The influence of alkalis on rheological properties of fresh cement pastes

Abstract

The following paper presents the results of the research carried out to investigate the influence of alkalis built in clinker phases and introduced from the outside together with make-up water, on the rheological properties of pastes in Portland cement at an early stage of hydration (less than 1 hour). The estimation of the alkaline influence of rheological properties of fresh clinker and cement pastes was performed referring to the obtained consistency curves and stress change characteristics in time and at constant shear rate. It was found that clinker reactivity exerts an influence on the consistency of the cement paste prepared using this very same clinker. The effect of gypsum as a controller of setting depends on the clinker reactivity. The more reactive the clinker is, the smaller is the influence of alkalis introduced into make-up water, on consistency and consistency changes in the time of cement pastes.