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<p>Magnesia-based cements (MBCs) are promising low-carbon alternatives to conventional portland cement due to their lower calcination temperature requirements and ability to utilize magnesia derived from carbon-free feedstocks. Understanding these systems requires deep knowledge of the entire reaction sequence: from the initial dissolution of magnesia (MgO) particles and the transport of magnesium ions through solution, to the precipitation of brucite [Mg(OH)₂], and ultimately of binding phases such as magnesium silicate hydrates (M–S–H) or magnesium carbonates. While these reaction steps resemble those in CaO-based systems, fundamental differences in thermodynamic and kinetic behaviors result in key differences in the dissolution and precipitation pathways of MBCs. To further explicate these differences, this review utilizes thermodynamic simulations revealing the effect of chemical additives (complexing ligands) on the solubility of Mg(OH)<sub>2</sub>, as the main intermediate phase in the precipitation of MBC binding phases. The inherent low solubility of Mg(OH)₂ is a key limitation that, upon further understanding and tailoring with chemical additives, can tailor the molecular pathways of Mg dissolution and transport, leading to controlled growth—paramount for optimizing strength development and durability in MgO-based cementitious materials.</p>

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Dissolution, diffusion, and precipitation of Mg2+ in MgO-based cements, a review by the RILEM TC-311 MBC

  • 期刊论文

  • 发表日期：

    2026年3月23日

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  • Juan Pablo Gevaudan,
  • Cristina Ruiz-Agudo,
  • Hegoi Manzano,
  • Hoang Nguyen,
  • Barbara Lothenbach,
  • Paivo Kinnunen,
  • Ellina Bernard

摘要

Magnesia-based cements (MBCs) are promising low-carbon alternatives to conventional portland cement due to their lower calcination temperature requirements and ability to utilize magnesia derived from carbon-free feedstocks. Understanding these systems requires deep knowledge of the entire reaction sequence: from the initial dissolution of magnesia (MgO) particles and the transport of magnesium ions through solution, to the precipitation of brucite [Mg(OH)₂], and ultimately of binding phases such as magnesium silicate hydrates (M–S–H) or magnesium carbonates. While these reaction steps resemble those in CaO-based systems, fundamental differences in thermodynamic and kinetic behaviors result in key differences in the dissolution and precipitation pathways of MBCs. To further explicate these differences, this review utilizes thermodynamic simulations revealing the effect of chemical additives (complexing ligands) on the solubility of Mg(OH)2, as the main intermediate phase in the precipitation of MBC binding phases. The inherent low solubility of Mg(OH)₂ is a key limitation that, upon further understanding and tailoring with chemical additives, can tailor the molecular pathways of Mg dissolution and transport, leading to controlled growth—paramount for optimizing strength development and durability in MgO-based cementitious materials.