Fibre reinforced concrete

it will tell you about FRC , its properties ,advanatges & disadvantages. examples of usage of frc in india and types of fibres uses in frc

1. FIBRE REINFORCED CONCRETE MOHIT PANCHAL 15001515006 MCRM 2

2. CONTENT INTRODUCTION PROPERTIES OF CONSTITUENT MATERIALS TYPES OF FIBRES USED IN FRC METALLIC POLYMERIC CARBON GLASS NATURAL ADVANTAGES & DISADVANTAGES OF FRC APPLICATIONS OF FRC EXAMPLE OF USAGE OF FRC IN INDIA

3. INTRODUCTION Fibre reinforced concrete can be as such defined as a composite material consisting of mixtures of cement, mortar or concrete and discontinues, discrete, uniformly, dispersed fibres. Continuous meshes, woven fabrics and long wires or rods are not considered as discrete fibres.

4. PROPERTIES OF CONSTITUENT MATERIALS

5. CEMENT All types of cement can be conveniently used in fibre reinforced concrete. AGGREGATES The aggregates which are suitable for conventional concrete are suitable for FRC. The aggregates are generally divided into two categories namely fine and coarse aggregates. Fine Aggregate : Fine aggregate is needed for both FRC and fibre reinforced mortar Coarse Aggregate : Coarse aggregates which are suitable for normal concrete are suitable for FRC. However, the use of too large coarse aggregate can be detrimental to FRC as large size of coarse aggregates tends for non-homogenous . Therefore, ACI committee restricts maximum size of coarse aggregate as 19mm. ADMIXTURES The most widely used mineral admixtures are fly-ash and silica fumes. Fly ash is used to improve the workability of fresh concrete, to reduce heat of hydration, to improve economy, and to improve permeability characteristics. Silica fume is added mainly to obtain high strength. Use of mineral admixtures, especially silica fumes became more widespread after the introduction of water reducing admixtures.

6. TYPES OF FIBRES USED IN FRC METALLIC POLYMERIC CARBON GLASS NATURAL

7. METALLIC FIBRES Metallic fibres are made of steel. The tensile strength of fibres ranges from 345MPa to 1380MPa. Minimum suggested by ASTM is 345MPa. The modulus of elasticity is about 200GPa. The fibres may be rectangular, square, or irregular . The length of the fibre is normally less than 75mm. The aspect-ratio varies from 30 to 100 . VARIOUS SHAPES OF STEEL FIBRES

8. POLYMERIC FIBRES Synthetic polymeric fibres have been produced as a result of research and development in the petrochemicals and textile industries. Fibre types that have been tried with cement matrices include acrylic, aramid , nylon, polyester, polyethylene, and propylene. All these fibres have high tensile strength; however, except aramid fibres all have low modulus of elasticity. Primary limitations which comes with aramid fibres is their high cost.

9. CARBON FIBRES Carbon fibres have high modulus of elasticity and are two to three times stronger than steel. They are also very light with a specific gravity 1.9. They are also inert to most of the chemicals.

10. GLASS FIBRES Glass fibres are primarily used for glass fibre reinforced cement sheets. Regular E-glass fibres were found to deteriorate in concrete. This observation led to the development of alkali resistant AR-glass fibres. There are however two main problems in the use of glass fibres in Portland cement products, namely, the breakage of fibres and the surface degradation of the glass by the high alkalinity of the hydrated cement paste.

11. NATURAL FIBRES The oldest forms of fibre reinforced composites were made with naturally occurring fibres such as straw and horse hair. Modern technology has made it possible to extract fibres economically from various plants such as jute and bamboo to be used in cement composites. A unique aspect of these fibres is the low amount of energy required to extract these fibres. Example of Natural fibres are : Bamboo fibres , Coconut fibres & Jute fibres

12. ADVANTAGES & DISADVANTAGES OF FRC ADVANTAGES: Main role of fibres is to bridge the cracks that develop in concrete and increase the ductility of concrete elements. Improvement on Post-Cracking behaviour of concrete Imparts more resistance to Impact load Controls plastic shrinkage cracking and drying shrinkage cracking Lowers the permeability of concrete matrix and thus reduce the bleeding of water DISADVANTAGES: Increase in specific gravity of the concrete. This means that the concrete will be heavier than normal concrete in case of some fibres Proportioning the exact amount of fibres in the batch of concrete. Test have shown that a slight variation in fibres creates tremendous changes in concrete strength. Higher cost because of its control issues (production issues) as well as the cost of raw material is high. Corrosion of steel fibres.

13. APPLICATIONS OF FRC Residential : including driveways, sidewalks, pool construction with shotcrete , basements, coloured concrete, foundations, drainage, etc. Commercial : exterior and interior floors, slabs and parking areas, roadways and  Warehouse / Industrial : light to heavy duty loaded floors and roadways Highways / Roadways / Bridges : conventional concrete paving, SCC, white-toppings, barrier rails, curb and gutter work, pervious concrete, sound attenuation barriers, etc. Ports and Airports : runways, taxiways, aprons, seawalls, dock areas, parking and loading ramps. Waterways : dams, lock structures, channel linings, ditches, storm-water structures, etc. Mining and Tunneling : Precast segments and shotcrete , which may include tunnel lining, shafts, slope stabilization, sewer work, etc. Elevated Decks : including commercial and industrial composite metal deck construction and elevated formwork at airports, commercial buildings, shopping centers , etc. Agriculture : farm and animal storage structures, walls, silos, paving, etc. Precast Concrete and Products : architectural panels, tilt-up construction, walls, fencing, septic tanks, burial vaults, grease trap structures, bank vaults and sculptures

14. EXAMPLE OF USAGE OF FRC IN INDIA More than 400 tones of Shaktiman Steel Fibres have been used recently in the construction of a road overlay for a project at Mathura (UP). They have also been successfully used at the end anchorage zones of prestressed concrete girders for resisting bursting and spalling forces in bridge projects in Bangalore and Ahmedabad executed by one of the reputed construction companies. The fibres have also been used for heavy-duty industrial floors . Other projects include Samsonity Factory-Nasik, BIPL Plant- Pune , KRCLMSRDC tunnels, Natha Jakri Hydro Electric Plant, Kol HEP, Baglihar HEP, Chamera HEP, Sala HEP, Ranganadi HEP, Sirsisilam project, Tehri Dam project , Uri Dam Project, etc. Used in many tunnelling projects and for slope stabilisation in India.