Rheological properties of cementitious pastes with different types and contents of mineral additions

Reference Presenter Authors
(Institution)
Abstract
04-042 José Augusto Ferreira Sales de Mesquita Mesquita, J.A.(University of São Paulo); Maciel, M.H.(University of São Paulo); Romano, R.C.(University of São Paulo); Pileggi, R.G.(University of São Paulo); Brasileiro, G.C.(University of São Paulo); The partial substitution of Portland cement by mineral additions has been common practice in the construction sector in the present days, because this strategy brings to reduce the environmental impact of binder production chain. However, such association results in considerable changes in the fresh state properties, which may influence the hardened properties of products in use. So, the correct evaluation of fresh properties can to help to develop some compositions with better hardened properties. The viscosity is an important parameter related to energy dissipation of the suspension and indicates the resistance of the fluid during the flow. The intensity of this rheological parameter depends on thephysical interaction between the particles, whose can to be described by the Interference model. That model is related to particles size distribution, liquid viscosity and the distance between particles calculated by IPS (Interparticle Separation Distance), but do not consider the type of mineral additions. The main purpose of this work was to evaluate the rheological properties of cement pastes with different types and levels of mineral addition and comparing the viscosity results with the values obtained by the Interference model. Silica fume, metakaolin, ground blast furnace slag, limestone filler and red mud were used to replace 5 or 10% of Portland cement. The pastes were mixed using the same water-to-solid ratio and the fresh state was evaluated using rotational rheometry. The results indicated that both, type and content of addition, influenced the viscosity. Correlating these results with Interference it was not observed a clear tendency, but analyzing in function of each mineral addition it was obtained a good correlation, indicating that chemical changes also govern the viscosity of suspensions.
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