Use of Fiber-Reinforced SCC for the Repair of Reinforced ... · PDF fileASTM C 1621 Modified ... 3 x 12 mm bars for SCC ... Effect of longitudinal SCC with FRP bars type CC with FRP

ACI Spring Convention – Minneapolis April 14, 2013 1

Use of Fiber-Reinforced SCC for the Repair of Reinforced Concrete Beams

Kamal Khayat, Missouri University of Science & Technology

Fodhil Kassimi, Université de Sherbrooke, Canada

ACI Spring Convention

Minneapolis - April 15, 2013

Building construction

Precast architectural

applications

Hydro-electric facilities

Mass foundations

Building construction

Transportation structures

NSERC High-Performance Flowable Concrete

with Adapted Rheology

Infrastructure

rehabilitation

Flowable mass

concrete

Semi-flowable

SCC

SCC FR-SCC

MO-S MU-S ST

Fiber type and characteristics

ST-PP

Synthetic

92% steel +

8% polypropylene

Hybrid Metallic

Lf (mm) 40 50 5-15 and 42 30

Lf / df 90 74 47 55

Ef (GPa) 9.5 5 203 (steel portion) 200

Monofilament Multifilament Hooked ends

Objectives

Compare performance of

various types of FR-SCC

Compare performance of SCC,

FR-SCC, and CVC

Experimental program

Parameters

Repair material

Concrete (SCC) vs. mortar (CEM)

Reinforcement

Fiber type (steel, synthetic, and hybrid)

Fiber volume

0.3% and 0.5% for FR-SCC

1.4% for CEM

3 rebars in repair zone for SCC vs. 2 rebars for FR-SCC

Typical mixture proportioning

Ref. SCC ST 0.5%

w/cm 0.42 0.42

Binder (GUb-S/FS) (kg/m3) 475 475

Paste volume (binder + water + air)

(L/m3)

415 415

Crushed coarse aggregate, 5-10 mm

(L/m3)

290 273

Sand-to-aggregate ratio (by volume) 1.00 1.07

Air content (%) 5.9 7.0

Slump flow (mm) 720 705

Workability

characteristics & test

methodsDeformability

Passing ability

Filling capacity

Stability

Rheology

Consolidation protocol

of SF-FR-SCC and

risk of segregation

Hardened propertiesCompressive strength

Splitting tensile strength

Avg. residual strength

Drying shrinkage

Restrained shrinkage

Flexural creep

Testing and performance of FR-SCC

Workability assessment

Slump flow vs. fiber factor

R2= 0.88

R2= 0.92

400

500

600

700

800

0 10 20 30 40 50 60 70

Vf L f / d f

Slump-flow (mm)

MO-S MU-S MI-MA ST-PP ST

Synthetic fibers

Metallic &

hybrid fibers

Modified J-Ring setup for FR-SCC and FR-CEM

ASTM C 1621 Modified

Clear spacing 43 ± 1.5 mm 2.5 × Lf � 125 ± 15 mm

No. of bars 16 8

ASTM C 1621 J-Ring test setup Modified J-Ring with 8 bars

Modified J-Ring spread vs. fiber factor

R2 = 0.86

R2 = 0.91

350

450

550

650

750

0 10 20 30 40 50 60 70

Vf Lf / df

J-Ring spread (mm)

MO-S MI-S MI-MA ST-PP ST

Synthetic fibers

Metallic &

hybrid fibers

Clear spacing 2.5 × Lf � 125 ± 15 mm

No. of bars 8

D

a

R2 = 0.80

0

5

10

15

20

25

0 10 20 30 40 50 60 70

Vf Lf / df

D / a


Clear spacing 2.5 × Lf � 125 ± 15 mm

No. of bars 8

Modified L-box setup for fibrous mixtures (FR-SCC and FR-CEM)

Free spacing between bars = {1 bar for FR-SCC

80 mm ≈ 2.5 × Lf for FR-SCC (modified box)

3 x 12 mm bars for SCC

35 mm for SCC (conventional box)

Blockage of FR-SCC

Surface Settlement

0.0

0.1

0.2

0.3

0.4

0.5

0 2 4 6 8 10 12 14 16 18

Age of concrete (h)

Settlement (%)

ST-PP 0.75%

ST 0.75%

SCC

ST-PP 0.5%MO-S 0.5%

MO-S 0.75%

ST 0.5%

No clear relation of settlement between SF-FR-SCC and FR-SCC

SF-FR-SCC

Workability requirements SF-FR-SCC FR-SCC

Slump flow (mm)

J-Ring (D/a)

V-funnel (sec)

L-box blocking ratio

Filling capacity (%)

Surface settlement (%)

500 – 600

7-12

> 7

0.2 – 0.6

40 – 50

≤ 0.5

600 – 730

12-23

≤ 7

0.6 – 1

50 –100

≤ 0.5

Typ. workability characteristics forSF-FR-SCC and FR-SCC

Compressive strength

35

40

45

50

55

0 10 20 30 40 50 60 70

Vf Lf / df

21d-f' c (MPa)


Slight strength drop with MO-S and ST fibers at 0.75% Vf (lack of consolidation)


3.5

4.5

5.5

6.5

0 10 20 30 40 50 60 70

Vf Lf / df

21d-f' sp (MPa)


Slight strength drop with MO-S and ST fibers at 0.75% Vf (lack of consolidation)

Initial loading

Re-loading

(MPa)

+++=

2

25.100.175.050.0

.4

)(

db

LPPPPARS

Deflection rate = 0.65 mm/min

Average residual strength (ASTM C 1399-04) (toughness)

Average residual strength

0

1

2

3

4

5

0 10 20 30 40 50 60 70

ARS (MPa)

Vf Lf / df


* Vf = 0.25%, 0.5% and 0.75% for MO-S and ST* Vf = 0.5% and 0.75% for MU-S, MI-MA and ST-PP

Drying shrinkage (Monolifament synthetic fibers)

0

300

600

9000

30

60

90

120

150

180

210

240

270

300

330

360

390

Time of exposure (days)

Drying shrinkage (µm/m)

SCC

MO-S 0.25%

MO-S 0.5%

MO-S 0.75%

Drying shrinkage(Multifilament synthetic fibers)

0

300

600

900

0

30

60

90

120

150

180

210

240

270

300

330

360

390



SCC

MU-S 0.5%

MU-S 0.75%

Drying shrinkage(80% macro – 20% micro synthetic fibers)

0

300

600

9000

30

60

90

120

150

180

210

240

270

300

330

360

390



SCC

MI-MA 0.5%

MI-MA 0.75%

Drying shrinkage(92% steel – 8% polypropylene fibers)

0

300

600

900

0

30

60

90

120

150

180

210

240

270

300

330

360

390



SCC

ST-PP 0.5%

ST-PP 0.75%

Greater area refers to

better performanceHRWRA

21d-ARS

21d-f’sp

Slump flow

Filling capacity

Shrinkage

Overall performance evaluation using “close-loop’’ plot

Overall performance

SF-FR-SCC has lower performance than SCC and FR-SCC

MO-S MU-S

ST

ST-PP

Monofilament Multifilament

Workability



Passing ability

Filling capacity

Stability

Rheology

Consolidation of SF-

FR-SCC




Drying shrinkage


Flexural creep

Structural performanceMonolithic beams

Repaired beams


Monolithic

Beams

(2 bars)

Repair beams (2

bars)

(CVC base)

2 CVC (ref.)

SCC SCC

SCC3 (3 bars)

MO-S 0.3%

MO-S 0.5% MO-S 0.5%

ST-PP 0.3%

ST-PP 0.5% ST-PP 0.5%

ST 0.3%

ST 0.5% 2 ST 0.5%

ST 1.4% (CEM)

3100

1050250 500 1050 250

250

400 2 Νο.10Μ

8 mm @ 150 mmNo. 20M varies (2 to 3)φ

Workability characteristics of the investigated beam mixtures

Mixture

Slump-flow

(mm)

J-Ring (m

m)

Air volume

(%)

V-Funnel (s)

L-box h 2/h

1

Filling

capacity (%)

CVC 110 -- 7 -- -- --

SCC 720 715 5.9 2.7 0.99 100

MO-S 0.3% 710 700 8.9 3 1 97

MO-S 0.5% 700 680 9 4.1 0.91 93

ST-PP 0.3% 705 700 6.3 3 0.96 97

ST-PP 0.5% 700 675 6.6 4.8 0.90 90

ST 0.3% 715 708 6.8 3 0.98 97

ST 0.5% 705 687 7 3.6 0.92 95

ST 1.4% 720 716 9 1.8 0.98 96

Effect of concrete type

CC SCC

Effect of fiber

contribution

MO-S 0.5%

MU-S 0.5%

ST-PP 0.5%

ST 0.5%

Effec

t of fiber

type

Effect of fiber

contribution

MU-S 0.5%

ST 0.5%

Effect of

longitudinal bars

type

SCC with FRPEffect of longitudinal

bars type

CC with FRP

Effect of range

of flowability

SF-SCC

ST ≥ 0.75%

SF-SCC

MU-S ≥ 0.75% Effec

t of fiber

type

CC

Rep

rese

ntative

mea

n

Effec

t of fiber

type

FRP: Fiber-reinforced polymer

CVC: Conventional vibrated concrete

SF-SCC: Semi-flowable self-consolidating concrete

Red: already tested

Black: to be tested

Ongoing work (13 monolithic beams)

CEM: Concrete equivalent mortar

Red: already tested

Black: to be tested

SCC

Effect of fiber

contribution

MO-S 0.5%

MU-S 0.5%

ST-PP 0.5%

ST 0.5%

Effec

t of fiber type

Effect of reinforcement

density

SCC with 3

longitudinal barsEffect of mixture

nature

CEM

ST 1.4%

MO-S 0.3%

MU-S 0.3%

ST-PP 0.3%

ST 0.3%

ST 0.5%

Rep

rese

nta-

tivem

ean

Effect of stay-in-

place formwork

performance

SCC

ST 0.5%

Effect of fiber

contribution in

the repair

material

Rep

rese

nta-

tivem

ean

MU-S 0.5%

Effec

t of fiber

type

Effect of fiber

volume

Ongoing work (15 repaired beams)

Repair procedure

Covering reinforcement in repair

zone with duct tapePlacing PVC duct (150 mm) in

inverted reinforcing cage

Sealing placement ducts from both ends

Holes

140 mm diameter

900 100

125

1000 250

400

Normal concrete

100 1000

Repair procedure

Casting of CC

substrate

Repair procedure

Spraying substrate with set

retardant shortly after casting

Water-jetting after 1 day to remove

surface mortar

Interface cleaned and duct tape removedPVC mold removed

Repair procedure

Lifting of inverted and partially cast

beam for intermediary preparations Breaking and removing the PVC molds

Mechanically roughened hole surface to increase bonding quality

Repair procedure

+

Wet curing of substrate concrete (CVC) for 14 days

Return to normal position for repair

Repair procedure

Wet curing of repaired beam for 14 days

Curing of repair beams

Air-curing in laboratory till flexural

testing (6 months)

Workability characteristics

Mixture

Slump-flow

(mm)

J-Ring

(mm)

Air volume

(%)

V-Funnel

(s)

L-box h 2/h

1

Filling

Cap. (%)

CVC 110 -- 7 -- -- --

SCC 720 715 5.9 2.7 0.99 100

MO-S 0.3% 710 700 8.9 3 1 97

MO-S 0.5% 700 680 9 4.1 0.91 93

ST-PP 0.3% 705 700 6.3 3 0.96 97

ST-PP 0.5% 700 675 6.6 4.8 0.90 90

ST 0.3% 715 708 6.8 3 0.98 97

ST 0.5% 705 687 7 3.6 0.92 95

ST 1.4% 720 716 9 1.8 0.98 96

Cores for compression (100×200 mm)

Core through hole filled

with repair concrete (A) P PCore from hole filled with

repair concrete (B)

(D = 95 mm)

Cores for compressive strength

@ A: mean (f’c core / f’c cylinder) = 1

@ B: mean (f’c core / f’c cylinder) = 0.92

0.70

0.80

0.90

1.00

1.10

f'ccore/ f'ccylinder

1.00

0.97 1.01

0.91

1.04

0.95

1.07

1.03

Point A

0.94

0.91

0.89

0.84

0.91

0.93

1.04

0.88

Point B

Loading and strain-control systems

2 strain-gauges for reinforcement

P

2 strain-gauges for concrete

250 250

400

5001050 1050

2 LVDT

P

Load vs. mid-span deflection (repair beams)

0

50

100

150

200

250

300

0 10 20 30 40 50 60 70 80 90

Deflection (mm)

SCC 2bars

SCC 3barsUltimate load

Yield load

Crack load

Load (kN)

Summary of mechanical loads for monolithic beams (2 bars)

0

50

100

150

200

250

300

Load (kN)

45 55 60

Crack load

153

150

192

Yield load

216

219 248

Ultimate load

Load vs. mid-span deflection (ref. beam and repair beams : 2 bars)

0

50

100

150

200

250

300

0 10 20 30 40 50 60 70 80 90

Deflection (mm)

CVC (mono ref.)

MO-S 0.3% MO-S 0.5%

ST-PP 0.3% ST- PP 0.5%

ST 0.3% ST 0.5%

ST 1.4%

Load (kN)

Summary of mechanical loads (ref. beam and repair beams)

0

50

100

150

200

250

300

Load (kN)

45 50

50 56 58

55 57 65

60 62

Crack load

153

148

213

150

151

157

152 169

176

182

Yield load

216 230

267

206

213

204 230

227

224

216

Ultimate load

Repaired / mono CVC beams increase: crack

load: 10% to 40%

yield load: up to 40%

ultimate load: up to 25%

Load vs. crack width

0

50

100

150

200

250

300

0 2 4 6 8 10 12

Load(kN)

Crack width (mm)

CVC (mono)

ST-PP 0.3% ST-PP 0.5%

MO-S 0.3% MO-S 0.5%

ST 0.3% ST 0.5%

ST 1.4% (CEM)

Crack width

Repaired / mono CVC beams decrease: 15% to 60% lower (mean of 40%)

Toughness and stiffness

Increase in repair beam loads compared to CVC

Toughness: -1% to 26% (mean of 13%)

Stiffness : -4% to 21% (mean of 6%)

0

4000

8000

12000

16000

Property values

11824

13542

12793

12122

13705

13179

11725 14529

14937

13542

Toughness (N.m)

7679

7707

8216

7313

8332

7432

7363 9264

9318

8424

Stiffness (kN.m²)

0

50

100

150

200

250

Strain (µm/m)

CC (mono)

MO-S 0.3% MO-S 0.5%

ST-PP 0.3% ST-PP 0.5%

ST 0.3% ST 0.5%

ST 1.4% (CEM)

Concrete Reinforcement

18000

-6000

-4000

-2000 0

2000

4000

6000

8000

10000

12000

14000

16000

Load(kN)

Load vs. strains (2 bars)

Reinforcement and concrete strains

Repaired / mono CVC beams - reinforcement strains 80% to 120% (mean of 99%)

concrete strains 70% - 135% (mean of 96%)

0

500

1000

1500

2000

2500

3000

µstrain

2300

2383

1838

2414 2734

2403

2366

2280

2092

1926

Reinforcement (tension)

800

615

573

1067

903

884

841

748

530 731

Concrete (compression)

Crack pattern appraoch

CVC (mono. ref.)

SCC

SCC3

Crushing

Crack pattern approach

CVC (mono. ref.)

MO-S 0.3%

MO-S 0.5%

Spalling Crushing

Crack pattern

monolithic CVC beam ST 0.5% beam

Repaired beams had less crack network and crack width than monolithic CVC

beams

Monolithic CVC beams underwent both substantial crushing and spalling at

failure; whereas repaired beams exhibited only crushing

Number of major cracks in monolithic CVC beam is higher than that in repaired

beams


CVC (mono. ref.)

ST-PP 0.3%

ST-PP 0.5%

Spalling Crushing


CVC (mono. ref.)

ST 0.5%

ST 0.3%

ST 1.4% (CEM)

Spalling Crushing

Overall structural performance

Beam

Crack Load(kN)

Yield Load(kN)

Ultimate Load(kN)

Reinf.Strain(µm/m)

Concrete strain (µm/m)

Crack widh (mm)

Toughnrss(N.m)

Stiffness (kN.m²)

CVC (ref.) 45 153 216 2300 -800 0.62 11824 7679

SCC 50 148 230 2383 -615 0.183 13542 7707

SCC3 (3 bars) 50 213 267 1838 -573 0.187 12793 8216

MO-S 0.3% 56 150 206 2414 -1067 0.283 12122 7313

MO-S 0.5% 58 151 213 2734 -903 0.231 13705 8332

ST-PP 0.3% 55 157 216 2403 -884 0.366 13179 7432

ST-PP 0.5% 57 152 204 2366 -841 0.374 11725 7363

ST 0.3% 65 169 230 2280 -748 0.286 14529 9264

ST 0.5% 60 176 227 2092 -530 0.204 14937 9318

ST 1.4% (CEM) 62 182 224 1926 -731 0.094 13542 8424


Greater area refers to

better performance Crack load

Reinforcement strain

Crack width

Stiffness Yield load

Ultimate load

Concrete strain

Toughness


0.32

0.41

0.630.51

0.41

0.87

0.971.00

Example of beam ST 0.3%

Area×E-4= 12059


ACI 318 [2008] CSA-A23.3-06 AASHTO [2005] ACI 363 [2008]

Beam Service lo

ad(k

N)

∆ex

p(m

m)

∆exp/ ∆the

Mea

n

C.O

.V.

∆exp/ ∆the

Mea

n

C.O

.V.

∆exp/ ∆the

Mea

n

C.O

.V.

∆exp/ ∆the

Mea

n

C.O

.V.

Monolith

ic aCVC1 92 4.2 1.38

1.37

24

1.33

1.32

23

1.40

1.37

26

2.35

2.52

33

CVC2 89 2.9 1.02 0.98 1.04 1.80

SCC 90 3.8 1.90 1.79 1.98 3.97

bMO-S 0.5% 100 3.9 1.51 1.46 1.46 2.81

ST-PP 0.5% 104 3.8 1.37 1.33 1.34 2.49

ST 0.5% 115 3.6 1.03 1.01 1.01 1.72

Rep

air

aSCC 89 4.0 2.64

1.80

25

2.45

1.74

22

2.76

1.78

24

5.96

3.46

34

SCC3 128 5.4 1.75 1.76 1.80 2.67

b

MO-S 0.3% 95 4.5 2.10 2.00 1.90 4.05

MO-S 0.5% 91 3.7 1.83 1.74 1.78 3.71

ST-PP 0.3% 94 4.4 2.12 2.03 1.94 4.17

4.182.04ST-PP 0.5% 91 4.3 2.08 1.97

ST 0.3% 101 3.8 1.47 1.43 1.34 2.65

ST 0.5% 106 3.8 1.26 1.23 1.24 2.22

ST 0.5% (d) 101 4.3 1.52 1.47 1.42 2.62

ST 1.4% 109 4.5 1.24 1.30 1.62 2.40

a: Fibrous beams; b: Non fibrous beams

Deflection predictions (monolithic vs. repair beams)

δexp/δthe(1)

CodeACI 318

[2008]

CSA-A23.3-

06

AASHTO

[2005]

ACI 363

[2008]

Beams

Mea

n

C.O.V.

Mea

n

C.O.V.

Mea

n

C.O.V.

Mea

n

C.O.V.

6 Monolithic 1.37 24 1.32 23 1.37 26 2.52 33

10 Repair 1.80 25 1.74 22 1.78 24 3.46 34

(1) Deflection values corresponding to 60% of yield load value.

Deflection predictions(monolithic vs. repair beams)

Inconservative deflection values with all code provisions (the codes do not provide a margin of security.)

Better correlation of δexp/δthe with monolithic beams than repairdones

Better correlation with CSA-A23.3-06 code and lower correlationwith ACI 363

Mean δexp/δthe of all used codes was 1.64 for repair ST 1.4% vs. 2.24 for all other repair beams du to high fiber volume used in this CEM.

Deflection predictions(monolithic vs. repair beams)

Deflection predictions (non-fibrous vs. fibrous beams)

ACI 318 [2008] CSA-A23.3-06 AASHTO [2005] ACI 363 [2008]

Beam Service lo

ad(k

N)

∆ex

p(m

m)

∆exp/ ∆the

Mea

n

C.O

.V.

∆exp/ ∆the

Mea

n

C.O

.V.

∆exp/ ∆the

Mea

n

C.O

.V.

∆exp/ ∆the

Mea

n

C.O

.V.

Non-fib

rous

c

CVC1 92 4.2 1.38

1.74

35

1.33

1.66

33

1.40

1.80

36

2.35

3.35

50

CVC2 89 2.9 1.02 0.98 1.04 1.80

SCC 90 3.8 1.90 1.79 1.98 3.97

2.76d

SCC 89 4.0 2.64 2.45 5.96

SCC3 128 5.4 1.75 1.76 1.80 2.67

Fib

rous

c

MO-S 0.5% 100 3.9 1.51

1.59

24

1.46

1.54

22

1.46

1.55

21

2.81

3.00

29

ST-PP 0.5% 104 3.8 1.37 1.33 1.34 2.49

ST 0.5% 115 3.6 1.03 1.01 1.01 1.72

d

MO-S 0.3% 95 4.5 2.10 2.00 1.90 4.05

MO-S 0.5% 90 3.7 1.83 1.74 1.78 3.71

ST-PP 0.3% 94 4.4 2.12 2.03 1.94 4.17

ST-PP 0.5% 91 4.3 2.08 1.97 2.04 4.18

ST 0.3% 101 3.8 1.47 1.43 1.34 2.65

ST 0.5% 106 3.8 1.26 1.23 1.24 2.22

1.47 1.42 2.62ST 0.5% (d) 101 4.3 1.52

ST 1.4% 109 4.5 1.24 1.30 1.62 2.40

c: Monolithic beams; d: Repair beams

δexp/δthe(1)

Code ACI 318

[2008]

CSA-

A23.3-06

AASHTO

[2005]

ACI 363

[2008]

BeamMea

n

C.O.V.

Mea

n

C.O.V.

Mea

n

C.O.V.

Mea

n

C.O.V.

5 Non-fibrous 1.74 35 1.66 33 1.80 36 3.35 50

11 Fibrous 1.59 24 1.54 22 1.55 21 3.00 29

(1) Deflection values corresponding to 60% of yield load value.

Deflection predictions(non-fibrous vs. fibrous beams)

Inconservative deflection values with all code provisions

ACI 363 underestimates highly deflection value

Better correlation of δexp/δtheo with fibrous beams than non-fibrous ones

Better correlation with CVC type

Predicted deflection is more correlated with beam repaired with FR-CEM

Deflection predictions(non-fibrous vs. fibrous beams)

Stiffness predictions(monolithic vs. repair beams)

Rexp/Rthe

Code ACI 318

[2008]

CSA-A23.3-

06

AASHTO

[2005]

ACI 363

[2008]

Beams

Mea

n

C.O.V.

Mea

n

C.O.V.

Mea

n

C.O.V.

Mea

n

C.O.V.

6 Monolithic 0.61 23 0.67 22 0.60 24 0.34 29

10 Repair 0.46 21 0.51 20 0.45 22 0.24 29

Stiffness predictions(non-fibrous vs. fibrous beams)

Rexp/Rthe

Code ACI 318

[2008]

CSA-A23.3-

06

AASHTO

[2005]

ACI 363

[2008]

Beams

Mea

n

C.O.V.

Mea

n

C.O.V.

Mea

n

C.O.V.

Mea

n

C.O.V.

5 Non-fibrous 0.49 36 0.54 33 0.48 37 0.28 43

11 Fibrous 0.53 22 0.59 21 0.51 21 0.28 30

P exp(kN)

P ACI318 (kN)

Pexp/PACI318

Mea

n

C.O

.V.

P ACI544 (kN)

Pexp/ PACI544

Mea

n

C.O

.V.

M

NC 45 55 0.82

0.85

7.26

-- --

0.69

36.98SCC 55 73 0.75 -- --

ST 0.5% 58 66 0.88 101 0.59

MO-S 0.5% 58 66 0.88 47 0.50

ST-PP 0.5% 60 67 0.90 33 0.98

R

SCC 54.8 73.2 0.75

0.83

18.92

-- --

1.31

65.88

SCC3 38.8 73.2 0.53 -- --

PP-1 0.3% 44.0 67.1 0.66 26.3 1.67

PP-1 0.5% 55.9 69.5 0.81 47.2 1.19

ST-PP 0.3% 57.6 67.8 0.85 18.4 3.13

ST-PP 0.5% 55.1 66.5 0.83 33.2 1.66

ST 0.3% 61.0 66.2 0.92 52.9 1.15

ST 0.5% 67.0 64.9 1.03 101.0 0.66

ST 0.5% (d) 55.0 62.5 0.88101.0 0.54

126.0 0.51ST 1.4% 64.3 65.0 0.99

Crack load predictions(monolithic vs. repair beams)

ACI 318 code provides better predictions for crack laod than ACI 544 code

Pexp/Pthe

Code ACI 318

[2008]

ACI 544

[2008]

Beams

Mea

n

C.O.V.

Mea

n

C.O.V.

6 Monolithic 0.85 7

0.69 37

10 Repair 0.83 19 1.31 66

Crack load predictions(monolithic vs. repair beams)

ACI 318 provided the best predictions for crack load

Workability



Passing ability

Filling capacity

Stability

Rheology

Consolidation of SF-

FR-SCC




Drying shrinkage


Flexural creep

Structural performanceMonolithic beams

Repaired beams


1.

Development

of mix design

of FR-SCC

2. Necessary

modifica-

tions to

workability

tests

3. Mechanical

properties (f’c,

f’sp, Ec, and fr)

Scope of Research

4. Drying

shrinkage

5. Restrained

shrinkage

6. Flexural

creep7. Durability 8. Repair

methodo-logy

10. Flexural

perfor-mance

of monolithic

and repaired

beams

9. Consolida-

tion of

SWC/FR-

SWC

Load Frames for Flexural Creep

Adjustments before

measurements

Drying shrinkage

Mechanical

properties Reference beam

Loaded Mirror Frame System Under Four-Point Bending

Test

Basis

Supports

Bolt

Upper beam

Lower beam

Principal lever

Lower roller

Load beam4 3 2 1

Secondary lever

Square plate

Steel rod

2 columns

Roller supports

Stems & chain

Ball

Load

Fiber Types and Characteristics

MO-S MU-S STMI-MA ST-PP

Synthetic

92% steel +

8% polypropylene

Hybrid Metallic

Lf (mm) 40 50 20 and 50 5-15 and 42 30

Lf / df 90 < 100 74 < 100 84 < 100 47 < 100 55 < 100

Ef (GPa) 9.5 5 7.2 (macro

portion)

203 (steel portion) 200

Shape Straight Straight Tissue-crimped Micro-crimped Hooked

20% micro +

80% macro

Monofilament Multifilament

• 1 day in formwork (beams) and molds (cylinder and prisms

specimens)

• 6 days under wet burlap and plastic sheets (beams and

cylinders) and in wet curing (drying shrinkage prisms)

• Up to 16 months in a temperature-and humidity-controlled room

at 23 ± 2 oC and 50% ± 4% RH

Curing Method

+ or

0

3

6

9

0 60 120 180 240 300 360 420 480

Time (day)

Deflection (mm)

SCC ST 0.5%MU-S 0.5% MU-S 0.5%-EASCM ST 0.8% CVC ST 0.5%

1

2

3 2

43

2

1

1

2

31

Long-Term Deflection

1: 5 kN (in av., Msus = 0.35 Mcr) 2: 16 kN (in av., Msus = Mcr)

3: 23 kN (in av., Msus = 1.4 Mcr) 4: 30 kN (in av., Msus = 1.9 Mcr)

Msus: Sustained moment Mcr: Cracking moment

0

500

1000

1500

2000

0 60 120 180 240 300 360 420 480

Age (day)

Steel µstrain


Long-Term Reinforcement Strains

0

500

1000

1500

2000

2500

3000

0 60 120 180 240 300 360 420 480

Age (day)

Concrete µstrain


Long-Term Concrete Strains

0.00

0.10

0.20

0.30

0.40

0.50

0 60 120 180 240 300 360 420 480

Age (day)

Crack width (mm) SCC

ST 0.5%MU-S 0.5%MU-S 0.5%-EACVC ST 0.5%SCM ST 0.8%

2

4 3

2

13

31

Long-Term Crack Width

Overall performance for Long-Term Deflection

at 23 kN

0.18

0.93

1.661.25

0.000.00

1.00

2.00

SCC

MU-

S 0.

5%

MU-

S 0.

5%-E

A

ST 0

.5%

SCM

ST

0.8%

Relative overall performance

2.85 0 00

SCM ST 0.8% 360 d-deflection

(×2)

360-d concr. strain

(×3)

360 d-reinf. strain

(×1)

360 d-crack width

(×3)

Relative performance vs. CVC ST 0.5%

Controlled-load bending test on

reference beams Load-controlled loading system

Instantaneous Four-Point Bending Test for Reference

Beams

2 strain gauges for concrete

500 500 150 500 150 P/2 P/2

2 strain gauges for reinforcement

180

2 LVDT 750 750

2 LVDT for cracks

Load and Strain-Control Systems for Instantaneous

Four-Point Bending Test for Reference Beams

Deflection

0

20

40

60

80

0 5 10 15 20 25Deflection (mm)

Load (kN)

SCC ST 0.5%

MU-S 0.5% MU-S 0.5%-EA

CEM ST 0.8% CVC ST 0.5%

Reinforcement and Concrete Strains

0

20

40

60

80

-5000 0 5000 10000 15000 20000

µstrain

Load (kN)

SCCST 0.5%MU-S 0.5%MU-S 0.5%-EACEM ST 0.8%CVC ST 0.5%Steel Concrete

Crack Width

0

20

40

60

80

0 1 2 3 4

Crack width (mm)

Load (kN)

SCC

ST 0.5%MU-S 0.5%

MU-S 0.5%-EACEM ST 0.8%

CVC ST 0.5%

Overall Performance for Instantaneous Deflection

(Verification at 23 kN : 1.4 Mcr)

Relative performance vs. CVC ST 0.5%

0.00

1.99 2.13 2.03

1.12

0.00

1.00

2.00

3.00

SCC

MU-

S 0.

5%

MU-

S 0.

5%-E

A

ST 0

.5%

SCM

ST

0.8%

Relative overall performance

3.00 0

0

0

SCM ST 0.8% Deflection (×2)

Concr. strain (×3)

Reinf. strain (×1)

Crack width (×3)

FR-SCC exhibits good performance in the fresh and hardened

states and is suitable for repair applications

Repair beams exhibited better overall structural performance than

monolithical beams made with CVC

Repair beams with steel fibers had better performance than the

other beams repaired with SCC containing synthetic and hybrid

fibers both for 0.3% and 0.5% fiber volumes

Incorporation of steel fibers in SCC can decrease mid-span

deflection (up to 25%), strain in concrete (30%), strain in steel

reinforcement (20%), and crack width (80%)

Major findings

• Performance in flexural creep (long term) corresponds to:

– instantaneous flexure performance (concrete/steel strain,

deflection, and crack width)

– restrained shrinkage performance (time-to-cracking, crack

width, ring micro-strain at cracking moment, and shrinkage

under sealed and unsealed conditions)

Overall performance of FR-SCC with steel fibers is 25% greater

than FR-CVC

Major findings for flexural creep

Conclusions

• Cracking of SCC (0.48 mm) > ACI 318-11 cracking limits (0.3 to 0.4 mm) >

cracking of FR-SCC and FR-SCM (0.09 to 0.19 mm)

• FR-SCC + EA � best combination (improvement in overall performance by up

to 80%). AE can reduce drying shrinkage (up to 17%), mid-span deflection

(23%), concrete strain (10%), steel reinforcement strain (12%), and crack width

(40%)

Conclusions

• FR-SCM (Vf = 0.8%) can resist well cracking, despite high drying shrinkage

due to absence of coarse aggregate

• Stress relaxation can lead to reduction of steel reinforcement strains (up to

70%), concrete strain (15% to 30%), crack width (25% to 65%), and mid-

span deflection (20% to 45%)

• Best overall performance for flexural creep: [FR-SCC + EA] > [FR-SCC] >

FR-SCC. Overall structural performance of FR-SCC (with/without EA)

under flexural creep can vary between 5 to 10 times that of SCC without

fibers

Owners:

Material Suppliers:

Engineering Firms:

Testing Labs:

Industrial Research Chair on High-Performance

Flowable Concrete with Adapted Rheology (2008-13)

Inspecsol

Prefab:

Documents

Use of Fiber-Reinforced SCC for the Repair of Reinforced ... · PDF fileASTM C 1621 Modified ... 3 x 12 mm bars for SCC ... Effect of longitudinal SCC with FRP bars type CC with FRP