Evaluation of the organization of the homoionic smectite layers (Na+ or Ca2+) in diluted dispersions using granulometry, microscopy and rheometry

S. Paumier (1, 2) , A. Pantet (1) , P. Monnet (1)

1 LEA - Laboratoire d'Études Aérodynamiques
2 HydrASA - Hydrogéologie, argiles, sols et altérations - FRE3114

Smectites are swelling clay materials with pronounced colloidal properties that are widely used in industry. These properties originate in the electrokinetic properties of the smectite layers and their linkage capacities. Thin layers may be dispersed or aggregated according to many parameters, such as concentration, particle size and morphology, exchangeable cation nature and chemical environment (pH, ionic strength). The literature usually provides general rules, like the sodium dispersion contains a lot of small units whereas the calcium dispersion contains a few large units. A volume of water molecules bound to the clay surface is considered as the immobile water phase that behaves like the solid phase obstructing the flow. The water immobilized around layers and trapped inside aggregates can not participate to the flow. In this study, we evaluated the volume occupied by calcium and sodium units inside the dispersion containing the immobile water phase. First, the smectite was cautiously extracted from a raw bentonite and its physicochemical properties were determined. A large quantity of extracted and saturated smectite (Na-smectite and Ca-smectite) was obtained. Second, the unit size and a shape

Domaines: Minéralogie; Mécanique des fluides [physics.class-ph]

S. Paumier, A. Pantet, P. Monnet. Evaluation of the organization of the homoionic smectite layers (Na+ or Ca2+) in diluted dispersions using granulometry, microscopy and rheometry. Advances in Colloid and Interface Science, 2008, 141 (1-2), pp.66 - 75. ⟨10.1016/j.cis.2008.04.001⟩. ⟨hal-01913474⟩