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1 Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Characterisation Houssam Tlemat Research scholar Kypros Pilakoutas Professor of Construction Innovation Kyriacos Neocleous Kyriacos Neocleous Marie-Curie Post-doctoral Research Fellow Centre for Cement and Concrete, Department of Civil and Structural Engineering, The University of Sheffield, UK http:/www.shef.ac.uk/tyre-recycling

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Page 1: Demonstrating Steel Fibres from Waste Demonstrating …ci.group.shef.ac.uk/files_RT_site/IMTCR_04_HT.pdf · Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete:

Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

1

Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete:

Material Characterisation

Houssam TlematResearch scholar

Kypros PilakoutasProfessor of Construction Innovation

Kyriacos NeocleousKyriacos NeocleousMarie-Curie Post-doctoral Research Fellow

Centre for Cement and Concrete, Department of Civil and Structural Engineering, The University of Sheffield, UK

http:/www.shef.ac.uk/tyre-recycling

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Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

2

OutlineOutlineWaste Tyre Recycling

Recycled Steel Fibres

Pull-out Tests

Flexural Tests

Conclusions

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Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

3

EU Average Tyre Statistics 2002

Material recovery

21%

Retreading12%

Export, reuse11%Landfill,

stockpile34%

Energy recovery

22%

Waste Tyre RecyclingWaste Tyre Recycling

• International Problem:

1 billion annual arisings worldwide

Quarter of this amount arises in EU

• EU directives driving force for waste management

• Landfill directive prohibits disposal of tyre by-products by 2006

• Develop new markets to avoid disposal

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Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

4

Material Recovery:Material Recovery:• Mechanical processes (e.g. tyre shredding)reduces tyres to steel fibres & granulated rubber

• Thermal degradation processes (e.g. microwave induced pyrolysis)breaks down tyres into steel, char, liquids and gases

Waste Tyre RecyclingWaste Tyre Recycling

AMAT LTD™

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Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

5

Patent Applied ForPatent Applied For

The University of Sheffield has The University of Sheffield has filed a patent application for the filed a patent application for the Use of Tyre Fibres in Concrete.Use of Tyre Fibres in Concrete.

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Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

6

Pyrolysed Recycled Steel Fibre (PRSF)• Clean from rubber• Tensile properties not affected (1250 MPa)• Fibres contain carbon black on surface• Fibre not so easy to cut

Examined FibresExamined Fibres

12 wires (φ0.23mm) twisted to a core strand (φ0.85mm), surrounded with another 15 twisted wires. On the surface there is a twisted single wire.

Overall external diameter: 1.55 mm

Effective diameter: 1.16 mm

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Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

7

Shredded Recycled Steel Fibre (SRSF)• Fibres contain small amounts rubber and fluff• Long bid wires need to be removed (sieving)• Fibres are magnetised

Examined FibresExamined Fibres

• Fibres tend to ball-up• Inconsistent size and shape • Diameter ~ 0.23mm

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Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

8

Industrially Available Steel Fibre (ISF)

• Fibre industrially produced from wire with flattened ends

• Fibre is rigid

• Diameter: 1mm

• Tensile Strength: 1150 MPa

Examined FibresExamined Fibres

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Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

9

Why ? • Useful to understand fibre bond characteristics

• Determination of the critical fibre length

Problems: • Not always easy to perform on fibres (high accuracy required for very small displacement and load)

• No standard method

• A suitable test must be developed for each fibre

PullPull--out Testsout Tests

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Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

10

• Specimen Preparation:

DoubleDouble--sided Pullsided Pull--out Testsout Tests

Perspex plate with ISF

10mm plastic tubes filled with silicon were used

Nominal size 100x100x80 mm

Casting done in two stages

Lemb

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Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

11

• Specimen Preparation:

Steel clamps are fixed at the end of each specimen. Deformation is measured over a gauge length of 50mm using two transducers.

Applied LoadFixed part

Perspex plate

Concrete specimen Tested fibre

LVDT

DoubleDouble--sided Pullsided Pull--out Testsout Tests

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Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

12

1. 5 kN strain gauged spring beam2. Chuck attached the clamp with a pin3. Fixed metal clamp pinned on the chuck4. Perspex plate with the fibre through its

central holes placed in middle of specimen5. 230 volt Single Phase Motor fitted with 3-

step pulley drives the cross-head at a speed of 1.5 mm/min

6. Pulled part of the specimen 7. Cross-head attached to motor8. Manual handles

DoubleDouble--sided Pullsided Pull--out Testsout Tests

1 2 3 4 5 6 7 8

• Test set-up

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Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

13

Test Results for PRSF and ISF fibres

(10 mm embedment length)

• PRSF fibre has better bond at the initial stages

• Bond resistance of ISF provided by end anchorage

DoubleDouble--sided Pullsided Pull--out Testsout Tests

0

0.1

0.2

0.3

0.4

0 2 4 6 8 10

SLIP [mm]

LOA

D [k

N]

PRSFISF

B1

C1

D1A

B2

C2

D2

l = 10mm

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Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

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Effect of aspect ratio - PRSF and ISF fibres

DoubleDouble--sided Pullsided Pull--out Testsout Tests

0

400

800

1200

1600

0 5 10 15 20 25 30ASPECT RATIO l/d

TEN

SIL

E S

TRES

[MP

a]

1-ISF average of 3-PRSF 1-PRSF 1-PRSF with end anchoring • Peak tensile stress increases linearly with the aspect ratio

• Better behaviour for PRSF with end anchoring

• Critical length: more than 60mm PRSF, but for practical reasons, 50 mm recommended

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Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

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Test results for shredded fibres

• The tested 0.23mm diameter shredded fibres are very fragile

• Only fibres with 10mm embedment length pulled out during loading

• All fibres with 20mm and 30mm embedded length fractured during loading

DoubleDouble--sided Pullsided Pull--out Testsout Tests

0

20

40

60

80

100

0 2 4 6 8 10 12

SLIP [mm]

LOA

D [N

]

10 mm 20 mm 30 mm

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Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

16

Why ? • Examine the toughness and energy absorption capacity of steel fibre reinforced concrete

• Determination of design parameters

Problems: • Results prone to experimental errors

• Variety of testing methods

Flexural Toughness TestsFlexural Toughness Tests

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Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

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Flexural Toughness TestsFlexural Toughness TestsSpecimen preparation:• Accurate deflection measurement – using a yoke • 150 x 150 x 550 mm specimens • Crack inducer: 25 x 4mm notch at mid-span• Four point loading – 100 kN servo-hydraulic machine – crack

mouth opening displacement

LVDT on each side

PinsAluminium barLVDT

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Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

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Flexural Toughness TestsFlexural Toughness Tests• Effect of fibre volume (average of 3 tests)

Peak load and residual strength after cracking increase with fibre volume.

0

10

20

30

40

50

60

70

0 1 2 3 4Average mid-span deflection [mm]

PRSF 1.5%

PRSF 3%

PRSF 6%

SRSF 0.5%

SRSF 1%

SRSF 2%

ISF-1 6%

Ave

rage

load

[kN

]

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Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

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Flexural Toughness TestsFlexural Toughness TestsEffect of fibre type:(average of 3 tests)

• Response just after peak load is stable for PRSF and ISF fibres

• PRSF is comparable to ISF

01020304050607080

0 0.5 1 1.5 2 2.5 3DEFLECTION [mm]

LOA

D [k

N]

SRSF 2%PRSF 6%ISF 6%

0

5

10

15

20

25

30

0 1 2 3Deflection [kN]

Load

[kN

]

PRSF 1.5%

SRSF 2%

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Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

20

• Tensile strength of tested fibres is influenced by the pull-out test method used

• Double-sided pull out tests eliminate measurement errors

• If possible, PRSF should be provided with end anchorage

• PRSF has stiffer initial bond-slip characteristics than the ISF fibre

• An increase in fibre volume increases the flexural toughness significantly

• PRSF and ISF exhibit good energy absorption capacity

ConclusionsConclusions

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Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations

Tlemat, Pilakoutas and Neocleous

21

Acknowledgements

UK’s Department of Trade and

Industry