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Effects of Re-Curing on Mechanical Properties of Concrete Containing Rice Husk Ash after High Temperature Exposure

Nazari, Ali | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 57955 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Toufigh, Vahab
  7. Abstract:
  8. Research on the impact of high temperatures on the mechanical properties of concrete is crucial for fireproof design, safety assessments, and repairing fire-damaged structures. However, there is a lack of research on the effects of water re-curing on thermally damaged concrete. This study aims to explore how high temperatures and water re-curing affect the compressive behavior of concrete with varying percentages of rice husk ash (0, 4, 8, 10, and 12%). The compressive behavior was assessed by analyzing stress-strain responses and parameters such as compressive strength, modulus of elasticity, strain at peak stress, ultimate strain, absorbed energy, failure mode, and visual observations. Concrete samples were exposed to different temperatures (300, 500, and 700 degrees), followed by water re-curing processes to evaluate deterioration and recovery. The results indicate a significant decrease in mechanical properties with increasing temperature, with the most significant drop observed at 700 degrees, resulting in an average decrease of 42% in compressive strength and 79% in modulus of elasticity. The mechanical properties of both heated and unheated concrete samples were enhanced by the addition of rice husk ash (RHA), with the optimal replacement percentage being 8% of the weight of the cement. The compressive strength and modulus of elasticity of heated concrete saw a significant increase after water re-curing. A stress-strain model was developed to predict the compressive behavior of concrete containing RHA under high temperatures and post-heat water re-curing, showing good agreement with experimental results. The response surface method (RSM) was utilized to optimize design parameters and maximize compressive strength at various temperatures and after water re-curing
  9. Keywords:
  10. Response Surface Method ; Rice Husk Ash ; High Temperature ; Temperature Effect ; Microstructural Analysis ; Compressive Stress-Strain Behavior ;

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