Les comportements rheologiques du mortier frais

There are two critical values of the concentration C of the dispersed solid in fresh mortars called C_i and C_d such that, for angular granulates, when C ? C_i, the behaviour is binghamian at rest and pseudoplastic when the mortar is vibrated; when C ? C_d, it is dilatant in the two cases and when C_i < C < C_d, it is unstable. For spherical granulates, these behaviours are unchanged, except under vibration when C ? C_i : in this case, the behaviour is newtonian. These changes of behaviour are explained by structural modifications in the packing of particles : dilatancy comes out with close-packing while instability appears with maximum loose-packing.