This work has been initiated to improve the development of mineral suspension used for building construction. In this industrial field, the rheological evolution needs to be controlled from the mixing to the setting up. The study is herein focused on the influence of polycarboxylates superplasticizers as additives on the rheological properties of suspensions made with a reactive anhydrite. Firstly, we develop some protocols of rheological characterization which have been calibrated using a model yield stress fluid. Then, we evaluated the effect of several experimental parameters: the sample gap, the roughness of the plates, pre-shearing as well as the testing time. We finally used a unique protocol to identify the flow curves of the mineral suspensions. In addition, dynamic rheometry was used to study the viscoelastic properties of the suspensions at low strain with two rheometers equipped with different geometries. We assessed the physico-chemical characterization of thevarious additives selected for this study In order to provide the knowledge on their molecular shape. We distinguished several parameters such as: molecular weight and the thermorheologicalbehavior in alkaline or neutral conditions. Moreover, we performed adsorption measurements on tow additives. We showed that the adsorption phenomenon is mainly governed by a weak amount of calcium hydroxide within the suspensions. We observed significant differences on the rheological responses according to the solid volume fraction and the superplasticizers used into the mineral suspension. We identified the evolution of the consistency and the yield stress, derivedwith the Herschel-Bulkley model, against the solid volume fraction and the quantity of the additive. Then, we adjust a Krieger-Dougherty type model on the results. It was shown that the power parameter of this model may be linked to the roughness of the particles covered by the adsorbed layer of superplasticizers. The parameters affecting the rheology were the molecular weight and the polymolecularity index of the polycarboxylates. Nevertheless, these results are more obvious with the evolution of the consistency than the yield stress. As the relation between consistency and yield stress was highlighted, it could be possible to only measure the yield stress of the suspensions. This is here performed from the release of finite volume of material onto a horizontal surface. We experimentally observed that following its yield stress, the material may show a typical shape at the flow stoppage, between slump and spread. Based on these observations, we propose a new analytical model to evaluate the yield stress of the suspensions. Results showed the relevance of the proposed model, in comparison to previous models. The model developed here may be used for different sample sizes and for a wide range of yield stress fluids. The relationship between viscosity and yield stress of the mineral suspensions is discussed by evaluating the viscosity from Marsh cone tests. We finally showed that a hand-made rheometry is relevant for an industrial application. In order to improve the understanding of the adsorbed layer around the particles, a phenomenological approach at a microscopic scale is proposed. From oscillatory measurements, the interparticle distance within the suspensions is evaluated and ranges from 1 to 5 nm. This henomenological approach allowed us to highlight the influence or the solid volume fraction on the interparticle distance. Finally, we investigated from rheological measurements the liquid-solid transition of the suspensions caused by the hydratation reactions. Static and dynamic measurements were also performed to follow the structural evolution at rest of the suspensions versus time. A characteristic evolution of the normal force during the setting time of the suspensions is shown.
