Fiber reinforced concrete. 1. A PRESENTATION ON FIBER REINFORCED CONCRETE OVER VIEW SRI VENKATESWARA ENGINEERING COLLEGE PRESENTING Internal guide: P.Jhansi mam BY: CH.GOPI CHAND Civil engineering department. FIBER REINFORCED CONCRETE project At: pacific solutions(ECIL) Hyderabad, A.p. History 1900s, asbestos fibers were used in concrete. In the 1950s, the concept of composite materials came into being and fiber-reinforced concrete was one of the topics of interest.
Once the health risks associated with asbestos were discovered, there was a need to find a replacement for the substance in concrete and other building materials. By the 1960s, steel, glass (GFRC), and synthetic fibers such as polypropylene fibers were used in concrete. Research into new fiberreinforced concretes continues today. INTRODUCTION Concrete is one of the most versatile building material. Concrete is strong under compression yet weak under tension, brittle and limited ductility material.
Therefore, a form of reinforcement is needed, steel bars reinforce concrete against tension only locally. Cracks in reinforced concrete members extend freely until encountering a rebar. The need for Multidirectional and closely spaced reinforcement for concrete arises. FRC is a concrete mix that contains short discrete fibers that are uniformly distributed and randomly oriented. Types of fibers Fibers include steel fibers, glass fibers, synthetic fibers and natural fibers – each of which lend varying properties to the concrete. In addition, the character of fiber-reinforced concrete changes with varying concretes, fiber materials, geometries, distribution, orientation, and densities.
Project Title: Use of Fibers in Concrete Pavement 16. Abstract Continuously reinforced concrete pavement (CRCP) is a major form of highway pavement in Texas due to its increase in ride quality, minimal maintenance, and extended service life. However, CRCP may sometimes.
the composite (concrete and fibers) termed Vf. Vf typically ranges from 0.1 to 3%. Aspect ratio (l/d) is calculated by dividing fiber length (l) by its diameter (d). Fibers with a non-circular cross section use an equivalent diameter for the calculation of aspect ratio.
How is it Made.? Mostly the same as regular concrete fibers are spread throughout the aggregate and cement mix. Small layers of the concrete are poured on top of each other and infused with the fibers and are then connected Process is tedious and costly Big reason why this product costs so much. Fibers are usually 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.
ADVANTAGES VERY HIGH COMPRESSION STRENGTH HIGH TENSILE STRENGTH HIGH ELASTICITY MODULUS DUCTILE BEHAVIOUR HIGH DURABILITY. Mechanism Of Failure Of Concrete Cylinders Under Compression Testing 1 0%.fiber (control mix 2 3 0.25% fiber 4 0.5% fiber 1.0% fiber.Fiber fraction by weight of cement content. Mechanism Of Failure Of Concrete Cylinders Under Spilt Tensile Testing 0% fiber (control mix 0.25% fiber 0.50% fiber 1% fiber. Due to embedded nano optical glass fiber elements usually optical fibers. Light is conducted through the stone from one end to the other. For developing transparent concrete by arranging the high numerical aperture Plastic Optical Fibers (POF). AREAS OF APPLICATIONS OF FRC MATERIALS Thin sheets shingles roof tiles pipes prefabricated shapes panels shotcrete curtain walls Slabs on grade precast elements Composite decks Vaults, safes.
Impact resisting structures. Transparent Panels. Transparent Partition Wall. Sources Internet: e.html Textbook: Fundamentals of Materials Science and Engineering by William D. Callister Jr. Rethwisch Chapter 15 Technical Journal: Optics and Photonics News September 2008 issue “Using Nano-Optics to Control the Phase of Light”.
Fiber Reinforced Concrete can be defined as a composite material consisting of mixtures of cement, mortar or concrete and discontinuous, discrete, uniformly dispersed suitable fibers. Continuous meshes, woven fabrics and long wires or rods are not considered to be discrete fibers. Fiber is a small piece of reinforcing material possessing certain characteristics properties.
They can be circular or flat. The fiber is often described by a convenient parameter called aspect ratio. The aspect ratio of the fiber is the ratio of its length to its diameter.
Typical aspect ratio ranges from 30 to 150. Fiber reinforced concrete (FRC) is concrete containing fibrous material which increases its structural integrity. It contains short discrete fibers that are uniformly distributed and randomly oriented. Fibers include steel fibers, glass fibers, synthetic fibers and natural fibers.
Within these different fibers that character of fiber reinforced concrete changes with varying concretes, fiber materials, geometries, distribution, orientation and densities. Fibre-reinforcement is mainly used in shotcrete, but can also be used in normal concrete. Fibre-reinforced normal concrete are mostly used for on-ground floors and pavements, but can be considered for a wide range of construction parts (beams, pliers, foundations etc) either alone or with hand-tied rebars Concrete reinforced with fibres (which are usually steel, glass or plastic fibres) is less expensive than hand-tied rebar, while still increasing the tensile strength many times. Shape, dimension and length of fibre is important. A thin and short fibre, for example short hair-shaped glass fibre, will only be effective the first hours after pouring the concrete (reduces cracking while the concrete is stiffening) but will not increase the concrete tensile strength read more info http://theconstructor2009/10/fibre-reinforced-concrete-2. (Size: 1.87 MB / Downloads: 872) HISTORICAL DEVELOPMENT The concept of using fibres as reinforcement is not new. Fibres have been used as reinforcement since ancient times.
Historically, horsehair was used in mortar and straw in mud bricks In the early 1900s, asbestos fibres were used in concrete, and in the 1950s the concept of composite materials came into being and fibre reinforced concrete was one of the topics of interest. There was a need to find a replacement for the asbestos used in concrete and other building materials once the health risks associated with the substance were discovered. By the 1960s, steel, glass (GFRC), and synthetic fibres such as polypropylene fibres were used in concrete, and research into new fibre reinforced concretes continues today. THE MAIN PROPERTIES INFLUENCING TOUGHNESS AND MAXIMUM LOADING OF FIBRE REINFORCED CONCRETE Type of fibers used Volume percent of fiber(vf =o.1 to 3%) Aspect ratio (the length of a fiber divided by its diameter) Orientation of the fibers in the matrix Shape, dimension and length of fiber is important.
A thin and short fiber, for example short hair-shaped glass fiber, will only be effective the first hours after pouring the concrete (reduces cracking while the concrete is stiffening) but will not increase the concrete tensile strength. A normal size fibre (1 mm diameter, 45 mm length—steel or 'plastic') will increase the concrete tensile strength. (Size: 1.77 MB / Downloads: 438) Fiber Reinforced Concrete What is a Fiber?
Small piece of reinforcing material possessing certain characteristic properties. Can be circular or flat. Parameter used to describe fiber – “Aspect ratio”. Aspect ratio is ratio of its length to its diameter. Typical aspect ratio for fibers ranges from 30 to 150. What is Fiber Reinforced Concrete (FRC)? Fiber reinforced concrete (FRC) is concrete containing fibrous material which increases its structural integrity.
It contains short discrete fibers that are uniformly distributed and randomly oriented. Fibers include steel fibers, glass fibers, synthetic fibers and natural fibers. Within these different fibers that character of fiber reinforced concrete changes with varying concretes, fiber materials, geometries, distribution, orientation and densities.
Fibers used Although every type of fiber has been tried out in cement and concrete, not all of them can be effectively and economically used. Each fiber has some characteristic properties and limitations. Fibers used are- Steel fibers Polypropylene, nylons Asbestos, Coir Glass Carbon Steel Fiber Reinforced Concrete Most commonly used fiber. Round fiber of diameter 0.25 to 0.75mm. Enhances flexural, impact and fatigue strength of concrete. Used for-overlays of roads, airfield pavements, bridge decks. Thin shells and plates have also been constructed using stell fibers.
Polypropylene/Nylon Fiber Reinforced Concrete Suitable to increase impact strength of concrete. Possess high tensile strength but their low modulus of elasticity and higher elongation do not contribute to the flexural strength. Asbestos Fiber Reinforced Concrete Mineral fiber, most successful of all as it can be mixed with portland cement. Tensile strength of asbestos varies between 560 to 980 N/mm2. Asbestos cement paste has considerably higher flexural strength than portland cement paste. For unimportant concrete work, organic fibers like coir, jute and canesplits are also used.
Glass Fiber Reinforced Concrete Recent introduction. Very high tensile strength 1020 to 4080 N/mm2. Alkali resistant glass fiber has been developed. Shows comparable improvement in durability to conventional E-glass fiber. Carbon Fiber Reinforced Concrete Posses very high tensile strength 2110 to 2815 N/mm2 and Young’s modulus.
Cement composite consisting of carbon fibers show very high modulus of elasticity and flexural strength. Used for cladding, panels and shells.
Factors affecting properties of Fiber Reinforced Concrete Transfer of stress between matrix and fiber. Type of fiber. Fiber geometry. Fiber content. Orientation and distribution of fibers Mixing and compaction technique of concrete. Size and shape of aggregates.
Relative Fiber Matrix Stiffness Modulus of elasticity of matrix must be much lower than that of fiber for efficient stress transfer. Nylon and propylene fiber impart greater degree of toughness and resistance to impact. Steel, glass and carbon impart strength and stiffness to the composite. Interfacial bonds also determine the degree of stress transfer. Bonds can be improved by larger area of contact, improving frictional properties and degree of gripping and by treating steel fibers with sodium hydroxide or acetone. Volume Of Fiber Strength largely depends upon the quantity of fibers used. Tensile strength and toughness of the composite linearly increase with increase in volume of fibers.
Higher percentage of fibers is likely to cause segregation and harshness of concrete and mortar. Aspect Ratio Of Fiber One of the important factor affecting the properties and behavior of composite.
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Increase in aspect ration upto 75, increase the ultimate strength of concrete linearly. Beyond 75 relative strength and toughness is reduced. Orientation Of Fibers One of the major difference in conventional reinforcement and fiber reinforcement.
Specimens with 0.5% volume of fiber were tested and it showed that when fibers were aligned parallel to the load applied, more tensile strength toughness was seen as compared to randomly distributed and perpendicular fibers. Workability and Compaction of Concrete Use of steel fibers decrease the workability. External vibration fails to compact the concrete. Poor workability is also result of non uniform distribution of fibers. Fiber volume at which this situation is reached depends on the length and diameter of fiber used. Workability and compaction standard can be improved with help of water reducing admixture. Size Of Coarse Aggregates Maximum size of aggregates should be restricted to 10 mm.
Fibers also act as aggregate. The interparticle friction and between fibers and between fibers and aggregates controls the orientation and distribution of fibers which affect the properties of composite. Friction reducing admixtures and admixtures improving the cohesiveness can significantly improve the mix. Mixing Mixing is important to avoid balling of aggregates, segregation and to obtain uniform composite.
Increase in aspect ration, volume percentage, size and quantity of aggregates intensify the balling tendencies. A steel fiber content in excess of 2% by volume and an aspect ratio of more than 100 are difficult to mix. Addition of fibers before addition of water is important to get uniform dispersion of fibers in concrete mix.
Typical Proportions For FRC Advantages Of FRC Over Conventionally Reinforced Concrete Increased static and dynamic tensile strength. Energy absorbing characteristics and better fatigue strength. Uniform dispersion of fibers throughout the concrete provides isotropic properties. Applications Overlays of air-fields.
Road pavements. Industrial flooring. Bridge decks.
Canal lining. Explosive resistant structure.
Refractory lining. Fabrications of precast products like pipes, boats, beams, staircase steps, wall panels, roof panels, manhole covers etc. Manufacture of prefabricated formwork moulds of “U” shape for casting lintels and small beams. Applications Current development in FRC:- High fibre volume micro-fibre system.
Slurry infiltrated fibre concrete(SIFCON). Compact reinforced composites.
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High fibre volume micro-fibre system:- Can replace asbestos fibre. Improves toughness and impact strength. These properties make it attractive for thin precast products such as roofing sheets,cladding panels. Cement composites are useful for repair & rehabilitation works. Slurry infiltrated fibre concrete:- SIFCON was invented by Lankard in 1979.
Steel fibre bed is prepared and cement slurry is infiltrated. Micro-fibre contents up to about 20% by volume can be achieved. Increase in both flexural load carrying capacity and toughness. High compressive strength is achieved. Used for blast resistant structures & burglar proof safe vaults.
Compact reinforced composites(CRC):- Consist of an extremely strong,dense cement matrix. Extremely expensive. Exhibits flexural strength up to 260Mpa & compressive strength of about 200Mpa. As strong as structural steel. Can be moulded and fabricated at site. You have selected one or more posts to quote.
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