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Investigating the Lowest Amount of Fibers in Improving the Strength and Ductility of Ultra-High-Performance Concrete

Kamjou, Amir Shayan | 2019

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 52669 (53)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Khaloo, Alireza
  7. Abstract:
  8. It used to be widely accepted as a virtue in engineering society that, fibers are generally used as mechanism to resist cracking and increasing the strength of concrete in some cases. Since 1990, fibers are usually used in concrete to control cracking due to plastic shrinkage and to drying shrinkage. They also reduce the permeability and bleeding of concrete. Some types of fibers produce greater impact, abrasion and shatter-resistance in concrete. Studies turn this notion to cognition that among all types of existing fibers, Steel Fiber and Polypropylene Fiber resulted the highest improved behavior in concrete. The Ultra-High-Performance Concrete which heated the debate in recent papers makes the use of 2% volumetric steel fibers as reinforcement. This thesis investigates the lowest possible amount of fibers in improving strength and ductility of Ultra-High-Performance Concrete, thus the foremost step is working with Short Steel Fibers (Hooked Shape) and Polypropylene Fibers. To improve flexural strength as well, a mixture of Self-Compact UHPC which is the combination of Portland Cement, Silica Fume, Quartz Flour, Fine Sand, High-Range Water Reducer (for better workability and Ductility), 0.22 Water/Concrete, Short Steel Fibers and Polypropylene Fiber was used. This study would provide 4 instances for each seven mixtures. Twenty-eight 10*20 cm cylindrical specimens with 0%, 0.2%, 0.4% and 0.6% volumetric percentage of short steel fibers and polypropylene fibers will construct, which are at the lowest predicted percentages with respect to ordinary 2% volumetric fiber which was used before. (4 samples for each percentage, 28 cylindrical specimens). Moreover, 2 discrete types of Panels for flexural strength evaluation purpose with dimensions of 20*60*2 cm, with the same aforementioned percentage will cast. For each percentage in flexural panels two steel fiber and two polypropylene fiber specimens would provide for three-point bending test (14 Panel Specimens). Totally, 42 Specimens (28 cylindrical Specimens + 14 panels) will be tested. Mechanical properties will be studied by conducting compressive strength and flexural toughness tests. Moreover, supportive stress-strain curves of performing compressive test, load-displacement curves for three-point bending tests and energy absorption capacity for all specimens would draw for results
  9. Keywords:
  10. Panels ; Energy Absorption ; Ductility ; Resistance ; Steel Fibers ; Polypropylene ; Very High-Strenght Concrete

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