Microrheological modeling of time-dependent rheology in gypsum-based materials: Bridging chemical admixture effects and hydration dynamics

This study presents a comprehensive investigation into the influence of chemical admixtures (polycarboxylate, citric acid, starch ether, and hydroxypropyl methyl cellulose) on the rheological properties and hydration kinetics of gypsum-based material (GM) pastes. Through integrated steady-state rheometry, dynamic oscillatory analysis, and calorimetric hydration monitoring, we systematically characterize the time-dependent rheological evolution and its correlation with hydration processes. A microrheological framework based on active suspension theory is employed to quantitatively evaluate admixture effects through two key parameters: flocculation rate and relative hydration degree. The developed model successfully establishes coupled relationships between admixture chemistry, hydration dynamics, and macroscopic rheological behavior, demonstrating superior predictive accuracy. This microrheological approach not only enables precise workability control in GM systems but also provides a transferable paradigm for rheological analysis of inorganic cementitious materials.