steel fibre‐‐reinforced roller‐‐ compacted...

Steel Fibre‐Reinforced Roller‐Steel Fibre‐Reinforced Roller‐Compacted Concretep

Dr Kyriacos Neocleous / Harris AngelakopoulosDepartment of Civil and Structural EngineeringThe University of Sheffield, United Kingdom

Industry Seminar “Economical and sustainable pavement infrastructure for surface transport”, Pafos Cyprus, 08/04/09Fibre‐reinforced roller‐compacted concrete ‐ Dr Kyriacos Neocleous / Harris Angelakopoulos – University of Sheffield©

1

http://ecolanes.shef.ac.uk – http://www.shef.ac.uk/civil

OutlineOutline• Steel Fibre Reinforced (SFR) ConcreteSteel Fibre Reinforced (SFR) Concrete

• Roller‐Compacted Concrete (RCC)

• EcoLanes work on SFR‐RCC


2

SFRC is conventional concrete reinforced with discontinuous steel fibres


Steel Fibre Reinforced Concrete: Why use?

Concrete has low tensile strength.Hence, use SFRC:• Tensile & flexural strength improvement• Control cracking (shrinkage and structural)• Increase toughness Extended post crackingg• Enhance surface characteristics

Extended post-cracking behaviour

d

Enhanced flexural strengthFibre t

Load

SFRCtypes: •Asbestos

Deflection

High first crack strength

plain concreteAsbestos• Glass•


DeflectionPolymers• Steel

Steel Fibre Types: Industrially Produced


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Indented Cone End Paddle End Hooked Button End Crimped

Steel Fibre Types: RecycledSteel Fibre Types: Recycled

Steel fibres extracted from post consumer tyres:Steel fibres extracted from post consumer tyres:

M h i l sing

Mechanical shredding

Pro

ces

Removal of bead wire ss

ing

bead wire from truck

tyres Pro

cesIndustry Seminar “Economical and sustainable pavement infrastructure for surface transport”, Pafos Cyprus, 08/04/09

Fibre‐reinforced roller‐compacted concrete ‐ Dr Kyriacos Neocleous / Harris Angelakopoulos – University of Sheffield© 6

Steel Fibre Types: RecycledSteel fibres produced from post‐consumer tyres(http://www.shef.ac.uk/tyre‐recycling):

60

70

40

50

60

oad

[kN

]

20

30PRSF 6%ISF-1 6%ISF 2 6%

Ben

ding

lo

research proved that these fib b ff ti

0

10

0 1 2 3 4

ISF-2 6% fibres can be as effective as industrially‐produced fibres (ISF)


7

0 1 2 3 4Mid-span deflection [mm] (ISF)

SFRC Applications: Cast insitu & PrecastI d i l flIndustrial floors(slabs‐on‐grade) Highway pavements

Composite slabs

Shaft segments Barrier segmentsPipes


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SFRC properties: Generalp pFactors affecting performance of FRC:

V l f i f i i l• Volume fraction of constituent materials

• Aspect ratio (L/d) of fibre

• Physical properties of fibres and matrix

• Bond strength between constituents

Post‐cracking performance of FRC important:

• Matrix cracks long before fibre fractures• Matrix cracks long before fibre fractures

High volume fraction & L/d high performance, b d ff k bili


but adverse effect on workability

SFRC Properties: Fresh‐stateS l d fib

Fibres tend to ball:Fib i t l ki

pSteel tyre‐cord fibres

• Fibre interlocking• Prior to mixing

3

rix)

• During mixing with concreteff t d b fib t

2

2.5

nt (%

vol

of m

atr– affected by fibre geometry

– relative volume proportions of fibre and coarse aggregate

1

1.5

Max

fibr

e co

ntenfibre and coarse aggregate

– mixing sequence and duration of mixing


10

10 10 20 30 40

Coarse aggregate content (% volume of mix)

M

SFRC Properties: Fresh‐state

Fibres balling examples

Wet‐consistency concrete

D iDry‐consistency (Roller‐compacted) concrete


SFRC Properties: Compressive Behaviour•SFRC keeps integrity after failure

•Maximum strength slightly enhanced, but ‐Maximum strength slightly enhanced, but due to increase of voids ‐ decreases for high volume ratiosvolume ratios

P t k t th h dIndustry Seminar “Economical and sustainable pavement infrastructure for surface transport”, Pafos Cyprus, 08/04/09


•Post‐peak strength enhanced

SFRC Properties: Tensile Behaviour

•Increase tensile concrete strengthStress

SFRC

Plain

Increase tensile concrete strength •Improve post‐peak tensile concrete behaviour, which is dependent on

Tensile

S

pthe effective fibres crossing the crack

Tensile Strain

•There is no standard test for tensile σ‐ε of SFRC

•Flexural tests used to measure post‐cracking capacity


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4‐point flexural test

R ll C t d C tRoller Compacted Concrete


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A different kind of t !

What is Roller‐compacted Concrete (RCC)?concrete!

p ( )• ‘A relatively stiff mixture of aggregates, cementitious materials and water that is compactedcementitious materials and water that is compacted by vibratory rollers and hardened into concrete.’

• 0 slump• 0 slump

• No formwork required

• Adequate compaction is

critical


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RCC: Performance

• Flexural strength: 3.5 ‐ 7.0 MPa• Compressive strength: 25 ‐ 70 MPa • Satisfactory shear strength • High density • No formwork or finishing Main RCC

F tg

• Low water content, low w/c ratio • Aggregate interlock

Features

Aggregate interlock• Hard, durable, light‐coloured surface• Sawed joints may not be required


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• Sawed joints may not be required

RCC construction3.Placing of RCC pavement

L 100 200 t 2501.Placing of RCC

in a haul truck Layers: 100-200mm, up to 250 mm (with high density paver)

in a haul truck

2.Loading RCC in the paver

4.Rolling of RCC pavement


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F r o m m i x i n g t o r o l l i n g < 1 5 m i n u t e s

RCC: Applicationspp

DamsDamsDams

Heavy-load PavementsHeavy-load PavementsHeavy-load Pavements


18Road PavementsRoad PavementsRoad Pavements

RCC Pavements: Tackling Common Problemsg

• Span soft localised subgrades • No deformation under heavy, concentrated loads N d t i ti f ill f f l d• No deterioration from spills of fuels and hydraulic fluids

• No softening under high temperatures• No softening under high temperatures • Early strength gain• No rutting• No rutting • No settlement• No raveling of surface

Rutting

RavellingBearing capacity


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• No raveling of surface Bearing capacity failure

RCC Pavements: Proportioning of MaterialsRCC Pavements: Proportioning of Materials

dry enough for rollingg

wet enough for costgcement hydration

cost


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RCC Pavements: Constituent Materials• Binders (e.g. OPC, PFA)12 ~ 16% by mass12 16% by mass Aggregates (fine ≤ 5mm coarse ≤ 20mm)(fine ≤ 5mm, coarse ≤ 20mm)75 ~ 80% by mass

• Water 4 5 ~ 6% by massSelection criteria:

• Water 4.5 6% by masswater/cement = 0.3 ~ 0.45

• Admixtures (e g water

• Design strength

• Durability • Admixtures (e.g. waterreducing, retarding)

Diffi lt t dd fib / i f t

• Application


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• Difficult to add fibres / reinforcement

RCC Pavements: Laboratory Testing

Compaction curve

Maximum dry density, Ga = 2.81

y g

Compaction curve

2 6

2.8M

g/m

3

2.4

2.6

C d

ensi

ty, M

Compressive

2.20 2 4 6 8 10 12

RC

C

Dry density curveWet density curve

0 2 4 6 8 10 12Moisture content, %

BendingOptimum moisture content


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E L kEcoLanes work on

SFR‐RCC


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RCC Pavements: Mechanical Limitations

• Post cracking behaviourHigher deformations required by RCC industry

• Increase spacing of joints• Increase spacing of jointsAttain spacing similar to industrial floors (40 metres)?

• Better optimisation of materials/ technologies currently required to tackle global environmental issues

Possible solution SFR‐RCC


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FRC‐RCC: Challengesg

• Fibre dispersion in the mixp

• Compaction

• Specimen preparation

• Monitoring fibre dispersionMonitoring fibre dispersion

• Use of recycled fibres


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EcoLanes progress: Fibre dispersionp g p

Successful dispersion of recycled fibre at y

laboratory conditions

(up to 225 kg of fibres per m3 of RCC))


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EcoLanes progress: SFR‐RCC compactionEcoLanes progress: SFR RCC compaction

After compaction,After compaction,

recycled fibres

do not spring

backback

Compacted SFR‐RCC cube


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EcoLanes progress: Flexural characterisationp g

4‐point bending tests according to RILEMaccording to RILEM

recommendations and Japanese standardsJapanese standards


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EcoLanes progress: Bending test setupp g g p

A

150 150 150

150

125

150

25

150

AA-A

150


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EcoLanes progress: Typical 4‐point bending testp g yp p g


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EcoLanes progress: Flexural characterisation• Flexural behaviour SFR‐RCC: industrial fibres

p g

40

45

Fr: 3%

Button end: BE1/54Hooked end: HE1/50

N

25

30

35

KN) Fr: 2%

Fr: 3%

Fr: 2%

ding

load, kN

10

15

20Load

(K

Fr: 1% Fr: 1%

4‐po

int be

nd

0

5

-2 -1.5 -1 -0.5 0 0.5 1 1.5 2Average vertical displacement (mm)

Average vertical displacement mm

4


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Average vertical displacement, mm

EcoLanes progress: Flexural characterisation• Flexural behaviour SFR‐RCC: recycled fibres

p g

500100%50 %: by mass of concrete

N

300

400

requ

ency

40%

60%

80%

tive

Dist

ribut

ion

FrequencyCumulative %

30

40

Load

(kN

)

9% Fibres

6% Fibresding

load, kN

0

100

200Fr

0%

20%

40%

Cum

ulat

0

10

20

Bend

ing 6% Fibres

2% Fibres

1% Fibres

4‐po

int be

nd

0 5 10 15 20 25 30

Length, mm

00 0.2 0.4 0.6 0.8 1

Ver tical displacement (mm)

4


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EcoLanes progress: Recycled Concrete AggregatesEcoLanes progress: Recycled Concrete Aggregates

1st stage 2nd stage1 stage 2 stage


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EcoLanes progress: Flexural characterisation of SFR‐RCC with RCA

40 R‐300LECr‐28d‐RTC4‐24‐R6‐(30r‐70na)RCC with 100% na

30

35

40 R‐300LECr‐28d‐RTC4‐24‐R6‐(30r‐70na)

R‐300LECr‐28d‐RTC4‐24‐R6‐(70r‐30na)

R‐300LECr‐28d‐RTC4‐24‐R6‐(100r‐0na)

R‐300LECr‐28d‐R0‐(30r‐70na)

R 300LEC 28d R0 (70 30 )

20

25

ng load, kN

R‐300LECr‐28d‐R0‐(70r‐30na)

R‐300LECr‐28d‐R0‐(100r‐0na)

R‐LEcr300‐R0‐28d‐na

R‐LECr300‐RTC1‐15‐R6‐28d‐na

10

15Bend

in

0

5

0 1 2 3 4 5 6 7


34

0 1 2 3 4 5 6 7

Vertical displacement, mm

EcoLanes progress: Flexural characterisation of SFR‐RCC with RA RCC with 100% na

5

6

7

Pa) 5

6

7

N

R-LECr300-RTC6-25-R6-7d-ra a

R-LECr300-RTC6-25-R6-7d-ra b

R-LECr300-RTC1-15-R6-7d-na b

2

3

4

Flex

ural

stre

ss (M

P

R-LECr300-R0-7d-na bR-LECr300-R0-7d-ra aR-LECr300-R0-7d-ra bR-LECr300-RTC6-25-R6-7d-ra a

2

3

4

5

Ben

ding

load

(kN

0

1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

R-LECr300-RTC6-25-R6-7d-ra b

0

1

2

0 1 2 3 4 5 6 7 8


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Net midpoint deflection (mm)Net midpoint deflection (mm)

EcoLanes progress: DurabilityAccelerated corrosion tests 0, 5 & 10 months

p g y

recycledindustrial

5 months of corrosion0 months of corrosion 10 th f i5 months of corrosion simulation shows that

specimens with recycled fibres are the most

0 months of corrosion simulation shows RCC

specimens with 6% recycled fibres already

10 months of corrosion simulation shows an increase of

rust at the specimens with recycled fibres – specimens with


fibres are the most corroded

recycled fibres already corroded

recycled fibres specimens with industrial fibres show corroded

fibres near surface

EcoLanes progress: Durability

R-CEMII/A-L300- RTC3-11-R6 – internal viewAccelerated corrosion tests 0, 5 & 10 months

p g y

R CEMII/A L300 RTC3 11 R6 internal view

150 mm

m15

0 m

m


5 months 10 months

EcoLanes progress: DurabilityAccelerated corrosion tests 0, 5 & 10 months

p g y

Compressive strength Flexural strength14a]

.

120a] .

68

101214

reng

th [M

Pa

6080

100120

engt

h [M

Pa

0246

t l 28 5 th 10 thFl

exur

al st

r

02040

pres

sive

stre

W-LEC380-I2C1/54-R2W-LEC380-RTC3-11-R6R CEMII/A L300 I2C1/54 R2

control - 28days

5 monthscorrosion

10 monthscorrosion

control - 28days

5 monthscorrosion

10 monthscorrosionC

omp


R-CEMII/A-L300-I2C1/54-R2R-CEMII/A-L300- RTC3-11-R6

EcoLanes remaining work on SFR‐RCC

• Parametric study for SFR RCC mixes

g

• Parametric study for SFR-RCC mixes

• Durability tests (corrosion, freeze-thaw)y ( )

• Fatigue bending tests

• Modelling of SFR-RCC


This research has been financially supported by the 6th FP of the European Community within thethe 6 FP of the European Community within the framework of specific research and technological development programme “Integrating and strengthening the European Research Area” understrengthening the European Research Area , under contract number 031530.

Thank You!Thank You!Industry Seminar “Economical and sustainable pavement infrastructure for surface transport”, Pafos Cyprus, 08/04/09

Fibre‐reinforced roller‐compacted concrete ‐ Dr Kyriacos Neocleous / Harris Angelakopoulos – University of Sheffield©

Background Notes


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Steel Fibre Types: RecycledSize-reduction processes (e.g. tyre shredding):reduces tyres to steel fibres & granulated rubber.

Thermal degradation processes (e.g. microwave pyrolysis):breaks down tyres into steel, char, liquids and gases.AMAT LTD™


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SFRC Properties: Flexural Behaviour

C

Phase 1

CNA

Phase 2

CT1

NA

Phase 3C

T1T2

NA MSMM

Phase 4

T1NA

MS

T1

T2

NA

MMMS

T1

T3

T2MSMM

T2

T3

T4

MM

MS

F

Microcrack initiation

MMCrack resisted

through fibre pullout

F

Crack with not muchresistance from fibres

FFfc

NA

Ffc

Fft

NAFfc

Fft

NAFfc

Fft

NAMSMM

FZ

C: Compressive zone NA: Position of the neutral axisT1: Uncracked tensile zone MS: Max Tensile strain at σt l

Fft

FftFZ FZ FZ


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T1: Uncracked tensile zone MS: Max. Tensile strain at σt,calT2: Aggregate and fibre bond bridging zone MM: Micro-Macro zones axisT3: Fibre pull-out zone FZ: Fracture zoneT4: No resistance from fibres

SFRC Properties: Flexural BehaviourFour-point flexural tests of ISF and steel tyre-cord fib (SRSF & PRSF)fibres (SRSF & PRSF):

• Behaviour of beams 60

70

PRSF 1.5%

N]

with PRSF similar toth ith ISF

40

50 PRSF 3%

PRSF 6%

SRSF 0.5%ge lo

ad [k

N

those with ISFs

• Flexural strength 10

20

30SRSF 1%

SRSF 2%

ISF 1 6%

Ave

rag

Flexural strengthincreases with fibre content

0

10

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

ISF-1 6%


44

content g p [ ]

SFRC Design: Methods

Lack of universally accepted design standards:

g

ac o u e sa y accepted des g sta da ds• Similar concepts to conventional reinforced concrete• Provisions for flexure, shear and crackingRILEM technical committee on “Test and designRILEM technical committee on Test and design methods of steel fibre reinforced concrete”:

St k th d (f t h i )• Stress-crack, σ-w, method (fracture mechanics)• Stress-strain, σ-ε, method (based on Eurocode-2)


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( )

RCC Pavements: Construction Process

Transported by trucks

Produced in a pugmill or central mix plant or dry

trucksPlaced and compacted with an asphalt paver

central mix plant or dry batch plant

Joint spacing:

9 20 metresIndustry Seminar “Economical and sustainable pavement infrastructure for surface transport”, Pafos Cyprus, 08/04/09


Roller compactionCuring9-20 metres

RCC Pavements: Design

Thickness design approach

g

• Portland Cement Association

• US Army Corps of Engineers• US Army Corps of Engineers

• minimise, within acceptable limits, the flexural f ti d d b th h l l d thfatigue damage caused by the wheel load on the pavement over the design life

• Information required for sub‐grade, sub‐base, vehicle characteristics, RCC mechanical properties


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steel fibre‐‐reinforced roller‐‐ compacted...

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