demonstrating steel fibres from waste demonstrating steel fibres
TRANSCRIPT
Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations
Tlemat, Pilakoutas and Neocleous
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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
Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations
Tlemat, Pilakoutas and Neocleous
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OutlineOutlineWaste Tyre Recycling
Recycled Steel Fibres
Pull-out Tests
Flexural Tests
Conclusions
Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations
Tlemat, Pilakoutas and Neocleous
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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
Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations
Tlemat, Pilakoutas and Neocleous
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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™
Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations
Tlemat, Pilakoutas and Neocleous
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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.
Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations
Tlemat, Pilakoutas and Neocleous
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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
Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations
Tlemat, Pilakoutas and Neocleous
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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
Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations
Tlemat, Pilakoutas and Neocleous
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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
Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations
Tlemat, Pilakoutas and Neocleous
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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
Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations
Tlemat, Pilakoutas and Neocleous
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• 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
Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations
Tlemat, Pilakoutas and Neocleous
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• 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
Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations
Tlemat, Pilakoutas and Neocleous
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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
Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations
Tlemat, Pilakoutas and Neocleous
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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
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
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
Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations
Tlemat, Pilakoutas and Neocleous
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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
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
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
]
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%
Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations
Tlemat, Pilakoutas and Neocleous
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• 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
Demonstrating Steel Fibres from Waste Tyres as Reinforcement in Concrete: Material Considerations
Tlemat, Pilakoutas and Neocleous
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Acknowledgements
UK’s Department of Trade and
Industry