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An experimental and numerical study of alkali-activated fly ash paste

from dissolution kinetics to microstructure formation

Journal Article (2025)
Author(s)

Y. Chen (TU Delft - Materials and Environment, South China University of Technology)

Jiayi Chen (TU Delft - Materials and Environment)

Mayank Gupta (TU Delft - Materials and Environment)

Xuhui Liang (TU Delft - Materials and Environment)

Luiz Miranda de Lima

Zhiyuan Xu (TU Delft - Materials and Environment)

Y. Zuo (Huazhong University of Science and Technology)

Suhong Yin (South China University of Technology)

Qijun Yu (South China University of Technology)

G. (Guang) Ye (TU Delft - Materials and Environment)

Research Group
Materials and Environment
DOI related publication
https://doi.org/10.1016/j.cemconres.2025.107999
More Info
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Publication Year
2025
Language
English
Research Group
Materials and Environment
Volume number
198
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Abstract

This study presents an extended numerical approach based on GeoMicro3D to simulate the reaction kinetics and three-dimensional (3D) microstructure evolution of alkali-activated fly ash (AAFA). Dissolution experiments were conducted under varying NaOH concentrations and temperatures to formulate predictive rate functions for Si and Al release. These experimentally derived kinetic functions, alongside a thermodynamic dataset for N-(C-)A-S-H gels, were incorporated into the GeoMicro3D model to capture the chemical reactions and 3D microstructure evolution of AAFA. The model well captured reaction degree of fly ash, formation of solid products, evolution of pore solution compositions, and porosity over time. Notably, it is the first to predict the time-dependent spatial distribution of phases within the 3D AAFA microstructure by integrating kinetic and microstructural modeling. Dual validation using both dissolution data and microstructural metrics demonstrates the model's reliability and robustness. This integrated framework provides new insights into the coupled chemical–microstructural evolution of alkali-activated materials.