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<p>In the context of sustainable construction and industrial solid waste reduction, this study develops multi-component solid waste-based alkali-activated mortars (AAMs) to address the sulfate susceptibility and high carbon footprint of conventional cementitious materials. Using 100% industrial solid wastes, including ground granulated blast furnace slag (GGBFS), fly ash and steel slag, as precursors, AAMs were modified separately with 2.0% (mass fraction) nano-SiO<sub>2</sub> and 0.5% silicone-based hydrophobic agent (SHA) to evaluate their long-term performance under sulfate immersion. The key innovation lies in elucidating the distinct corrosion resistance mechanisms of the modified systems: nano-SiO<sub>2</sub> enhances gel formation through nucleation effects, while the SHA reduces fluid ingress by forming a barrier. Significant carbon reduction is also achieved compared with low-carbon materials (e.g., limestone-calcined clay cement (LC3)) through full solid waste utilization. Performance was evaluated via flexural strength, corrosion resistance coefficient, ion penetration, and microstructural characterization. The results show that increasing the GGBFS content from 30% to 70% improves both solid waste utilization and mechanical performance (8.12&#xa0;MPa at 112 d), whereas excessive fly ash reduces sulfate resistance. Both modifications enhance durability, with the nano-SiO<sub>2</sub>-modified system showing superior performance, limiting strength loss to 13.7% at 140 d (vs. 25.4% for the control) and effectively suppressing ion penetration. X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive X-ray (SEM–EDS) collectively suggest the formation of calcium-alumina-silicate-hydrate (C–A–S–H) gels, as evidenced by the broad amorphous features in the 2<i>θ</i> range of 10°–35°, the attenuation of aluminosilicate crystalline phases, the absence of detectable ettringite (AFt), and the formation of a dense gel-like matrix. The optimized AAMs enable high-value waste utilization and meet durability requirements in harsh environments, offering a sustainable material for low-carbon infrastructure. Furthermore, the use of 100% industrial solid waste eliminates clinker-related CO<sub>2</sub> emissions and provides significant environmental benefits.</p>

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Sulfate corrosion resistance of multi-component solid waste-based alkali-activated cementitious materials under full immersion conditions

  • 期刊论文

  • 发表日期：

    2026年7月1日

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  • Tengyou Jiang,
  • Jingjun Li,
  • Fuliang Zuo,
  • Xuelian Zhang,
  • Yongbo Huang

摘要

In the context of sustainable construction and industrial solid waste reduction, this study develops multi-component solid waste-based alkali-activated mortars (AAMs) to address the sulfate susceptibility and high carbon footprint of conventional cementitious materials. Using 100% industrial solid wastes, including ground granulated blast furnace slag (GGBFS), fly ash and steel slag, as precursors, AAMs were modified separately with 2.0% (mass fraction) nano-SiO2 and 0.5% silicone-based hydrophobic agent (SHA) to evaluate their long-term performance under sulfate immersion. The key innovation lies in elucidating the distinct corrosion resistance mechanisms of the modified systems: nano-SiO2 enhances gel formation through nucleation effects, while the SHA reduces fluid ingress by forming a barrier. Significant carbon reduction is also achieved compared with low-carbon materials (e.g., limestone-calcined clay cement (LC3)) through full solid waste utilization. Performance was evaluated via flexural strength, corrosion resistance coefficient, ion penetration, and microstructural characterization. The results show that increasing the GGBFS content from 30% to 70% improves both solid waste utilization and mechanical performance (8.12 MPa at 112 d), whereas excessive fly ash reduces sulfate resistance. Both modifications enhance durability, with the nano-SiO2-modified system showing superior performance, limiting strength loss to 13.7% at 140 d (vs. 25.4% for the control) and effectively suppressing ion penetration. X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive X-ray (SEM–EDS) collectively suggest the formation of calcium-alumina-silicate-hydrate (C–A–S–H) gels, as evidenced by the broad amorphous features in the 2θ range of 10°–35°, the attenuation of aluminosilicate crystalline phases, the absence of detectable ettringite (AFt), and the formation of a dense gel-like matrix. The optimized AAMs enable high-value waste utilization and meet durability requirements in harsh environments, offering a sustainable material for low-carbon infrastructure. Furthermore, the use of 100% industrial solid waste eliminates clinker-related CO2 emissions and provides significant environmental benefits.