertaken on a limited domain of a ternary diagram, where the components are given in terms of mass percentage. The derived properties (viscosity, permeability, and compressive strength) are presented on a grid corresponding to the physically possible mixtures. Based on this representation, the most efficient recipes are chosen. Because the mixture contains only fine aggregates, the viscosity was determined using a laboratory viscosimeter.

When studying the mechanical behavior of hydrated binders, it is necessary to prevent hydration contraction tensile failure in order to properly characterize the mechanical properties of the material. This is regulated by standards for cement testing, however for the case of water-cement-bentonite mixtures the influence of standard sand is not thoroughly studied. Since the hydration shrinkage and water suction is different for cement and bentonite, a range of eleven combinations of water-cement-bentonite were used at four sand percentages. The paper documented this influence ranging from a lower limit for which contraction cracking occurs up to an upper limit for which the presence of sand favorably interferes with the binder, the material being transformed from a binder paste into a mortar. It is documented the range of sand composition for which the variation of sand content prevents contraction, yet preserves binder properties. The laboratory testing consisted of viscosity evaluation during samples preparation, permeability and monoaxial compressive strength on samples cured in open atmosphere for 28 days.

Following the increased use of sealing structures built in order to isolate historically polluted sites or to repair infiltrations inflicted to the levee of dams, it emerged the need to choose the right materials for constructing barriers using cutoff wall technique. The objective of this paper is to assess the range of suitable material combinations (water, cement and bentonite) in order to attain proper compressive strength, permeability and ductility requirements of such a structure. This paper proposes the representation of various mixtures on a ternary diagram, where the components are used as mass percentages. Since the influence of excessive values of various components have on the physical and mechanical behavior of the samples, the study domain was limited to an area that represents feasible mixtures. The laboratory testing program aimed at studying the variation of the material ductility, expressed in terms of tangent elastic modulus at origin and maximum axial strain at failure. Other parameters previously studied (compressive strength, viscosity and permeability) are used for property correlation.