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<p>This study investigates geopolymer mortar’s durability and mechanical performance with partial fly ash (FA) replacement by rice husk ash (RHA) and different alkaline concentrations. Forty-eight (48) mortar cubes were tested to assess compressive strength under different curing conditions and exposure to aggressive chemical environments. Two molar concentrations of sodium hydroxide (12&#xa0;M and 14&#xa0;M) were used as alkaline activators, along with sodium silicate, with FA replaced by RHA at varying levels (0%, 3%, 6%, 9%, 12%, and 15%). The results showed that increasing the RHA content improved the compressive strength, particularly at 28&#xa0;days of ambient curing. However, the early-stage strength development (1-day heat curing) decreased as the RHA percentage increased, with reductions in strength gain observed at higher RHA levels. After 9&#xa0;weeks of exposure to 5% sulfuric acid (H₂SO₄) and 5% sea salt (NaCl) concentration, durability tests showed that specimens with higher RHA content experienced more significant strength degradation. Notably, the NaCl resistance was more significant compared to H₂SO₄. In addition, increasing the molarity of NaOH from 12 to 14&#xa0;M enhanced the compressive strength of the specimens by 11% and the acid resistance by 7%. The results indicate that while RHA can improve the mechanical properties of geopolymer mortars, its effect on durability in acidic environments requires careful study. This study concludes that RHA is a viable alternative to FA in geopolymer mortars, providing improved long-term strength, but its effect on chemical durability deserves further investigation for practical applications.</p>

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Durability and mechanical performance of geopolymer mortar with partial replacement of fly ash by rice husk ash and variations in alkaline activator concentrations

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年4月28日

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  • Esamaddin M. Mulapeer,
  • Ali H. Omar

摘要

This study investigates geopolymer mortar’s durability and mechanical performance with partial fly ash (FA) replacement by rice husk ash (RHA) and different alkaline concentrations. Forty-eight (48) mortar cubes were tested to assess compressive strength under different curing conditions and exposure to aggressive chemical environments. Two molar concentrations of sodium hydroxide (12 M and 14 M) were used as alkaline activators, along with sodium silicate, with FA replaced by RHA at varying levels (0%, 3%, 6%, 9%, 12%, and 15%). The results showed that increasing the RHA content improved the compressive strength, particularly at 28 days of ambient curing. However, the early-stage strength development (1-day heat curing) decreased as the RHA percentage increased, with reductions in strength gain observed at higher RHA levels. After 9 weeks of exposure to 5% sulfuric acid (H₂SO₄) and 5% sea salt (NaCl) concentration, durability tests showed that specimens with higher RHA content experienced more significant strength degradation. Notably, the NaCl resistance was more significant compared to H₂SO₄. In addition, increasing the molarity of NaOH from 12 to 14 M enhanced the compressive strength of the specimens by 11% and the acid resistance by 7%. The results indicate that while RHA can improve the mechanical properties of geopolymer mortars, its effect on durability in acidic environments requires careful study. This study concludes that RHA is a viable alternative to FA in geopolymer mortars, providing improved long-term strength, but its effect on chemical durability deserves further investigation for practical applications.