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Durability Evaluation and Health Monitoring of Microcracked Slag-Based Geopolymer Concrete Due to Step by Step Pressure Loading

Keyvan, Kaveh | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56317 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Ghaemian, Mohsen; Toufigh, Vahab
  7. Abstract:
  8. The goal of this research is to study the effect of local microcracking due to step by step pressure loading on the durability properties of geopolymer concrete. To better understand the behavior of GGBS-based GPC under different pressure stress levels, some experiments such as water permeability and water absorption conducted on the samples at each state of damage. Also, non-destructive tests such as ultrasonic waveform and pulse velocity (UPV) was used to quantify the extent of damage at each step. GGBFS and a blend of sodium silicate solution and 10 molar sodium hydroxide solution with SSSH⁄ ratio of 2 were used for production of GPC samples. GPC, OGPC and OPC samples with water to binder ratio of 0.45 achieved compressive strengths of 64, 60 & 58 MPa after 28 days of curing, respectively. A total of 57 cubic samples (15×15×15 mm) were loaded under uniaxial compression at levels of 25, 50 and 75 percent of compressive strength. obtained results of different experiments were used to evaluate the deterioration of concretes at each state of local damage. To better understand the effect of crack recovery in the experiment results, pulse velocity test was also conducted on the samples in the presence of loading to compare the UPV results with those after unloading. The experimental outcomes demonstrate that the permeability decreases or remains constant with increasing the compressive loading up to a threshold stress and by exceeding it, an increase in the permeability occurs. the threshold stress of GPC, OGPC and OPC samples is, respectively, higher than 50%, around 50% and between 25% to 50% of their compressive strength. In general, it was concluded that GPC has a better performance during damage progression. Also, it was found that using slag instead of cement improved transport properties of OGPC samples at different states of damage, which leads to better durability properties. Attenuation parameter showed more sensitivity to the concrete microcracking, followed by the permeability, absorption and UPV tests, respectively. Additionally, non-destructive tests were more susceptible to this kind of damages in the perpendicular direction to loading, particularly at higher loads. Lastly, a model is proposed to relate ultrasonic measurements with permeability results, so one can predict permeability of concrete from non-destructive tests
  9. Keywords:
  10. Geopolymer Concrete ; Durability ; Permeability ; Water Absorption ; Ultrasonic Waves ; Pressure Loading ; Structural Health Monitoring ; Local Microcracking

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