Influence of particle lattice effect on stability of suspensions: application to self-consolidating concrete

One of the parameters influencing the stability of a granular skeleton in a fluid is particle-size distribution ( PSD). This phenomenon partially originates from the particle lattice effect ( PLE) where in a given fluid the sedimentation behavior of one particle or a group of particles is modified in the presence of other particles. The PLE is of particular interest for the design of highly flowable concrete in which given the high fluidity of the paste, segregation of coarse aggregate is of concern. In the present study, the stability of several groups of bidisperse and polydisperse spherical glass particles ( 3-19 mm in diameter) suspended in limestone filler pastes designed with different rheological properties is investigated. Test results show that regardless of the PSD in the suspension, the PLE of any size-class is proportional to the volume fraction of such class. The main contribution of PLE to the enhancement of the stability of the overall system can be attributed to the stabilization of individual fine classes as the volume fractions of such classes are increased, instead of simply the interaction between different particle classes. Two indices are proposed to quantify the PLE potential of a given PSD and to predict the risk of segregation of a mixture of particles suspended in a yield stress fluid. The predictions made by the segregation index are shown to be feasible to apply to self-consolidating concrete ( SCC) mixtures.