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Effect of Harsh Environments on the Mechanical Properties and Durability of Fly Ash-Based Geopolymer Concretes

Shokouhy, Amir Hossein | 2019

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52439 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Ghaemian, Mohsen; Toufigh, Vahab
  7. Abstract:
  8. In the present study, the performance of fly ash-based geopolymer concrete blended with cement as an additional calcium source under exposure to marine, acidic and alkaline environments was evaluated. Three mixtures of fly ash-based geopolymer concrete with different cement ratios (0, 10 & 20%) were prepared and immersed in tap water, seawater, sulfuric acid, and sodium hydroxide solutions for up to one year. Change in the appearance, weight, compressive strength, splitting tensile strength, energy absorption and microstructure of the specimens were evaluated at 1, 3, 6, 9 and 12 months of exposure. Ultrasonic pulse velocity test was also used to determine its relationship with the compressive strength of geopolymer concretes exposed to harsh environments. No significant visual signs of deterioration were observed in specimens under exposure to chemical solutions, and the maximum mass reductions in all specimens were below 1%. Results also showed that cement inclusion improved the mechanical properties of the control specimens (immersed in tap water), and the SEM analyses confirmed that the matrix becomes more compacted by adding slight amounts of cement as additional calcium in the geopolymer mixture. Comparison of the performances of mixtures with 10 & 20% cement also showed that in general, fly ash based geopolymer concrete with 20% cement as additional calcium performed better in terms of compressive strength, tensile strength, and energy absorption under exposure to chemical solutions. Exponential relationships were introduced for estimating the compressive strength from ultrasonic pulse velocity exposed to tap water and aggressive environments
  9. Keywords:
  10. Environment ; Fly Ash ; Durability ; Aquatic Media ; Concrete ; Acid Resistant ; Ultrasonic Pulse Velocity

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