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Carbonation and Phase Evolution in MgO-SiO2 Cements: Impact on Strength
Gonzalo Mármol1, Ana Fernández-Jiménez1, María-Teresa Blanco-Varela1
1Eduardo Torroja Institute for Construction Science (IETcc-CSIC), Serrano Galvache, 4, 28033 Madrid, Spain.
Molecules (Basel, Switzerland)
|March 13, 2025
Summary
Early carbonation of magnesium silicate hydrate (M-S-H) binders, using magnesia and silica, influences phase evolution and mechanical properties. This process affects strength development and mineralogy in MgO-SiO2 cementitious systems.
Area of Science:
- Materials Science
- Geochemistry
- Civil Engineering
Background:
- Magnesium silicate hydrate (M-S-H) binders offer potential but struggle with early strength due to slow MgO solubility and hydration kinetics.
- Understanding the influence of environmental factors like carbonation is crucial for optimizing MgO-SiO2 cementitious systems.
Purpose of the Study:
- To investigate the impact of early carbonation on MgO-SiO2 cementitious systems.
- To analyze the effects of CO2 exposure on phase evolution, M-S-H gel formation, and mechanical performance.
- To identify strategies for enhancing early strength development in these binders.
Main Methods:
- Exposure of MgO-SiO2 cementitious systems to CO2-saturated atmospheres at early stages.
- Characterization using X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS), and Fourier Transform Infrared Spectroscopy (FTIR).
- Evaluation of mechanical strength development and phase composition.
Main Results:
- Early carbonation promotes the formation of hydrated magnesium hydroxycarbonates (HMHC), altering hydration pathways.
- Increased carbonation levels correlate with reduced magnesium hydroxide (Mg(OH)2) stability and M-S-H gel content.
- Significant impacts on mineralogy and early-age mechanical strength were observed, influenced by formulation and water-to-cement ratio.
Conclusions:
- Early carbonation significantly influences phase evolution and mechanical properties in MgO-SiO2 cementitious systems.
- The formation of HMHC phases due to carbonation affects the stability of Mg(OH)2 and the overall M-S-H gel content.
- Optimizing formulation, water-to-cement ratio, and early carbonation exposure is key to developing efficient MgO-SiO2 cement systems with improved strength and reduced reliance on reactive silica.
Keywords:
CO2 encapsulationM-S-H cementcarbonationhydrated magnesium hydroxycarbonatespore refinementMore Related Videos
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