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<p>As the need for infrastructure development increases with a growing population, the dependence on cement consumption is rising, leading to a large amount of carbon dioxide (CO<sub>2</sub>) emissions into the atmosphere. This study investigates the mechanical performance, durability behaviour, and environmental benefits of ambient-cured geopolymer concrete (GPC) based on fly ash for infrastructure exposed to aggressive marine environments. A dual-source fly ash binder was activated using sodium hydroxide (NaOH) and sodium silicate (Na<sub>2</sub>SiO<sub>3</sub>) solutions, and specimens were exposed to coupled chloride-sulphate environments for up to one year. A 50:50 blend of processed and unprocessed non-calcareous fly ash, activated with 10&#xa0;M NaOH and Na<sub>2</sub>SiO<sub>3</sub> with modulus ratio of 2 achieved 37.4&#xa0;MPa compressive strength at 28&#xa0;days under ambient curing. Under coupled sulphate-chloride attack, the compressive strength initially decreased due to rapid ionic ingress, and partial depolymerization of the aluminosilicate gel. A transient strength recovery at 3-6&#xa0;months was attributed to continued geopolymerization and secondary gel formation that refined pore structure. Long-term degradation after 9-12&#xa0;months resulted from ion exchange (Na<sup>+</sup> replacement), increased pore connectivity, and microstructural relaxation. Chloride ion penetration test result (1879 C) and sorptivity analysis confirmed low ionic permeability, which was validated with mineralogical studies (SEM-EDAX and XRD analyses), confirming the formation of secondary gel formation and the absence of gypsum or ettringite phases before exposure. The developed GPC achieved 70.6% CO<sub>2</sub> reduction compared to OPC concrete, demonstrating durability-environment synergy for marine infrastructure applications.</p>

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Durability and mechanical behaviour of dual-sourced fly ash geopolymer concrete under aggressive environment

  • 期刊论文

  • 发表日期：

    2026年3月30日

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  • Sonal Thakkar,
  • Urmil Dave,
  • Shivanjali Rawat,
  • Abhishek Chanda,
  • Bhoomi Andharia

摘要

As the need for infrastructure development increases with a growing population, the dependence on cement consumption is rising, leading to a large amount of carbon dioxide (CO2) emissions into the atmosphere. This study investigates the mechanical performance, durability behaviour, and environmental benefits of ambient-cured geopolymer concrete (GPC) based on fly ash for infrastructure exposed to aggressive marine environments. A dual-source fly ash binder was activated using sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) solutions, and specimens were exposed to coupled chloride-sulphate environments for up to one year. A 50:50 blend of processed and unprocessed non-calcareous fly ash, activated with 10 M NaOH and Na2SiO3 with modulus ratio of 2 achieved 37.4 MPa compressive strength at 28 days under ambient curing. Under coupled sulphate-chloride attack, the compressive strength initially decreased due to rapid ionic ingress, and partial depolymerization of the aluminosilicate gel. A transient strength recovery at 3-6 months was attributed to continued geopolymerization and secondary gel formation that refined pore structure. Long-term degradation after 9-12 months resulted from ion exchange (Na+ replacement), increased pore connectivity, and microstructural relaxation. Chloride ion penetration test result (1879 C) and sorptivity analysis confirmed low ionic permeability, which was validated with mineralogical studies (SEM-EDAX and XRD analyses), confirming the formation of secondary gel formation and the absence of gypsum or ettringite phases before exposure. The developed GPC achieved 70.6% CO2 reduction compared to OPC concrete, demonstrating durability-environment synergy for marine infrastructure applications.