Fibre Reinforced Concrete - cvut.czpeople.fsv.cvut.cz/www/dvorstom/v_frvs/Fibre_Reinforced_Concrete… · Steel – and Synthetic Fibre Reinforced Concrete . 2013©vv, CTU in Prague

2013©vv, CTU in Prague

Fibre Reinforced Concrete

This presentation was created thanks to the support of FRVŠ

project 915/2013 B1d „Tools for teaching design of concrete

and masonry structures in English“

Ing. Vladimíra Vytlačilová, PhD.


Terminology

• NSC = Normal Strength Concrete

• FRC = Fibre Reinforced Concrete

• FC = Fibre Reinforced Concrete

• SFRC = Steel Fibre Reinforced Concrete

• SFRC = Synthetic Fibre Reinforced Concrete

• GFRC or GRC = Glass Fibre Reinforced Concrete

• PPFRC = Polypropylene Fibre Reinforced Concrete


Concrete X Fibre Reinforced Concrete (FRC)

• Concrete is relatively brittle, and its tensile strength is

typically only about one tenths of its compressive strength.

• Regular concrete is therefore normally reinforced with steel

reinforcing bars.

• FRC is the concrete with small, randomly distributed fibers.

• Compared to plain concrete is FRC much tougher and more

resistant to impact.

• Their main purpose is to increase the energy absorption

capacity and toughness of the material, but also increase

tensile and flexural strength of concrete.


FRC – Historical Perpective

• BC: horse Hair, straw, feathers

• 1900: asbestos fibers, Hatscheck process

• 1950: Composite materials

• 1960: FRC

• 1970: New initiative for asbestos cement replacement

• 1970: SFRC, GFRC, PPFRC, Shotcrete

• 1990 micromechanics, hybrid systems, wood based fiber

[Source: www.bydleni.lidovky.cz ]

http://www.bydleni.lidovky.cz/


Advantage

• Better durability

• Limitations contraction cracks

• Improvement of ductility

• Improvement tensile strength

• Better fire resistance


Disadvantage

• Exacting of production technology

• Higher price (per cubic meter concrete)

• Higher specific gravity

• Corrosion of steel fibres


Fibre Reinforced Concrete (FRC)

• FRC is a structural material having nearly the same

cementitious – matrix composites as a plain concrete (PC)

except fibres of different types and forms.

• Concrete containing a hydraulic cement, water, fine or fine

and coarse aggregate, and discontinuous discrete fibers is

called fiber-reinforced concrete (FRC).

• It may also contain pozzolans and other admixtures

commonly used in conventional concrete.

• The addition of any type of fibers to plain concrete reduces

the workability.

STEEL FIBRE REINFORCED CONCRETE

Plain concrete Steel fibre reinforced

concrete

Aggregate

Steel

fibres

Cement

8/35


Fibres of various materials, shapes and sizes

• Fibres: 1. Steel fibres

2. Micro synthetic fibres

3. Macro synthetic fibres

• Produced from steel, plastic, glass, and natural materials

• For most structural and nonstructural purposes, steel fiber is

the most commonly used of all the fibers.

• Steel – and Synthetic Fibre Reinforced Concrete



• Steel Fibers

• Polyvinyl Alcohol (PVA) Fibers

• Polypropylene or Nylon Fibers

• Alkali Resistant Glass Fibers

• Cellulose Fibers

• Carbon Fibers



• Aspect Ratio = Length / Diameter

• Aspect ratio= l/d 50 - 100

• Typical aspect ratios range from about 30 to 150.


Steel Fibres

• Steel Fibres increase:

• Ductility

• Energy absorption

• Shear resistance

• Stiffness


Steel Fibres

Observations - Steel fibres

Dℓ

F

Tension

Compression

Dℓ/ℓ

s

Dℓ

F

Dℓ

ℓ

F F

Increasing fibre content

Increasing fibre content

14/3

5


Steel Fibres

Steel fibre reinforced concrete model for tensile behaviour

based on local strain


Steel Fibres

Steel fibre reinforced concrete model for tensile behaviour based

on fracture energy


Fibres

• Typical fiber types used in concrete:


Mix Design -Aggregate

• Optimization grading curve (length and quantity of fibres)

a) Short fibres

b) Low dose of fiber

c) Optimal design

d) Segregation fibres

e) Segregation

aggregate

f) Homogenous mixture


Steel Fibres

Tritreg Dramix Strax Fibrex

Material Steel Steel Steel Steel

Type

Specific

gravity 7850 kg/m3 7850 kg/m3

7850

kg/m3

7300

kg/m3

Tensile

strength 1000 N/mm2 800 N/mm2

800

N/mm2

400

N/mm2

Length 50 mm 60 mm 60 mm 35 mm


Effect of fibres type

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

34

36

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0 5,5 6,0

Průhyb [mm]

Síl

a [

kN

]

Fmax = 35,2 kN

200200 200

S

F/2 F/2

600

100 100

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

34

36

38

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0 5,5 6,0

Průhyb [mm]

Síl

a [

kN

]Fmax = 36,6 kN

200200 200

S

F/2 F/2

600

100 100

Deflection [mm]

Deflection [mm]

Lo

ad

[kN

]

Load [k

N]


Synthetic Fibres


Synthetic Fibres


Synthetic Fibres

Forta Fero BeneSteel Strax PET

Material Poly-propylene

mixture of

Polypropylene and

Polyethylene

Synthetic Poly-ethylene-

terephthalate

Type Monofilament and

polyfilament fibres

Mono-filament

fibres

Mono-filament

fibres

Mono-filament

fibres

Specific

gravity 910 kg/m3 920 kg/m3 920 kg/m3 1050 kg/m3

Tensile

strength 700 N/mm2 660 N/mm2 620 N/mm2 not known

Length 54 mm 55 mm 40 mm 80 mm


Glass Fibres

• Alkali Resistant (AR) glass fibers

It can replicate virtually any surface detail and reproduce the

appearance of materials such as stone, slate, terracotta and

marble.


Classification according to volume fraction

• Low volume fraction < 1% (reduce shrinkage cracking)

• Moderate volume fraction between 1-2% (increase the

modulus of rupture, fracture toughness, impact resistance)

• High volume fraction > 2% (strain-hardening of the

concrete)


Areas of Application 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


Areas of Application

Precast

• Wall panels

• Storage Tanks

[Source: Bosfa.com]


Application

Fibre Concrete Cornice

(Czech)



Precast

• Tunel lining Segments

[Source: Bosfa.com]



Precast

• Beams

[Source: Bosfa.com]



Precast

• Pipes

• Segments

[Source: Bosfa.com]



Ground Supported Slabs

• � Heavy parking areas

• � Drive through areas

• � Roadways

• Pavements & Roadways

[Source: Bosfa.com]



Ground Supported Slabs

• Warehouse Slabs

• Bottling Hall

• Storage Bins

[Source: Bosfa.com]



Slope Stabilisation

• Shotcrete

[Source: Bosfa.com]



Other Application

• Skate Park Reinforced with Fibres

[Source: Bosfa.com]



Other Application

• Floating islands for terns



Furniture

• Glass Fibre Reinforced Concrete



Mining

• Shocrete Application

• Tunel lined with Shocrete

• Civil Tunnelling

39

Bridge

40

Crash barrier

41

Testing of FRC

• Standard tests

• cube 150/150/150 mm

• cylinder Φ150/300 mm

• prism 150/150/700 mm

42

Calculation and design procedures

• Cross-section design in bending – FC without

reinforcement bars


Example of Typical Slide

• Thus unlike plain concrete, a fiber-reinforced concrete specimen does not break immediately after initiation of the first crack.

• This has the effect of increasing the work of fracture, which is referred to as toughness and is represented by the area under the load-deflection curve.

• In FRC crack density is increased, but the crack size is decreased.


FRC

• The most important contribution of fibres in concrete is the

flexural toughness of the material.

• When flexural strength is the main consideration, fiber

reinforcement of concrete is not a substitute for

conventional reinforcement.

• The greatest advantage of fiber reinforcement of concrete is

the improvement in flexural toughness (total energy

absorbed in breaking a specimen in flexure).


Example of Typical Slide

• The beam test results in a resistant force – deflection

diagram FR - d characterize the behaviour of FRC

specimen .

• The diagram FR - d shows two different manners of beam

specimens behaviour

• Typical load-deflection curves for plain

• concrete and fiber-reinforced concrete


Sources

• Concrete Technology, Kamran M. Nemati

• www.bosfa.com

Documents

Fibre Reinforced Concrete - cvut.czpeople.fsv.cvut.cz/www/dvorstom/v_frvs/Fibre_Reinforced_Concrete… · Steel – and Synthetic Fibre Reinforced Concrete . 2013©vv, CTU in Prague