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Magnesium-based cements offer a sustainable alternative to traditional Portland cement, particularly due to their lower carbon footprint. Despite this advantage, these cements often exhibit lower mechanical properties, including reduced compressive strength. A promising approach to address these limitations is the incorporation of hydrated magnesium carbonates (HMC), such as hydromagnesite (Mg₅(CO₃)₄(OH)₂·4H₂O) and nesquehonite (MgCO₃·3H₂O) that densify the cement matrix and contribute to early-age strength. This study investigates the evolution of water-filled porosity in MgO-based cements with the addition of nesquehonite (Nq) or hydromagnesite (HY). Proton nuclear magnetic resonance (1H NMR) relaxometry measurements were carried out on sealed samples over the initial 28 days of hydration. The 1H NMR methods allowed to resolve the evolution of different water populations in the hydrating pastes: water in crystalline phases, intra-hydrate water (interlayer water), inter-hydrate water (water in between the hydrates) and free water in large capillaries. Although these populations are similar to those of Portland cements, their evolution kinetics and amplitudes are distinct. These results shed new light on the microstructure and hydration kinetics of the new MgO-based cements.

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Evolution of Porosity of MgO-Based Cements Studied with 1H NMR

  • 会议论文

  • 发表日期：

    2026年

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  • Siham Mouhtadi,
  • Vincent Hallet,
  • Barbara Lothenbach,
  • Frank Winnefeld,
  • Mateusz Wyrzykowski

摘要

Magnesium-based cements offer a sustainable alternative to traditional Portland cement, particularly due to their lower carbon footprint. Despite this advantage, these cements often exhibit lower mechanical properties, including reduced compressive strength. A promising approach to address these limitations is the incorporation of hydrated magnesium carbonates (HMC), such as hydromagnesite (Mg₅(CO₃)₄(OH)₂·4H₂O) and nesquehonite (MgCO₃·3H₂O) that densify the cement matrix and contribute to early-age strength. This study investigates the evolution of water-filled porosity in MgO-based cements with the addition of nesquehonite (Nq) or hydromagnesite (HY). Proton nuclear magnetic resonance (1H NMR) relaxometry measurements were carried out on sealed samples over the initial 28 days of hydration. The 1H NMR methods allowed to resolve the evolution of different water populations in the hydrating pastes: water in crystalline phases, intra-hydrate water (interlayer water), inter-hydrate water (water in between the hydrates) and free water in large capillaries. Although these populations are similar to those of Portland cements, their evolution kinetics and amplitudes are distinct. These results shed new light on the microstructure and hydration kinetics of the new MgO-based cements.