Spreading of granular pastes: from the particle to end use properties

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Granular pastes as highly concentrated particle suspensions, such as gypsum pastes and fresh concretes, play an important role in the manufacturing of different products in the construction, chemical and food industries. These materials are non-Newtonian fluids whose complex rheological properties (yield stress, thixotropy) need to be understood and described with physical based models to optimize the end-use properties of these products in connection with their formulation. One possibility to optimize the flow behavior of the pastes is to apply mechanical vibration for targeted control of their viscosity. In this cooperation project, we will combine the experimental and numerical tools to investigate the flow behavior of granular pastes under influence of vibration. On the microscale the characteristic parameters of the micro processes and the interactions between phases (particle-particle, particle-fluid, particle-wall and fluid-wall) will be obtained. The particles will be simulated with the help of the Discrete Element Method (DEM). To consider the micro interactions between the liquid and particles the DEM will be coupled with a CFD approach. These models will be developed at the Institute of Particle Process Engineering (University of Kaiserslautern, Germany). They will be validated with the rheological experiments performed at LEMTA laboratory (University of Lorraine, Nancy, France). Based on the experimental and numerical results we will be able to identify the mechanisms of the shear flow, particle transport and energy dissipation to provide the parameters that can be used in physical models on the macroscale. With the help of a developed multiscale model, it will be possible to obtain detailed information about the influence of the microprocesses on the macroscopic flow behavior of the granular pastes during vibration. This can be used for the optimization of the spreading properties of granular paste with controlled formulation.