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Exploring the aluminium paradox in calcium-aluminosilicate-hydrate decalcification.
Yong Tao1,2, Yining Gao3, Mohammad Javad Abdolhosseini Qomi4,5,6
1Department of Civil and Environmental Engineering, Research Centre for Resources Engineering towards Carbon Neutrality, The Hong Kong Polytechnic University, Hong Kong, China. yong.tao@polyu.edu.hk.
Nature Communications
|December 15, 2025
Summary
Aluminium
Area of Science:
- Materials Science
- Geochemistry
- Mineralogy
Background:
- Decalcification degrades cementitious materials and weathers Earth's silicates.
- The role of aluminium (Al) in calcium-silicate-hydrate (C-S-H) decalcification is debated.
Purpose of the Study:
- To elucidate the atomistic mechanisms of Al in calcium-aluminosilicate-hydrate (C-A-S-H) decalcification.
- To understand how Al incorporation affects C-A-S-H stability and degradation.
Main Methods:
- Metadynamics simulations
- Density functional theory calculations
- Experimental characterizations
Main Results:
- Aluminium exhibits a dual effect on decalcification based on its concentration.
- Aluminium incorporation can either accelerate or hinder decalcification by altering aluminosilicate chain structures.
- Preferential sodium (Na) ion dissolution suppresses calcium (Ca) ion dissolution.
- Calculated activation free energies accurately predict experimental decalcification kinetics.
Conclusions:
- Aluminium's impact on C-A-S-H decalcification is complex and depends on compositional ratios.
- This research provides a framework for controlling mineral degradation.
- Findings offer fundamental insights into geological and environmental processes.
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