Effect of mineral admixtures on the rheological and mechanical properties of mortars

摘要

We propose in this study to determine the role of mineral admixtures on the properties of cementitious materials in order to define a formulation method allowing an optimization of their use and the improvement of the rheological and mechanical properties of the mortars. In order to meet the objectives of this study, and to evaluate the effects that mineral admixtures may have on the properties of mortars in the fresh and hardened state, we have proposed to use a specific method based on progressive volume substitution of cement by the mineral admixtures, in order to preserve the absolute volume of all the solid constituents and the consistency for all the mixtures. The use of the mineral admixtures in the mortars also has for objective to valorize a category of natural materials or coproducts available in Algeria. As a result, the mineral admixtures chosen for this study are Blast furnace Slag, natural pozzolan and silica fume. Then the effect of the mineral admixtures on the rheological and mechanical properties of the mortars was evaluated according to the substitution rate of the cement. We applied to the studied mortars the notion of equivalent binder in order to calculate the coefficient of activity (K) defined by the two theoretical formulas Féret and Bolomey. The specific chemical action of each mixture was evaluated by analysing the variation of the coefficient of activity K as a function of the rate of substitution of the cement.