A novel adsorption–complexation–rheology model for PCE effects in early‐age Portland cement hydration

Abstract Superplasticizers play dual regulatory roles during early Portland cement hydration they retard hydration kinetics while enhancing paste fluidity. However, research gaps remain in quantitatively modeling the retardation behavior of superplasticizers and in establishing mechanistic linkages between the time‐dependent rheological effects in cementitious systems and the corresponding hydration processes under superplasticizer incorporation. In this study, a theoretical model was developed to predict the performance of polycarboxylate superplasticizers (PCEs) in Portland cement hydration. On the basis of obstruction theory and complexation reaction kinetics, the effects of adsorption and complexation were simulated to examine the retarding performance of cement hydration with PCE addition. Using rheological principles, mechanistic linkages between rheological evolution and hydration progression were established. Calorimetry and rheological experiments were conducted on Portland cement systems with varying PCE dosages. The experimentally measured hydration heat flow and yield stress data showed excellent agreement with the model predictions: the error in predicting the time to peak hydration heat release was within 10.46%; the overall error of the hydration heat release curve was within 17.31%; and the overall error of the yield stress curve was within 6.13%. This model not only provides theoretical guidance for admixture formulation based on engineering application requirements but also establishes a fundamental theoretical basis for future research on admixtures.