The use of admixtures which tends to be generalized in the formulation of self-compacting concrete (SCC), requires taking into account the chemical composition of cement, particularly its content of SO₃, which can inhibit or restrain the effect of these admixtures (superplasticizers). For more information of the compatibility problem of cement-superplasticizer, the rheological tests with a rheometer-AR2000 and measurements of zeta potential with a Zêtasiser-2000 were used in this study. In order to understand this phenomenon due to the presence of SO₃ in cement, we propose to evaluate the action of alkaline and alkaline-earth ions, incorporating different types of additions (K⁺, Na⁺, and Ca²⁺) to the cement pastes. To achieve this, our work will concern the study of rheological properties and physical characteristics of the pastes obtained using two types of cement (C1: Cement Resistant to the Sulfates (CRS) and C2: CEMI). This experiment will focus on two reports: Water/Cement (W/C) = 0.30 for which the polynaphthalene sulfonate (PNS) is used as superplasticizer and W/C = 0.50 (without superplasticizer). The results show that the presence of sulfate leads to different rheological behaviors which are function of sulfates and the cements used.

Key words: Cement, rheology, superplasticizer, yield stress, plastic viscosity, self-compacting concrete, sulfates.