The velocity profiles and volume concentrations of free water and the solids matrix of flowing pastes can be mutually determined independently via flow experiments in an NMR tomograph. This supplies direct proof of the relative displacement of free water in flowing pastes. The two phases can be distinguished with the help of NMR by their different magnetic relaxation times (T2). It is possible to measure the wall-slip of the two phases and, hence, to differentiate between the shear and slip shares of the total volumetric flow. When the evaluation of the flow experiments is based on a material law, the accompanying material functions can then be derived for pastes or suspensions from the velocity and concentration distributions. For example, as in the case of the fully-developed steady-state pipe flow, without any additional assumptions or corrections as is normally necessary for capillary rheometry. Through the use of NMR, it is possible to correlate the rheological features of the material in question, its flow behaviour and its flow-induced structural changes.