A novel lattice-based framework for the hydration and microstructural evolutions of CaO-activated ground granulated blast-furnace slag

Abstract

Use of CaO-activated ground granulated blast-furnace slag (CA-BFS) as an alternative to Portland cement has recently attracted significant attention; however, determining its properties still requires extensive experimental work and high costs. Therefore, a novel framework, alkali-activated materials hydration 3 dimensions (AAMHyd3D), was developed to predict the hydration and microstructural evolution of CA-BFS using a lattice-based approach. Chemical reactions were derived from the literature, while the BFS hydration rate was determined using transition state theory. The model explicitly simulated CaO dissolution, nucleation and growth of hydration products, and diffusion-hydration reactions between calcium hydroxide (CH) and BFS. AAMHyd3D was validated through X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and isothermal calorimetry (IC). A 6 wt% CaO substitution provided optimal performance, whereas 8 wt% reduced compressive strength. The simulated results showed good agreement with experiments in terms of microstructural development, heat evolution, degree of hydration, and phase evolution, with integral absolute errors ranging from 0.7% to 8.3%. In addition, the sensitivity analysis of key parameters including reference hydration rate (rref), solubility products (Ksp), and conversion factor (beta) were explored. The results showed that the rref significantly affected the hydration process compared with the Ksp and beta. This study supports the development of sustainable low-carbon binders as alternatives to Portland cement for reducing CO2 emissions.