Effects of sulphates on the rheological behavior and electrokinetical properties of cement pastes for Self Compacting Concrete.

摘要

The use of admixtures, which tends to be generalized in the formulation of 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). In order to contribute on the understanding of these phenomena due to the presence of SO3 in cement, we propose to evaluate the action of certain sulphates, incorporating different types of sulfated additions (K2SO4, Na2SO4, and CaSO4.2H2O) to the cement paste. To this end, our work will concern the study of rheological properties and physical characteristics of the pastes obtained using two types of cement, namely, CPA and CRS. The experiment will focus on two reports: W/C = 0.30 for which the polynaphthalene sulphonate (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 that are functions of the nature of sulfates and cements used.