Hy_Surf Model: Viscoelastic Evolution in Portland Cement Suspensions During the Early-Age Hardening

The hardening of cementitious suspensions at early stages of hydration is determined by the kinetics of the binder, which can be characterized by measuring the viscoelastic changes in the elastic storage modulus (G′) using oscillatory rheometry. This study aims to propose a new model that takes into account the physical-colloidal properties of suspensions and the transformations caused by hydration reactions, particularly the changes in the specific surface area of the particles. The model considers three mechanisms that influence viscoelastic evolution: agglomeration, bridging between particles after hydrate growth, and cohesion generated by attractive forces between C-S-H hydrates. The model, named Hy_Surf, was found to be highly correlated with experimental results, demonstrating its ability to accurately describe the mechanisms involved in the evolution of G′ during the first 4 h of hydration for various types of Portland cement, even when one of them had been prehydrated.