Predicting optimal dispersant (superplasticiser) content for cement–limestone pastes from rheological tests

Abstract

Currently, one of the most important trends in concrete technology is the use of inert fine particles (fillers) to decrease cement content, increase packing in the paste and increase flowability, with gains in technological, environmental and cost aspects. The advance in dispersion technology (using superplasticisers) is one of the technical issues that allows pastes to be mixed without the expected increase of water content – which decreases compressive strength – caused by the filler's high surface area. However, the use of no more than the optimal dispersant (superplasticiser) content (lowest content that provides the lowest viscosity) is crucial owing to cost constraints. This paper evaluates the possibility of predicting optimal dispersant content in cement–limestone filler systems from the optimal dispersant content previously measured in the pure raw materials. Owing to the need for only a few sets of tests, this can optimise the design timing and accuracy of efficient pastes for lower binder concretes.