This paper describes the contribution of rheology to obtaining a better knowledge of structural network established by smectites in water. Physico-chemical and rheological properties of two industrial bentonitic fluids (Volclay and Wyoming) are explored with two criteria: concentration (20g/l to 60g/l), and granulometric fraction (total powder, < 2μm). Suspensions made with distilled water generally exhibit the properties of non-newtonian fluid which are measured by a high-resolution rheometer (Stresstech). Thixotropy, shear shinning, and yield stress are the main characteristics of these viscoelastic fluids. Flow tests are undertaken with very accurate procedures to guaranty good reproducibility. As a preliminary, several analytical techniques were used to determine the mineralogical composition including X ray diffraction, infrared spectrometry, and chemical analysis. Rheological data show the creation of a macroscopic network which is very influenced by each of the previous criteria. Results allow the determination of rheological parameters of a Herschel Bulkley law which have permitted the prediction of steady flow in circular pipes for Wyoming bentonite (Besq et al., 2000).
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