Early Hydration Kinetics and Microstructure Development of MgO-Activated Slag at Room Temperature
Publication: Journal of Materials in Civil Engineering
Volume 35, Issue 1
Abstract
In this paper, active MgO was used as the alkali activator, and the early hydration kinetics and microstructure development of MgO-activated slag were explored by means of the hydration heat test, X-ray diffraction (XRD), thermogravimetry (TG-DTG), Fourier transform infrared spectroscopy (FT-IR), mercury intrusion porosimetry (MIP), and scanning electron microscopy–energy dispersive spectrometry (SEM-EDS). Three types of MgO were selected based on reaction time (). The other two variables in this study include MgO content and curing age. The research results show that S-MgO is more suitable as an alkali activator and the total hydration heat of S-MgO-activated slag is much lower. The second exothermic peak is more obvious with the increase of MgO content. The main early hydration products of S-MgO-activated slag were a hydrotalcite-like phase, C-S-H gels, and C-A-S-H gels; the early main hydration product of R-MgO-activated slag was brucite. With the increase of MgO content, the total porosity decreases, i.e., the total porosity of the S-MgO specimen is the smallest, followed by the M-MgO specimen, and the total porosity of the R-MgO specimen is the largest. With the increase of S-MgO content, the processes of crystal nucleation and crystal growth are accelerated. When the S-MgO content is 20% by weight, the phase boundary reaction process and diffusion process of the MgO-activated slag system accelerates, which is more conducive to the diffusion, recombination, and precipitation of hydration products. This study provides an experimental and theoretical basis for the use of green alkali activator.
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Data Availability Statement
All data, models, and code generated or used during the study appear in the published article.
Acknowledgments
This research was funded by the High-level Innovative Talents Program of Hebei University (521100221036) and Science and Technology Project of Hebei Education Department (QN2022067) . The corresponding author acknowledges the financial support provided by the National Natural Science Foundation of China (51978025).
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Received: Jan 5, 2022
Accepted: May 4, 2022
Published online: Oct 26, 2022
Published in print: Jan 1, 2023
Discussion open until: Mar 26, 2023
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