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Fiber Reinforced Concrete

Fiber Reinforced Concrete

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Fiber Reinforced Concrete

  1. 1. DR B R AMBEDKAR NATIONAL INSTITUTE OF TECHNOLOGY DEPARTMENT OF CIVIL ENGINEERING PRESENTATION ON : FIBER REINFORCED CONCRETE SUBMITTED TO: SUBMITTED BY : DR KANISHK KAPOOR BHANVAR CHAND MEENA
  2. 2. Contents • Introduction • why use fibers ? • Application of FRC material • Material use • Factor Affecting the Properties of FRC • Comparation between PCC and FRC • Advantage and Disadvantage of FRC • Conclusion
  3. 3. INTRODUCTION • Concrete is strong in compression but weak in tension. As concrete is brittle material the failure in concrete due to tension is sudden. There are also cracks in concrete due to shrinkage and these micro cracks propagate and leads to failure. • To safeguard the concrete against flexural cracks fibres are used in concrete section which is known as fibre reinforced concrete.
  4. 4. Why use fiber ? • Fibers are used in concrete to control cracking due to plastic shrinkage and to drying shrinkage. They also reduce the permeability of concrete and thus reduce bleeding of water. • Cracks in reinforced concrete members extended freely until encountering a rebar. • Fiber reinforced concrete is used when there is requirement for elimination small cracks.
  5. 5. Applications of FRC materials • Thin sheets • Roof tiles • Pipes • Prefabricated shapes • Panels • Slabs on grade • Precast elements • Impact resisting structures
  6. 6. Fiber- reinforced concrete (FRC) Fiber- reinforced concrete (FRC) is concrete containing fibrous material which increases its structural integrity. It contains short discrete fibres that are uniformly distributed and randomly oriented. Fibres include steel fibres, glass fibres, synthetic fibres and natural fibres – each of which lend varying properties to the concrete. In addition, the character of fibre-reinforced concrete changes with varying concretes, fibre materials, geometries, distribution, orientation, and densities.
  7. 7. Types of fiber used in FRC • Steel Fiber Reinforced Concrete • Polypropylene Fiber Reinforced (PFR) concrete • Glass-Fiber Reinforced Concrete • Asbestos fibers • Carbon fibers and Other Natural fibers
  8. 8. Steel Fiber Reinforced Concrete • Diameter Varying from 0.3-0.5 mm. (IS:280-1976) • Length varying from 35-60 mm. • Various shapes of steel fibers.
  9. 9. Material Used • Cement • water • Coarse aggregates • Fine aggregates • Steel fibres
  10. 10. Factors affecting the Properties of FRC • Volume of fibers • Aspect ratio of fiber • Orientation of fiber • Relative fiber matrix stiffness
  11. 11. Volume of fiber • Low volume fraction (less than 1%) Used in slab and pavement that have large exposed surface leading to high shrinkage cracking • Moderate volume fraction(between 1 and 2 percent) Used in Construction method such as Shortcrete & in structures which requires improved capacity against delamination, spalling & fatigue. • High volume fraction(greater than 2%) Used in making high performance fiber reinforced composites.
  12. 12. Aspect Ratio of fiber • It is defined as ratio of length of fiber to it’s diameter (L/d). • Increase in the aspect ratio upto 75,there is increase in relative strength and toughness. • Beyond 75 of aspect ratio there is decrease in relative strength and toughness.
  13. 13. Orientation of fibers • Aligned in the direction of load • Aligned in the direction perpendicular to load • Randomly distribution of fibers
  14. 14. Relative fiber matrix • Modulus of elasticity of matrix must be less than of fibers for efficient stress transfer. • Low modulus of fibers imparts more energy absorption while high modulus fibers imparts strength and stiffness. • Low modulus fibers e.g. Nylons and Polypropylene fibers • High modulus fibers e.g. Steel, Glass, and Carbon fibers
  15. 15. Comparison between Plain Concrete and Fiber Reinforced Concrete
  16. 16. Advantage of Steel fiber • High structural strength • Reduced crack widths and control the crack widths tightly, thus improving durability. • Less steel reinforcement required. • Improve ductility • Reduced crack widths and control the crack widths tightly, thus improving durability. • Improve impact– and abrasion–resistance
  17. 17. Disadvantage of FRC • Reduces the workability. • Loss of workability is proportional to volume concentration of fibers in concrete. • Higher Aspect Ratio also reduced workability.
  18. 18. Conclusion • The total energy absorbed in fiber as measured by the area under the load-deflection curve is at least 10 to 40 times higher for fiberreinforced concrete than that of plain concrete. • Addition of fiber to conventionally reinforced beams increased the fatigue life and decreased the crack width under fatigue loading. • At elevated temperature SFRC have more strength both in compression and tension. • Cost savings of 10% - 30% over conventional concrete flooring systems.
  19. 19. THANK YOU

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