Rheology and microstructure of lithium slag/metakaolin geopolymer pastes: Insights from particle packing and water dynamic evolution

The high viscosity of alkali activator and physicochemical characteristics of metakaolin particles impair the rheological properties of fresh geopolymer pastes, becoming one of the urgent problems. To better understand and control the rheological properties of geopolymer pastes, this study investigates the particle packing of fluid suspensions and water dynamic evolution in pastes. The incorporation of lithium slag (LS) reduces the water required for the geopolymerization reaction, contributing to the increase of water film thickness between particles and the free water in pastes. Consequently, the internal friction between particles is reduced and the workability is improved. The results obtained identify the relevance of water film thickness and water occurrence state to qualitatively estimate the rheological properties, and confirm the applicability of LS for geopolymer manufacture. This work presents a theoretical approach towards assessing rheology and proposes an efficient method to develop more workable metakaolin-based geopolymer concrete.