EFFECT OF ADDITION OF CARBOXYMETHY CELLULOSE (CMC) ON THE RHEOLOGY AND FLOW PROPERTIES OF BENTONITE SUSPENSIONS

In this work, bentonite suspension and mixtures containing 5 wt% of bentonite and 0.1 and 0.5 wt% of carboxymethyl cellulose (CMC) were investigated in terms of their rheology and hydrodynamic behaviour in pipe flow. All fluids exhibited non-Newtonian rheological behaviour that can be well described by the three parameters Herschel-Bulkley model. The axial velocity distribution was determined using ultrasonic pulsed Doppler velocimetry technique. In the laminar regime the flow parameters were predicted by integration of the constitutive rheological model used. In the turbulent flow, the Dodge and Metzner model was applied to fit the experimental data. The measurements of the friction factor showed a small amount of drag reduction for the pure bentonite suspension, whereas for the polymer-clay blend the drag reduction was more important.