Effect of limestone filler content and superplasticizer dosage on rheological parameters of highly flowable mortar under light pressure conditions

The influence of pressure on the yield stress and plastic viscosity of SCC mortars was investigated using an adapted Marsh cone with cylindrical shear paddles. Nine mortars proportioned with various limestone filler content and high-range water-reducing admixture (HRWRA) dosage from 0.65% to 0.85% were prepared. Test results show that when a pressure is exerted on the mortars, the material does not behave as a homogeneous fluid, i.e. having a yield stress depending only on the specific gravity of the mixture and the height of poured mortars and a constant value of plastic viscosity, but as a separative multiphasic material which consolidates, leading to exponential variations of τ0 and lowering values of μ with pressure. The HRWRA dosage or the limestone filler content has only an effect on the initial value of the yield stress, but has more influence on the variation of plastic viscosity of the mortar with pressure.