Physical and rheological properties of the Chorfa dam mud: dependency on solids concentration

Abstract

Abstract The main purpose of this study is to determine the mud rheological properties of the Chorfa dam (region of Mascara, Algeria) and to propose a rheological model that describes mud flow behavior. This study helps on one hand to give a better understanding of fine sediment transport dynamics in the dam, as well as contributing to reduce the dredging costs, and on other hand to valorize dredged sediments in road construction. Rheological measurements were conducted using an Engler viscometer and a Haake RS 600 rheometer. Mud samples were prepared with purified water at a range of solids concentration varying between 5.0 and 32.5%. Besides, the physical, chemical and mineralogical characteristics of the Chorfa dam’s mud and the rheological tests were presented and the effect of solids concentration on mud viscosity was studied. The results indicate that the Chorfa dam’s mud showed a non-Newtonian behavior for solids concentration higher than the critical solids concentration, and the apparent viscosity increases with increasing solid concentration at different shear rates. In addition, for a fixed concentration, the apparent viscosity decreases with increasing shear rates, which approves the shear thinning behavior of the Chorfa dam’s mud. Fitting results of four rheological models (Bingham Plastic Model, Ostwald–de Waele (power law), Herschel–Bulkley and Casson) to the experimental data were presented. Hence, the Ostwald–de Waele model was the best fitting model for mud samples.

Keywords

• Mud
• Solids concentration
• Apparent viscosity
• Rheometer
• Rheological model