cc pavement (revised design)

8/10/2019 CC Pavement (Revised Design)

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Pavement thickness = 150mm

From The Graph Edge load Stress (Fig 2 of SP62:2004) = 4.00 Mpa

b) Edge temparature Stress

For the state of Andhra Pradesh the temperature differentials ( Dt ) for 150mm thick slab is 17.3 oC

Alpha = Coefficient of Thermal expansion of Concrete = 10 X Power(10, -6)

(As per Clause 3.8 , page 8 of SP62:2004 )

L / l = : 5.569

W / l = : 5.569

FOR L / l = 5.569

Bradbury's coefficient C from Fig. 1, (Page 9,SP 62:2004)

By interpolation C value may be arriaved = (0.72+(0.92-0.72)*(5.569-5)/(6-5))

= 0.834

From The Graph Edge Temperature Stress (Fig 1, page 9 of SP62:2004) = 2.15 Mpa

c) Total Stress

Total Stress = Edge Load Stress + Edge Temperature Stress

= 6.15 Mpa

This value is greater than the allowable flexural strength 4.6 Mpa

So, Slab thickness 150 mm assumed is inadequate.

Trial 2Let Thickness of road be h : 200 mm

l = radius of relative Stiffness = 4 Sqrt {(E * h^3) / (12*(1 - ^2 )*K) }

42.000))

835.44 mm

a) Edge Load Stress :Wheel Load = 51.00KN k = 42.00 x10^-3 N/sqmm/mm.

Pavement thickness = 200mm

From The Graph Edge load Stress (Fig 2 of SP62:2004) = 2.75 Mpa

b) Edge temparature Stress

For the state of Andhra Pradesh the temperature differentials ( Dt ) for 200mm thick slab is 17.3 oC

Alpha = Coefficient of Thermal expansion of Concrete = 10 X Power(10, -6)

(As per Clause 3.8 , page 8 of SP62:2004 )

L / l = : 4.489

W / l = : 4.489

FOR L / l = 4.489

Bradbury's coefficient C from Fig. 1, (Page 9,SP 62:2004)

By interpolation C value may be arriaved = (0.44+(0.72-0.44)*(4.489-4)/(5-4))

= 0.577

From The Graph Edge Temperature Stress (Fig 1, page 9 of SP62:2004) = 1.50 Mpa

3750 / 673.31

=4 th Sqrt( (3*10^4*200^3)/(12*(1-0.15^2)*

3750 / 835.44

3750 / 835.44

3750 / 673.31


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c) Total Stress

Total Stress = Edge Load Stress + Edge Temperature Stress

= 4.25 Mpa

This value is less than the allowable flexural strength 4.6 Mpa

So, Slab thickness 200 mm assumed is adequate.

2 Corner Load Stress

Wheel Load = 51.00KN k = 42.00 x10^-3 N/sqmm/mm.Pavement thickness = 200mm

From The Graph Corner Load Stress (Fig 3 of SP62:2004) = 3.00 Mpa

This value is less than the allowable flexural strength 4.6 Mpa

So, Slab thickness 200 mm assumed is adequate.

DESIGN OF JOINTS

Spacing of Contraction Joint (Lc) :

Sc = Allowable stresses in tension during initial period of curing = 0.8kg/Sqcm.

f = Coefficient of friction at interface = 1.4

W = Unit weight of cement concrete = 2400 kg/Cum.

Lc = 4.76 m

IRC specifies maximum spacing of 4.50m the design value is 3.75m (


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Table - 1

SoakedCBR% 2 3 4 5 7 10 15 20 50

K Valuex10^-3N/mm2/mm 21 28 35 42 48 55 62 69 140

Table - 2

Expected Values of standard Deviation of Compressive Strength

Grade of Concrete Standard Deviation for different degrees of control, Mpa

Tab le - 3 Tab l e - 4

Recommended Temperature Differentials for Concrete Slabs

L / I and W / I C1 0.000 15 20 25

2 0.040 III A.P. 17.3 19.0 20.33 0.1754 0.4405 0.7206 0.9207 1.030 Mix Mix type8 1.075 20 1.2.49 1.080 30 1.1.5.3

10 1.07511 1.050

12and above 1.000

Temperature Differentials, C inSlabs of thickness in cms

Zone States

6.3

6.6

7.3

7.65.6

Approximate K Value corresponding to C.B.R. values

Very good Good Fair

7.0

Values of co-efficient 'C' based on Bradbury's

Chart

M 30

M 35

M 40

6.0

5.3

5.0


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A B C D E F G H I J K L M N O P Q R S T U V W Xa b c d e f g h i j k l m n o p q r s t u v w xA B C D E F G H I J K L M N O P Q R S T U V W X

a b d e f g h k lm o p q r s v w


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Y Zy zY Z

y z

cc pavement (revised design)

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