Contribution of granular interactions to self compacting concrete stability: Development of a new device

Understanding the SCC behaviour is essential for resolving placement and consolidation problems in the field. As far as segregation is concerned, one of the main remaining obstacles is the design of a concrete mixture suitable for given casting conditions. Physical approaches which consist in studying the sedimentation of a single particle in a yield stress fluid failed to describe SCC static segregation. Segregation is a more complex phenomenon and the interactions between coarse aggregates have to be taken into account. They contribute to the stability of fresh SCC and this contribution should only depend on the solid fraction of the granular skeleton. A new experimental device has been developed in order to highlight and quantify the combined effects of coarse aggregates. This device allows studying lattices of particles. These latter are organised according to a cubic centred pattern and are immersed in a yield stress fluid. The experimental device and the test procedure are described in this paper. The validity of measurements has been demonstrated by performing a first series of tests and numerical simulations. Repeatability is quite satisfactory and “wall effects” can be limited.