Debris flows or mudflows are complex natural hazards, because they are able to occur in different states. The baseline is a highly concentrated mixture of sediment and water mostly with a high content of fines. In debris flow research, the physical parameters and the releasing mechanisms are of great interest. It was found that non-hydrostatic fluid pressure can build up and dissipate during a debris flow event, and that this excess fluid pressure has a strong influence on the flow and deposition behaviour of debris flows. Therefore, this master thesis investigates the influence of mixture composition on the dissipation of non-hydrostatic fluid pressures. The basic principle for the following analysis is the one-dimensional consolidation theory. For the following experiments, two different types of clay (kaolinite and smectite) are used to prepare eight different debris-like mixtures each. The viscosity of these mixtures is tested in a viscometer. Then the solid grain fraction is added to the mixtures. For the experiment, each mixture is filled in a cylindric pipe, equipped with pressure sensors. During the experiments the temporal variation of fluid pressure is measured. The results support most of the assumptions made previously and also the prediction of the one-dimensional consolidation theory. The pressure development is mainly influenced by the viscosity of the mixtures, which is determined by the percentage of clay particles. For comparison and verification of the pressure variation, the diffusion coefficient defined by MAJOR (2000) is used. Variation of grain size distribution and percentage of solid grain fraction would be interesting for further research.