Rheological Characterization of Superplasticized Cement Pastes Containing Mineral Admixtures: Consequences on Self-Compacting Concrete Design

Abstract

The aim of this paper is to characterize different organic and mineral admixtures in order to evaluate their rheological behavior in cement pastes and their potential for incorporation into self compacting concrete (SCC). The admixtures tests are five commercial superplasticizers of various generations, acting by electrostatic, steric hindrance of combined effects; and four mineral admixtures (silica fume, metakaolin, fly ash and limestone filler) commonly used as cementitious materials and selected to achieve a large range of particle size, shape and chemical compositions. Rheological tests, using a modified Couette rheometer were performed on cement pastes to characterize the flow behavior of the admixtures and their rheological properties (yield stress and apparent viscosity). The results allow to propose some justifications concerning the suitability of these materials for their use in self compacting concrete. One example is the case of silica fume, which confers specific rheological characteristics to cement pastes that could be incompatible with the properties expected for SCC.