Physicochemical characterisation and flow properties of some bentonite muds

In civil engineering technologies, bentonites mixed with water are commonly used as bentonitic mud. The choice and the definition of criteria for mud selection are a difficult problem for industrials. This paper proposes a data set obtaining from the physicochemical and rheological investigation of 16 different commercial bentonites. Several analytical techniques are used to determine the mineralogical composition of those powders including X-ray diffraction, DTA and chemical analysis. Physical parameters such as particle size, specific surface area, swelling index, cationic exchangeable capacity and exchangeable bases are also studied. The viscosity of the mud is tested, thanks to the classic Marsh funnel viscometer and the rheological properties (yield stress, plastic viscosity and thixotropy) are measured by a high-resolution rheometer (Stresstech). Mineralogical data show that the bentonite appellation covers a very large variety of materials. Even if the main mineral is smectite, the global analysis of the powders shows that commercial bentonites contain secondary minerals, salts and sometimes polymers. Rheological data obtained for established flow allow to define two families of bentonite mud which difference seems to be due to industrial treatments. In fact, each bentonite develops its own behaviour depending on multicriteria. The results from this study show that it is necessary to characterize the mud from mineralogical and rheological points of view and to take into account, the nature of the excavated soils in order to choose the best bentonite. (C) 2003 Elsevier B.V. All rights reserved.