Steel fibre reinforced concrete for slab on grade.ppt

STEEL FIBRE REINFORCED CONCRETE (SFRC). for SLABS ON GRADE. Author: Royce Ratcliffe. FIBRES REINFORCE CONCRETE. Fibres – like all reinforcement - have their greatest effect after cracking develops. X-Ray Of SFRC. COMPARING FIBRES TO CONVENTIONAL REINFORCEMENT. MODEL. F c. F t = F c

1. STEEL FIBRE
REINFORCED
CONCRETE (SFRC)
Author: Royce Ratcliffe

for
SLABS ON GRADE

2. Fibres – like all reinforcement - have
their greatest effect after cracking
develops.
FIBRES REINFORCE
CONCRETE

3. X-Ray Of SFRCX-Ray Of SFRC

4. COMPARING
FIBRES TO
CONVENTIONAL
REINFORCEMENT

5. REINFORCED CONCRETE STRESS
BLOCK
ACTUAL
Moment Capacity = F
t
x d
MODEL
F
t
F
c
F
t
= F
cd
f
c
F
t

6. FIBRE CONCRETE STRESS BLOCK
f
e
(from beam test)
EQUIVALENTACTUAL
f
c
f
t
Moment Capacity = f’
t
b.0.9D0.5D
MODEL
f’
t
F
t
F
c
0.5D
D
0.9D
 f’
t
= 1/6/0.5/0.9 = 0.37f
e
= f
e
bD
2
/6

7. DIRECT TENSION FROM REINFORCEMENT BRIDGING
CRACKS IN FLOOR SLABS WORKS TO KEEP THE CRACK
NARROW, THEREBY MAINTAINING AGGREGATE
INTERLOCK AND HENCE LOAD TRANSFER.
NECESSARY AT SAW CUTS AND INTERNAL CRACKS TO
MAINTAIN A HIGH LEVEL OF LOAD CARRYING CAPACITY
IN THE SLAB.
MESH – F
t
= A
s .
f
y
FIBRE – F
t = 0.37f
eBD
MODEL
F
t
F
c
F
t = F
cd
MODEL
F
t
F
c
F
t = F
cd
f
e
(from beam test)
EQUIVALENT
f
e
(from beam test)
EQUIVALENTEQUIVALENTMODEL
f’
t
F
t
F
c
0.5D
D
0.9D
f’
t
F
t
F
c
0.5D
D
0.9D
DIRECT TENSION

8. TESTING THE
REINFORCING
PROPERTIES OF
FIBRES

9. Beam Testing

10. ESTABLISHING REINFORCING PROPERTIES
FOR SFRC
International test methods:-
1. BEAM TESTS: Several variations on the same theme dependent on
the country of origin. I.e. a beam of prismatic cross section is loaded at
1/3
rd
points with the deflection being at a controlled rate.
Span/3 Span/3 Span/3
Width
Height
P

11. ESTABLISHING REINFORCING PROPERTIES
FOR SFRC
International test methods:-
1. BEAM TESTS: Several variations on the same theme dependent on
the country of origin. I.e. a beam of prismatic cross section is loaded at
1/3
rd
points with the deflection being at a controlled rate.
Span/3 Span/3 Span/3
Width
Height
P
f
e
Stress

12. TYPICAL BEAM TEST RESULTS
P or f
Deflection (mm)
1 2 3
First Crack
Concrete Property
P or f
.05-0.1

13. TYPICAL BEAM TEST RESULTS
P or f
Deflection (mm)
1 2 3
Strain Hardening
Strain Softening
Fibre/Matrix Property
First Crack
.05-0.1

14. BEAM TOUGHNESS TESTS
0
5
10
15
20
25
30
35
0 1 2 3 4
Deflection (mm)
L
o
a
d
(
k
N
)

0.5%(40kg/m3)Steel
0.25%(20kg/m3) Steel
1.0%(9.1kg/m3) Macrosynthetic
0.5%(4.55kg/m3) Macrosynthetic
0.25%(2.3kg/m3) Macrosynthetic

15. BEAM TOUGHNESS TESTS
0
5
10
15
20
25
30
35
0 1 2 3 4
Deflection (mm)
L
o
a
d
(
k
N
)

0.5%(40kg/m3)Steel
0.25%(20kg/m3) Steel
1.0%(9.1kg/m3) Macrosynthetic
0.5%(4.55kg/m3) Macrosynthetic
0.25%(2.3kg/m3) Macrosynthetic
0.1mm Crack width
0.3mm Crack width
1.0mm Crack Width
4.0mm Crack Width

16.  R o u n d d e t e r m i n a t e p a n e l – A S T M C 1 5 5 0

18. RDP TOUGHNESS TESTING
0
5
10
15
20
25
30
35
0 10 20 30 40 50
Deflection (mm)
L
o
a
d
(
k
N
)
0.5%(40kg/m3) Steel
0.25%(20kg/m3) Steel
1.0%(9.1kg/m3) macrosynthetic
0.5%(4.55kg/m3) macrosynthetic
0.25%(2.3kg/m3) Macrosynthetic

19. RDP TOUGHNESS TESTING
0
5
10
15
20
25
30
35
0 10 20 30 40 50
Deflection (mm)
L
o
a
d
(
k
N
)
0.5%(40kg/m3) Steel
0.25%(20kg/m3) Steel
1.0%(9.1kg/m3) macrosynthetic
0.5%(4.55kg/m3) macrosynthetic
0.25%(2.3kg/m3) Macrosynthetic
0.1mm Crack Width
0.3mm Crack Width
1mm Crack Width
13mm Crack Width

20. Square Panel

21. Efnarc panel test
European standard
EN 14488-5
The punching-flexion test is an ideal test
to check the SFRS behaviour:
1)A shotcrete tunnel ling behaves like
a slab
2)The hyperstatic test conditions allow
load redistribution
3)The test can be carried out with
mesh reinforcement



This test was introduced in 1989 by the
French Railway Authority, prior to being
accepted and promoted by EFNARC then
finally becoming a Euronorm (EN) in 2006.

22. E f n a r c p a n e l t e s t

23. EFNARC SQUARE (INDETERMINATE) PANEL TEST
100 x 100
600 x 600
500 x 500
P
Deflection
P

24. P
Deflection
EFNARC SQUARE (INDETERMINATE) PANEL TEST
100 x 100
600 x 600
500 x 500
P
High early toughness reinforcement
Low toughness reinforcement

25. 80 J 400 J
800 J
1250 J

26. 0.5 vol %
4.55kg/m
3
1.0 vol %
9.1kg/m
3
1.0 vol %
9.1kg/m
3
0.5 vol %
4.55kg/m
3

27. 1250 J
1.0 vol %
9.1kg/m
3
0.5 vol %
40kg/m
3
POLYPROPYLENE
STEEL

28. HOW FIBRES
INCREASE
LOAD CARRYING
CAPACITY

29. 3000
150
100 x 100
3000
k = .035Nmm
3
FULL SCALE TESTING

30. THEORETICAL SLAB RESPONSE
Load
Deflection
PP
P
P(f
ft
)
f
ftf
ft
P
f
e

31. Load
Deflection
P
THEORETICAL SLAB RESPONSE
P
P
f
e
f
ft
Pf
ft
f
e

32. Load
Deflection
Ultimate Limit State
Serviceability Limit State
Material Factor
Load Factor
THEORETICAL SLAB RESPONSE

33. Ultimate
PERFORMANCE VERSUS TOUGHNESS
Load
Plain Concrete
Increasing Toughness(f
e)
Ultimate
Ultimate
Deflection

34. PARADIGM NEW
LOAD CARRYING
CAPACITY FOR FLOOR
SLABS IS A FUNCTION OF
FLEXURAL STRENGTH
& TOUGHNESS

35. Plain
Concrete
RC 60/60
30kg/m
3
RC 80/60
30kg/m
3
6
f
e
6
f
e
P
1(kN)
180
>345290
340240
P
Ult(kN)
200
ACTUAL RESULTS
f
e
= 3.48N/mm
2
f
e = 4.79N/mm
2
6
Beam Results

36. CREEP
Polymeric Materials
Creep occurs in the visco-
elastic phase between
T
glass & T
melting
Polypropylene
T
glass
= -10
0
C
T
melting
= 170-180
0
C
Creep is the term used to describe the tendency of a material to move or to
deform permanently to relieve stresses. Material deformation occurs as a result of
long term exposure to levels of stress that are below the yield or ultimate strength
of the material. Creep is more severe in materials that are subjected to heat for
long periods and near melting point.

37. CREEP

38. Creep test
0
200
400
600
800
1000
1200
0 200 400 600 800 1000 1200
days
c
r
e
e
p

i
n

1
/
1
0
0
m
m

39. THANK YOU!