The flow properties of alumina powder mixtures have been investigated using shear tests on a powder rheometer. The evolution of the flow index, ffc, as a function of the powder mixture composition show that all the points form a single curve whatever the pre-shear consolidation stress value adopted, the mixing conditions and the preconditioning of the powder bed (relative humidity) before the tests. It has been also shown that the flow properties of the mixtures are controlled by the competition between the inter-particle interaction forces (Van der Waals and capillary contributions) and gravity via the Bond number. (C) 2019 Elsevier B.V. All rights reserved.