Fibre reinforced concrete

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FIBER RIENFORCED CONCRETE Created and presented by:

VAMSHI INDRALA (11E11A0196) BENJAMIN (11E11A0172) KALYANI (12E15A0106) SWAMI (11E11A0192) VANI (12E15A01241 CONTENTS

INTRODUCTIONHISTORY OF FRCWHY FRC ?PROPERTIESTYPES OF FRCTESTS ON CONCRETEAPPLICATIONSSUMMARYREFERENCESCHAPTER-1WHAT IS FRC ?

(FRC) is concrete containing fibrous material which increases its structural integrity. It contains discretefibresthat are uniformly distributed and randomly oriented.

Fibers include steel fibers,glass fibers,synthetic fibersandnatural fibers each of which lend varying properties to the concrete. Historical perspectiveThe concept of using fibers as reinforcement is not new. Fibers have been used as reinforcement since ancient times.

Historically,horsehairwas used inmortarand strawinmudbricks. In the 1900s,asbestosfibers were used in concrete.

In the 1950s, the concept ofcomposite materialscame into being and fiber-reinforced concrete was one of the topics of interest.

By the 1960s,steel,glass (GFRC), and synthetic fibers such aspolymerfibers were used in concrete. Research into new fiber-reinforced concretes continues today.

WHY FRC . . . ?Improves toughness of concreteFlexural strength is increases up to 30% by decreasing the propagation of cracksImproves tensile strengthMore economical than regular steel reinforcementLess prone to corrosionGives an alternative way to reinforce concrete other then traditional steel rebar

FIBER PROPERTIES

There are several primary properties necessary for a material to make an adequate fiber:

Fiber length to width ratioFiber uniformityFiber strength and flexibilityFiber elasticity andFiber cohesiveness.Types of fibers include SteelPlasticPolyester, Polypropylene, PolyethyleneGlassNatural materialsWood cellulose, Bamboo, Elephant grass

STEELPLASTICNATURALGLASSPOLYMERVARIOUS TYPES OF FIBRES Fiber reinforced concrete is the composite material containing fibers in the cement matrix in an orderly manner or randomly distributed manner. Hence Its properties would obviously, depends upon the efficient transfer of stress between matrix and the fibers. The factors are briefly discussed Factors affecting properties of FRC Factors affecting properties of FRC

Relative fiber-matrix stiffness Volume of fibers Aspect ratio of the fiber Orientation of fibers Workability of compaction of concrete Size of coarse aggregate MixingRelative Fiber Matrix Stiffness : The modulus of elasticity of matrix must be much lower than that of fiber for efficient stress transfer. because low modulus fibers are unlikely to give proper strength.Volume of Fibers: the increase in the volume of fibers, increases the tensile strength and toughness of the composite. Use of higher percentage of fiber is likely to cause segregation and harshness of concrete.Aspect Ratio of the Fiber: increase on the aspect ratio increases the ultimate concrete linearly. Beyond 75, relative strength and toughness is reduced. Below Table shows the effect of aspect ratio on strength and toughnessType of concreteAspect ratioRelative strengthRelative toughnessPlain concrete011With251.52.0Randomly501.68.0Dispersed fibers751.710.5Orientation of Fibers: It was observed that the fibers aligned parallel to the applied load offered more tensile strength and toughness than randomly distributed or perpendicular fibers.

Workability : consequence of poor workability is non-uniform distribution of the fibers. Generally, the workability and compaction standard of the mix is improved through increased water/ cement ratio or by the use of some kind of water reducing admixturesSize of Coarse Aggregate: Maximum size of the coarse aggregate should be restricted to 10mm, to avoid appreciable reduction in strength of the composite. Fibers also in effect, act as aggregate. Although they have a simple geometry, their influence on the properties offresh concreteis complex. CHAPTER-2steel fibers have been used for a long time in construction of roads and also in floorings, particularly where heavy wear and tear is expected.

There are increasing numbers of tunneling projects using precast lining segments reinforced only with steel fibers.

the Blends of both steel and polymeric fibers are often used in construction projects in order to combine benefits of both products; structural improvements provided by steel fibers and the resistance to explosive spalling and plastic shrinkage improvements provided by polymeric fibersSTEEL FIBRES

properties of SFRCImprove structural strengthReduce steel reinforcement requirementsImproveductilityReduce crack widths and control the crack widths tightly, thus improving durabilityImprove impact and abrasionresistanceImprove freeze-thaw resistance.Glass fiber reinforced concrete, also known asGFRCorGRC, is a type of fiber reinforced concrete.

Glass fiber concretes are mainly used in exterior building faade panels and Somewhat similar materials arefiber cement siding.

Glass fiber reinforced concrete consists of high strengthglass fiber embedded in a cementiousmatrix.GLASS FIBRES

propertiesTensile and flexural strength

Short-term temperature resistance

Long-term creep and fatigue resistance

Polymeric fibers are being used now because of their no risk of corrosion and also being cost effective. Polymeric fibers normally used are either of polyester or polypropylene. Polymer fiber reinforced concrete (PFRC) was used on two sites with ready mix concrete and Vacuum dewatering process.Polymer Fiber

properties of Polymer Fiber

Improve freeze-thaw resistance

Improve resistance to explosivespallingin case of a severe fire

Improve impact resistance

Improve mix cohesion, improving pumpability over long distances

Increase resistance to plastic shrinkage during curing

NATURIAL FIBERS natural fiber may be chemically more inert than either steel or glass fibers.

They are also cheaper, especially if natural. A large volume of vegetable fiber may be used to obtain a multiple cracking composite.

The problem of mixing and uniform dispersion may be solved by adding a super plasticizer

BAMBOO AND ELEPHANT GRASS is very similar to that of concrete

Susceptible to volume changes in water

Increases ultimate tensile strength

Elephant Grass :

Very durable good rot and alkali resistant

Increases flexural and impact strength

CHAPTER-3TESTS ON CONCRETECONCRETE SLUMP TEST COMPRESSIVE STRENGTH TESTIn order to differentiate the FRC from OPCC concrete we have to perform certain tests mentioned below.hence after conducting these tests the results conclude that the there is an considerable differences in workabilities and compressive strengths of various concretes.CONCRETE SLUMP TEST

This test is performed to check the consistency of freshly made concrete. The slump test is done to make sure a concrete mix is workable. The measured slump must be within a set range, or tolerance, from the target slump.

Procedure of Slump Test for Concrete

STEP 1: CLEANINGClean the cone. Dampen with water and place on the slump plate. The slump plate should be clean, firm, level and non-absorbent. Collect a sample of concrete to perform the slum test.

STEP 2:FILLINGThe mould is then filled in four layers. Stand firmly on the foot pieces and fill 1/4 the volume of the cone with the sample.

STEP 3:COMPACTIONEach layer shall be compacted with tamping rod by 25 strokes.

STEP 4:LEVELLINGLevel off the surface with the steel rod using a rolling action. Clean any concrete from around the base and top of the cone, push down on the handles and step off the foot pieces.

Carefully lift the cone straight up making sure not to move the sample.Turn the cone upside down and place the rod across the up-turned cone.

STEP 5:MEASURING THE SLUMP VALUETake several measurements and report the average distance to the top of the sample. If the sample fails by being outside the tolerance (i.e. the slump is too high or too low), another must be taken. If this also fails the remainder of the batch should be rejected.

VARIATION OF SLUMP VALUES OF OPCC GFRC AND FRCCHAPTER-4COMPRESSIVE STRENGTH TESTThe testing is done in a laboratory off-site. The only work done on-site is to make a concrete cube for the compression testa characteristic strength of concrete measured at 28 days after mixing is considered

Cube casting

CURING TANKCURING OF BLOCKS

Digital compression testing machine

Procedure for Compressive strength of ConcreteSTEP 1: CLEANINGClean the cube mould and coat the inside lightly with form oil, then place on a clean, level and firm surface, i.e. the steel plate. Collect a sample.

STEP 2:FILLINGThe mould is then filled in three layers. Fill 1/3 the volume of the mould with concrete then compact by tamping 35 times. Cubes may also be compacted by vibrating using a vibrating table.

STEP 3:COMPACTIONFill the cone to overflowing and tamping 35 times into the top of the first layer, then top up the mould till overflowing.

STEP 4:LEVELLINGLevel off the top with the steel float and clean any concrete from around the mould.STEP5:SETTING AND TESTINGput it in a cool dry place to set for at least 24 hours.After the mould is removed the cube is sent to the laboratory where it is cured and crushed to test compressive strength

No of daysSamplesWeight of block(Kg)Compressive strength of OPCC (N/mm2)7 dayStrengthS18.2219.00S28.1220.12S38.1120.32Avg19.81No of daysSamples Weight of block(Kg)Compressive strength of GFRC (N/mm2)7 day strengthS18.0119.32S28.1021.47S38.1320.35Avg20.38No of daysSamples Weight of block(Kg)Compressive strength of SFRC (N/mm2)7 day strengthS18.0122.10S28.1221.42S38.2021.91Avg21.81VARIATION OF STRENGTHS OF OPCC GFRC AND SFRCCHAPTER-5Runway, Aircraft Parking, and PavementsCounter tops and other furniture worksTunnel Lining and Slope StabilizationBlast Resistant StructuresThin Shell, Walls, Pipes, and ManholesDams and Hydraulic StructureOther Applications include machine tool frames, lighting poles, water and oil tanks and concrete repairs.Applications of FRC It increases the tensile strength of the concrete.It reduces the air voids and water voids the inherent porosityof gel.It increases the durability of the concrete.Fibers like glass have excellent resistance to creep.deformations of concrete are minimized.

NECESSITY OF FRCFiber reinforced concrete is one of the oldest methods for reinforcing concreteThe main purpose of FRC is to increases its structural integrity and improve flexural behavior There are many different types of fiber that can be used for concrete reinforcement. Is an economical way to use FRC.Summary REFERENCESWikipedia, the free encyclopediayoutubeVarious websitesApplications FRC ASSOSIATION.

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Chart1605852484640282616

OPCCGFRCSFRCTIMESLUMP VALUS IN mmslump values of OPCC, GFRC, SFRC

Sheet1OPCCGFRCSFRCinitial60585230min4846401hr282616To resize chart data range, drag lower right corner of range.