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<p>This study investigated the carbonation reactivity, carbonation products, and carbonation hardening properties of three low-calcium minerals—larnite (β-C<sub>2</sub>S), brownmillerite (C<sub>4</sub>AF), and mayenite (C<sub>12</sub>A<sub>7</sub>). The results showed that C<sub>12</sub>A<sub>7</sub> exhibited the highest carbonation reactivity. However, the carbonation hardening of β-C<sub>2</sub>S (78.2&#xa0;MPa) was significantly higher than C<sub>4</sub>AF (25.6&#xa0;MPa) and C<sub>12</sub>A<sub>7</sub> (21.2&#xa0;MPa). XRD and SEM analyses revealed that the carbonation of β-C<sub>2</sub>S produced calcium carbonate and a highly polymerized silica gel that formed a dense microstructure. In contrast, C<sub>4</sub>AF and C<sub>12</sub>A<sub>7</sub> generated more porous products with aluminum and iron gels having inferior bonding. It is thus evident that the silica gel in carbonated β-C<sub>2</sub>S induces superior hardening compared to the gels from calcium aluminates. This study demonstrates that silica gel formation imparts exceptional carbonation hardening properties to β-C<sub>2</sub>S despite its lower carbonation reactivity. The results provide insights into designing the mineral compositions of low-calcium cement for effective CO<sub>2</sub> sequestration.</p>

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Silica gel induced superior carbonation hardening in dicalcium silicate compared to calcium aluminates(ferrite)

  • 期刊论文

  • 发表日期：

    2025年6月29日

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  • Donglin Li,
  • Songhui Liu,
  • Saisai Zhang,
  • Hui Guo,
  • Xuemao Guan,
  • Jianping Zhu,
  • Caijun Shi

摘要

This study investigated the carbonation reactivity, carbonation products, and carbonation hardening properties of three low-calcium minerals—larnite (β-C2S), brownmillerite (C4AF), and mayenite (C12A7). The results showed that C12A7 exhibited the highest carbonation reactivity. However, the carbonation hardening of β-C2S (78.2 MPa) was significantly higher than C4AF (25.6 MPa) and C12A7 (21.2 MPa). XRD and SEM analyses revealed that the carbonation of β-C2S produced calcium carbonate and a highly polymerized silica gel that formed a dense microstructure. In contrast, C4AF and C12A7 generated more porous products with aluminum and iron gels having inferior bonding. It is thus evident that the silica gel in carbonated β-C2S induces superior hardening compared to the gels from calcium aluminates. This study demonstrates that silica gel formation imparts exceptional carbonation hardening properties to β-C2S despite its lower carbonation reactivity. The results provide insights into designing the mineral compositions of low-calcium cement for effective CO2 sequestration.