frc presentation

8/13/2019 FRC Presentation

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Fibre Reinforced Concrete

BY

ANAND

KIT


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Seminar Overview at a Glance

Introduction

What is FRC ?

Types of FRC Behavior of FRC

Properties of FRC

Applications of FRC Conclusion


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Concrete

Cement

Fine Aggregate


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Concrete

Advantages

Can be cast in diverse shapes

High compressive strength

High stiffness

Low thermal and electrical conductivity

Low combustibility and toxicity .


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Concrete

Limitations

Weak in Tension

It is Brittle in nature

How to overcome theselimitations ???


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NowFibre

Reinforced

ConcreteComes to Picture


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Special Features of FRC

Thinner & Stronger Element

Reduce Weight of the structureControl cracking by adding small amount of fibres

Increases the Tensile strength

Increases Toughness

Increases Flexural strength


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For Effective use of fibres in hardened

concrete Fibres should be significantly stiffer than the matrix,ie a higher modulus of elasticity.

Fibre content byv o l u m e

must be adequate.

There must be a good fibre-matrix bond.

Fibre length must be sufficient.

Fibres must have a high aspect ratio


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Types of Fibres

Metallic

NaturalGlass

Polymeric


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Metallic Fibres

Made of either carbon steel or stainless steel

Tensile strength ranges from 345 to 1380 MPa

Minimum strength specified is 345 MPa

Modulus of Elasticity is about 200 GPa

Cross section of fibre may be circular, crescentshaped, square, or irregular

Length of fibre is normally less than 75 mm

Length to diameter ratio ranges from 30 to 100 ormore


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Metallic Fibres - Steel

Have rough surface hooked ends or are crimped orundulated through their length

Manufactured from drawn steel wire, from slit sheetsteel or by the melt-extraction process whichproduces fibres that have a crescent-shaped crosssection

Steel fibres have equivalent diameters (based oncross sectional area) of from 0.15 mm to 2 mm andlengths from 7 to 75 mm


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Metallic Fibres - Steel


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DuctilityShear resistanceEnergy absorption

StiffnessSteel fibre as supplementary reinforcementin concrete could assist in the reduction ofspalling due to thermal shock and

thermal gradients.

Advantages of Steel Fibres


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Aspect ratio is defined as the ratio betweenfibre length and its equivalent diameter, which isthe diameter of a circle with an area equal to thecross-sectional area of the fibre.

Aspect ratios generally range from 20 to 100.

Stainless steel fibres have been used for high-temperature applications.

Aspect Ratio


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Polymeric Fibres

Polymeric or synthetic fibres are man-made fibresresulting from research and development in thepetrochemical and textile industries Two different physical fibre forms :

monofilament fibres fibres produced from fibrillated tape

Two synthetic fibre volumes used in application,namely :

low-volume percentage (0.1 to 0.3% byvolume)

high-volume percentage (0.4 to 0.8% by

volume).


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Polymeric Fibres

Acrylic

Aramid

Nylon

Polyester

Polyethylene

Polypropylene

Carbon


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Polymeric Fibres - Carbon

It is substantially more expensive than other fibretypes

Available in a variety of forms and have a fibrillar

structure similar to that of asbestos Available as continuous strands or as individual

chopped fibres

High tensile strength and modulus of elasticity and abrittle stress-strain characteristic


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Comparison of Concrete and Carbon-Fiber

Reinforced Concrete

Factor Conventional Concrete Carbon Fiber Reinforced Concrete

Weight Difficult to transport Easier to transport with 50% less

weight

Damage Quality control problems,corner damage andcracking during handling

Better quality control, tougher andhence easier to handle

Formability

Bar arrangement isdifficult, formation of ribs isdifficult

Casting and molding of complexarchitectural forms is possible,increased used in decorative outcrops


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Samples of various fibre reinforced plasticreinforcements (Picture courtesy ISIS Canada)


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Glass Fibre

Alkali-resistant glass fibre is used in the

manufacture of glass-reinforced cement (GRC)products, which have a wide range of applications.

Advantages of Glass Fibre

Lightweight Durable

Paintable

Impact Resistant Waterproof

Repairable
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Use of FRC panels in theKita Kyusho Prince Hotel
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Natural Fibres

Natural reinforcing materials can be obtained atlow cost and low levels of energy using localmanpower and technology

Two types of natural fibres : Unprocessed natural fibres Processed natural fibres

Unprocessed natural fibresCoconut coir, sisal fibres, sugarcane bagassefibres, bamboo fibres, jute fibres, flax andvegetable fibres


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Sisal-fibre reinforced concrete has been used formaking roof tiles, corrugated sheets, pipes, silos andtanks

Elephant-grass-reinforced mortar has been usedfor low-cost housing projects

Wood-cellulose-fibre-reinforced cement hascommercial applications in the manufacture of flatand corrugated sheet and non-pressure pipes

Applications of Natural Fibres


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Behavior of FRC

Stress - Strain behaviorUnder Tension

Under Compression

Torsion

Flexural

Toughness

Aspect ratio


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Stress - Strain behavior - Under Tension

Under high tensile load FRC will show more deformation thanplain concrete


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Stress - Strain behavior - Under Compression

As percentage of fibre increases, compressive stress increases


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Torsional

behavior of FRC


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Flexural behavior of FRC

Addition of fibres increases the moment carrying capacity of flexural

members


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Toughness

As the Volume of fibre is increased , toughness increases.

FRC is able to sustain load at deflection or strains much greater thanthose at which cracking first appears in the matrix


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Type of fibers used.Volume percent of fiber.

Aspect ratio (the length of a fiberdivided by its diameter).Orientation of the fibers in the matrix.

Properties influencing toughness andmaximum loading of FRC are


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Application of Various Fibres in Cement Products*

FibreType

Application

Glass Precast panels, curtain wall facings, sewer pipe, thin concrete shell roofs, wallplaster for concrete block.

Steel Cellular concrete roofing units, pavement overlays, bridge decks, refractories,

concrete pipe, airport runways, pressure vessels, blast-resistant structures, tunnellinings, ship-hull construction.

Popypr opylene,nylon

Foundation piles, prestressed piles, facing panels, flotation units for walkways andmoorings in marinas, road-patching material, heavyweight coatings for underwaterpipe.

Asbestos

Sheet, pipe, boards, fireproofing and insulating materials, sewer pipes, corrugatedand flat roofing sheets, wall lining.

Carbon Corrugated units for floor construction, single and double curvature membranestructures, boat hulls, scaffold boards.

MicaFlakes Partially replace asbestos in cement boards, concrete pipe, repair materials.


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Physical and Mechanical Properties of Selected Fibres.

FibreDiameter

mSpecificGravity

FailureSrain, %

Modulus ofElasticity, GPa

TensileStrength, GPa

Steel 5-500 7.8 3-4 200 1-3Glass 9-15 2.6 2-3.5 80 2-3

Polypropylene 7.5 0.9 20.0 5 0.5

Mica

Flakes 0.01-200 2.9 -- 170 0.25

Asbestos 0.02-20 2.5-3.4 2.3 200 3

Carbon 7.5 1.7-2.0 0.5-1.0 300-400 2-3


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Conclusion

Innovations in engineering design, which often establish the need

for new building materials, have made fibre-reinforced cements verypopular

The possibility of increased tensile strength and impactresistance offers potential reductions in the weight and thickness ofbuilding components and should also cut down on damage

resulting from shipping and handlingAlthough ASTM C440-74a describes the use of asbestos-cement

and related products, there are, at this time, no general ASTMstandards for fibre-reinforced cement, mortar and concrete.

Until these standards become available, it will be necessary to

rely on the experience and judgement of both the designer and thefibre manufacturer. The onus is thus on the designer to be aware ofthe limitations presently inherent in some of these composites,particularly the durability of glass-fibre-reinforced products.


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