The rheological behaviour of calcium carbonate aqueous suspensions has been studied. The mixes were prepared at various solid volume fractions (0.316 to 0.426). The tests were carried out at 25°C by using the coaxial cylinder viscometer Rotovisko-Haake 20, system M5-osc., measuring device MV1P. Flow curves were determined by varying the shear rate from 0 to 1000 s-1 at constant shear acceleration. All systems show shearthinning flow behaviour. The experimental data of shear stress and shear rate were treated with rheological models of the both τ=f(γ̇) and τ=f(γ̇,Φ) type. In particular, as for the application of the τ=f(γ̇) models the Herschel-Bulkley one seemed to be the most effective for application to calcite suspensions; as regards the fitting of experimental data with the τ=f(γ̇,Φ) models, the Quemada equation was taken into consideration. Good correlations of the rheological parameters with pigment concentration were found.
