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The cement industry contributes 5–7% of global carbon dioxide (CO₂) emissions, significantly impacting climate change. Geopolymer concrete (GPC) technology offers a sustainable alternative, reducing CO₂ emissions while delivering excellent physical properties, including high early strength and low shrinkage. GPC, primarily derived from metakaolin, fly ash, kaolin, and slag, demonstrates remarkable mechanical performance and acid and alkali corrosion resistance. Basalt fiber-reinforced polymer (BFRP) rebars, an eco-friendly material with superior corrosion resistance compared to steel, enhance durability under harsh environmental conditions. This study investigated fifteen GPC mixes to evaluate the effects of aggregate type, water glass (WG)/cementitious material (CM) ratio, fly ash substitution for metakaolin, curing temperature, and fiber inclusion on compressive and flexural strength. Results showed that curing at 60 °F enhanced early-age compressive strength, whereas higher temperatures caused porosity and voids. A 20% fly ash replacement and using river gravel improved workability, yielding GPC with compressive and flexural strengths of 9400 psi and 800 psi, respectively. A low-shear mixer ensured homogeneity by blending metakaolin with water glass before adding aggregates. GPC crossties reinforced with #3 BFRP rebars were developed and tested, advancing durability in railroad infrastructure and demonstrating excellent ultimate strength capacity.

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Experimental Study on the Optimization of Metakaolin-Based Geopolymer Concrete (GPC) for Prestressed Railroad Concrete Crossties

  • 会议论文

  • 发表日期：

    2025年

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  • Mohsen A. Issa,
  • Ghassan Al-Chaar,
  • Mounir Kassem,
  • Mohammad Mahdi,
  • Alain Saroufim,
  • Ahmad El Refae

摘要

The cement industry contributes 5–7% of global carbon dioxide (CO₂) emissions, significantly impacting climate change. Geopolymer concrete (GPC) technology offers a sustainable alternative, reducing CO₂ emissions while delivering excellent physical properties, including high early strength and low shrinkage. GPC, primarily derived from metakaolin, fly ash, kaolin, and slag, demonstrates remarkable mechanical performance and acid and alkali corrosion resistance. Basalt fiber-reinforced polymer (BFRP) rebars, an eco-friendly material with superior corrosion resistance compared to steel, enhance durability under harsh environmental conditions. This study investigated fifteen GPC mixes to evaluate the effects of aggregate type, water glass (WG)/cementitious material (CM) ratio, fly ash substitution for metakaolin, curing temperature, and fiber inclusion on compressive and flexural strength. Results showed that curing at 60 °F enhanced early-age compressive strength, whereas higher temperatures caused porosity and voids. A 20% fly ash replacement and using river gravel improved workability, yielding GPC with compressive and flexural strengths of 9400 psi and 800 psi, respectively. A low-shear mixer ensured homogeneity by blending metakaolin with water glass before adding aggregates. GPC crossties reinforced with #3 BFRP rebars were developed and tested, advancing durability in railroad infrastructure and demonstrating excellent ultimate strength capacity.