Abstract
<title>Abstract</title> <p>Structure formation in reactive particulate suspensions is governed by the coupled evolution of particle connectivity, interfacial growth, and multiscale morphology. This study applies a modeling framework that integrates boundary nucleation and growth (BNG) kinetics with a fractal-based hydrate-bridging model for tricalcium silicate (C₃S) pastes. The framework describes the evolution of structural build-up measured by slow penetration tests and small-amplitude oscillatory shear (SAOS) across different water-to-solid ratios and calcium nitrate dosages. A fitted fractal-related parameter, β, is used as a model-derived descriptor of hydrate morphology and internal connectivity. The trends in β are corroborated by observations from scanning electron microscopy (SEM), dynamic light scattering (DLS), and ¹H nuclear magnetic resonance (NMR). In calcium nitrate-modified systems, the reduced hydrate size is consistent with classical dissolution-precipitation theory. At comparable hydration levels, β shows a positive correlation with T₂ relaxation time differences, suggesting that hydrate morphology influences pore filling. The temporal evolution of β, showing initial simplification followed by re-complexification, is consistent with Monte Carlo simulations. These results provide a physically informed interpretation of the link between hydrate-scale structural evolution and early-age rheological behavior within the proposed modeling framework.</p>