The Design of Concrete Pavements and maintenance.ppt

Nice

1. BY
DR. L. R. KADIYALI
Highway Engineering Consultant
1

2. LOADING
PROPERTIES OF SUBGRADE
PROPERTIES OF CONCRETE
EXTERNAL CONDITIONS
JOINTS
REINFORCEMENT
2

3. 1.WHEEL LOAD AND ITS REPETITIONS
2.AREA OF CONTACT OF WHEEL
3.LOCATION OF LOAD WITH RESPECT TO SLAB
3

4. 1.SUBGRADE STRENGTH AND PROPERTIES
2.SUB-BASE PROVISION OR OMISSION
4

5. 1.STRENGTH
2.MODULUS OF ELASTICITY
3.POISSON’S RATIO
4.SHRINKAGE PROPERTIES
5.FATIGUE BEHAVIOUR
5

6. 1.TEMPERATURE CHANGES
2.FRICTION BETWEEN SLAB AND SUBGRADE
6

7. 1.ARRANGEMENT OF JOINTS
7

8. 1.QUANTITY OF REINFORCEMENT
2.CONTINUOUS REINFORCEMENT
8

9. IRC RECOMMENDS
98
th
PERCENTILE WHEEL LOAD
9

10. 0 24681012141618202224
10
20
30
40
50
70
80
90
98
100
60
%

L
E
S
S

T
H
A
N

G
I
V
E
N

A
X
L
E

L
O
A
D
AXLE LOAD (T)
10

11. TYRE PRESSURE AS PER IRC: 58 IS 0.8MPa
THUS, FOR A WHEEL LOAD OF 8T,
11
PRESSURE TYRE
LOAD WHEEL

1000Sq.cm
8
8000
AREA 
cm 8.9
2
1
π
1000
CIRCLE OF REDIUS



12. INTERIOR
LOADING
EDGE
LOADING
CORNER
LOADING
12

13. MEASURED BY PLATE LOAD TEST USING 75 cm
DIA CIRCULAR PLATE
MODULUS OF SUB-GRADE REACTION, k,
Kg/cm
2
/cm
IF 30 cm DIA PLATE IS USED,
K
75 = 0.5 K
30
13

14. CBR 2 3 45 710152050100
k (Kg/cm
2
/cm)2.12.83.54.24.75.56.46.913.922.2
14

15. 1.To provide a uniform and reasonably firm
pavement support
2.To prevent mud-pumping on clays and silts
3.To prevent or reduce frost action
4.To provide a levelling course on distorted
and undulating subgrade
5.To act as a capillary cut-off
15

16. 1.ONE LAYER OF FLAT BRICK SOLING UNDER
ONE LAYER OF WATER-BOUND MACADAM
2.TWO LAYERS OF WATER-BOUND-MACADAM
3.WELL-GRADED SOIL-GRAVEL MIXTURES
4.LIME OR CEMENT STABILISED SOIL, GIVING A
MINIMUM CBR OF 50 AFTER 7 DAYS’ CURING
5.LIME PUZZOLANA CONCRETE OR LEAN
CONCRETE
16

17. k VALUE OF
SUB GRADE
2.12.84.24.8 5.5
k VALUE OF
SUB-BASE OF
150 mm DLC
9.713.820.827.7 41.7
(MAX ALLOWED)
17

18. GENERALLY 28-DAY COMP. STRENGTH IS
USED.
M-35, M-40 CONCRETE USED.
FLEXURAL STRENGTH IS DETERMINED BY
BEAM TEST
APPROXIMATE RELATIONSHIP:
MPa 4.4
400.7f
CONCRETE 40M FOR THUS
fck0.7f
cr
cr




18

19. E = 3 x 10
5
Kg/cm
2
POISSON’S RATIO = 0.15
COEFF. OF THERMAL EXPANSION
= 10 x 10
-6
PER
o
C
19

20. SR, STRESS RATIO :
IF SR < 0.45, UNLIMITED REPETITIONS POSSIBLE
FOR SR > 0.45, IRC PROVIDES VALUES OF
ALLOWABLE REPETITIONS
STRENGTH FLEXURAL
STRESS FLEXURAL
20

21. FORMULA)(BRADBURY

2
t ΔEα
t
f
21

22. EDGE LOAD STRESS + TEMP. STRESS AT EDGE
CORNER LOAD STRESS
22

23. 1.THE CONCRETE SLAB IS HOMOGENEOUS AND ISOTROPIC
AND HAS UNIFORM ELASTIC PROPERTIES.
2.THE REACTION OF THE SUBGRADE IS VERTICAL ONLY
AND IS PROPORTIONAL TO THE DEFLECTION OF THE
SLAB. IN OTHER WORDS, THE SUPPORT PROVIDED BY
THE SUBGRADE IS SIMILAR TO THAT GIVEN BY A DENSE
FLUID AND THE SUBGRADE HAS NO SHEAR STRENGTH.
3.THE REACTION OF THE SUBGRADE AT A POINT IS EQUAL
TO K X DEFLECTION AT THAT POINT, THE CONSTANT K
BEING THE MODULUS OF SUBGRADE REACTION.
4.THE LOAD IN THE INTERIOR AND CORNER IS CIRCULAR IN
SHAPE. THE EDGE LOADING IS SEMI-CIRCULAR.
23

24. DEFLECTED SLAB
REACTION = K x DEFLECTION
24

25. THE RADIUS OF RELATIVE STIFFNESS IS
DEFINED AS:
4
K
2
μ)12(1
3
Eh
l


25

26. 1.724ha whereab
1.724ha where0.675h)h(1.6ab
:and earlier, described as are l and a E, h, μ, P, formulae, above the In
1/222





































































2.1
3.0
3
2
2
2104
3
102
2
1
4
3
102
)2(
)1(12
1
3
0792.1
1
loglog)54.01(529.0
54.54log)1(275.0
a
Eh
K
h
P
f
b
Kb
Eh
h
P
f
C
C
l
Kb
Eh
h
P
fi
c
e




26
C
1
and C
2
are correction factors to allow for a redistribution of
subgrade reactions. C
1
can be taken to be equal to 5 l and C
2
can be
assumed to have a value of 0.2.

27. 27

28. JOINTS IN CONCRETE SLABS ARE OF
FOUR TYPES:
1.EXPANSION JOINTS
2.CONTRACTION JOINTS
3.WARPING JOINTS
4.CONSTRUCTION JOINTS
5.LONGITUDINAL JOINTS
28

29. 29

30. 30

31. 31

32. SLAB
THICKNESS
(mm)
SPACING
(m)
15-25
30
35
4.5
5.0
5.0
32

33. SLAB
THK.
(mm)
DIA.
(mm)
LENGTH
(mm)
SPACING
(mm)
20
25
30
35
25
25
32
32
500
500
500
500
250
300
300
300
33

34. SLAB
THK.
(mm)
DIA.
(mm)
LENGTH
(mm)
SPACING
(mm)
15
20
25
30
35
10
12
16
16
16
560
640
800
800
800
830
900
1280
1060
910
34

35. THANKS
35