Rheology, agglomerate structure, and particle shape of fresh geopolymer pastes with different NaOH activators content

This paper investigates the effect of NaOH activator content on the rheological properties of the fresh geopolymer pastes. Measurements on fluid, rheological properties (yield stress and plastic viscosity), microstructure (particle size distribution), geometrical property (HS Circularity and Elongation), and zeta potential of geopolymer fresh pastes were accomplished. Microstructure and geometrical property of geopolymer suspensions were observed by Morphologi G3 microscope. Results show that different NaOH activators content leads to notable changes on the microstructure and the rheological properties through significantly altering the charge characteristic of geopolymer surface. High NaOH activators content has low HS Circularity, high Elongation and zeta potential on the geopolymer suspensions. And as the main force between the particles, electrostatic repulsion plays an important role in the aggregation state of the particles in the early age. Higher zeta potential influences superior dispersion state of solid grains and stronger rheological properties of the geopolymer fresh pastes.