Fly Ash and Sinking Beads Modification on the Rheological Properties of Cement Paste with Metakaolin

The aim of this study was to investigate the respective effect of sinking beads (SBs) and fly ash (FA) on the rheological properties of metakaolin (MK)-blended pastes and to uncover the relevant mechanisms from the aspects of morphology and electrochemistry. The yield stress, plastic viscosity, and slump diameter of cement pastes were studied, as well as the zeta potential of the diluted cement pastes. The results show that SB can much more remarkably improve the rheology of MK-blended cement pastes than FA, and ensures 5 wt.% MK-blended cement paste a competitive flowability with plain paste. The synergistic effects of morphological and electrochemical modification on cement paste result in the different modification efficiency of FA and SB on blended pastes.