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<p>The use of direct and treated recycled concrete aggregate (RCA) mitigates natural aggregate depletion, reduces construction and demolition (C&amp;D) waste, and promotes sustainable construction. However, the fire resistance of treated recycled aggregate concrete (RAC) remains a critical concern. This study investigates the physical, mechanical, and microstructural performance of banana fiber-reinforced diatomaceous earth (DE) slurry-treated RAC at room temperature and after exposure to 200&#xa0;°C, 400&#xa0;°C, 600&#xa0;°C, and 800&#xa0;°C. Three treated coarse RCA types were produced by coating RCA with a slurry containing 5% DE, treated banana fiber (3%, 5%, and 7%), and ordinary Portland cement. The heating methodology followed the ISO 834 standard fire curve, and results were compared to those of concrete made with untreated RCA (UT-RAC) and natural aggregate (NAC). Concrete incorporating optimally treated RCA (5/5-RAC) retained 26–30% more compressive strength than UT-RAC and over 95% of NAC’s strength across all temperature exposures. The density improved by 15–20%, while peak strain decreased by 8.2–18.0%, indicating enhanced stiffness. The splitting tensile strength increased by 18–22%, while mass loss, capillary water absorption, and porosity were reduced by 20%, 25%, and 27.42%, respectively, at 800&#xa0;°C. X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) confirmed improved retention of calcium silicate hydrate (C-S–H) phases and reduced microstructural degradation in treated RAC. The combined action of DE and banana fibers enhanced ITZ densification, C-S–H phase stability, and thermal crack resistance. These findings demonstrate that optimized DE-banana fiber slurry treatment can significantly improve the fire resistance and structural performance of RAC, contributing to sustainable construction.</p>

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Banana fiber-reinforced diatomaceous earth slurry treatment for enhancing structural recycled aggregate concrete under elevated temperatures

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年12月23日

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  • Habtamu Melesse Dicha,
  • Momin Noman Husain,
  • Sandeep Chaudhary,
  • Ramaswamy Krishnaraj

摘要

The use of direct and treated recycled concrete aggregate (RCA) mitigates natural aggregate depletion, reduces construction and demolition (C&D) waste, and promotes sustainable construction. However, the fire resistance of treated recycled aggregate concrete (RAC) remains a critical concern. This study investigates the physical, mechanical, and microstructural performance of banana fiber-reinforced diatomaceous earth (DE) slurry-treated RAC at room temperature and after exposure to 200 °C, 400 °C, 600 °C, and 800 °C. Three treated coarse RCA types were produced by coating RCA with a slurry containing 5% DE, treated banana fiber (3%, 5%, and 7%), and ordinary Portland cement. The heating methodology followed the ISO 834 standard fire curve, and results were compared to those of concrete made with untreated RCA (UT-RAC) and natural aggregate (NAC). Concrete incorporating optimally treated RCA (5/5-RAC) retained 26–30% more compressive strength than UT-RAC and over 95% of NAC’s strength across all temperature exposures. The density improved by 15–20%, while peak strain decreased by 8.2–18.0%, indicating enhanced stiffness. The splitting tensile strength increased by 18–22%, while mass loss, capillary water absorption, and porosity were reduced by 20%, 25%, and 27.42%, respectively, at 800 °C. X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) confirmed improved retention of calcium silicate hydrate (C-S–H) phases and reduced microstructural degradation in treated RAC. The combined action of DE and banana fibers enhanced ITZ densification, C-S–H phase stability, and thermal crack resistance. These findings demonstrate that optimized DE-banana fiber slurry treatment can significantly improve the fire resistance and structural performance of RAC, contributing to sustainable construction.