This ppt is essential for civil students

1. SUBMITTED BY :
Moses Payma Dukuly
B.TECH 2nd
YEAR
CIVIL BRANCH
ROLL: E16402

3. CONTENT
INTRODUCTION
TYPES OF PAVEMENTS
(a) Flexible pavements
(b) Rigid pavements
© Semi rigid pavements
 Design factors
 Reqirement of good pavement
California bearing ratio (CBR)

4. Introduction
Pavement design is the major component in the road
construction.
Nearly one-third or one-half of the total cost of
construction , so careful consideration should be taken in
design of pavement.
For the better road condition ,good pavement is used
can easily bear the load as well easily transmit the load.
Flexible pavement has shorter life span as compared
to rigid pavements.

5. Type of pavements
FLEXIBLE PAVEMENT
RIGID PAVEMENT
SEMI-RIGID PAVEMENT

6. Flexible Pavements
Flexible pavemants are those pavements which are
f lexible under the action of load.
Bituminous is one of the best flexible pavement
material.
Flexible pavement transmit the vertical stress to the
lower layers.
Flexible pavement is form in layers , so first layer is
form strong as compared to other.
It consist of 4 parts soil subgrade, subbase ,base course
,surface course.

7. Flexible Pavement
 Structure
 Surface course
 Base course
 Subbase course
 Subgrade

8. Design parameters for Flexible Pavements
1.VDF(Visual display factor)
It is a multiplier which converts the number of
commericial vechiles of different axle loads and axle
configuration to the number of standard load
repetitions.
2. SUB GRADE:
 IT Should be well compacted in cutting as well as filling .
 Strength is assesed in terms of CBR value.

9. 3. Traffic
 As per the IRC:37 design traffic should be 0.1 msa to
2 msa (million standard axles).
 Weight of commercial vehicle (laden) is
considered as 3 tonnes or more.
 For design traffic we consider the existing traffic and
rate of growth.

10. 4. Design life
 The no. of years to be taken until the major
reconstruction.
 Design life depend upon the environmental conditions,
materials used ,maintenance etc.
 For rural roads design life of 10 years is considered.
 In low volume roads for the thin bituminous surfacing
design life of 5 years is considered.

11. Flexible Pavement – Construction

12. Rigid Pavements
Rigid pavements are those pavements whose surface is
hard
This pavement can not transferd the load from ground
surface to lower suface.
Rigid Pavement has the capacity to transfer the wheel
load from wider area of roads.
Rigid pavement is formed either of opc slabs or cement
conrete .

13. Rigid Pavement
 Structure
 Surface course
 Base course
 Subbase course
 Subgrade

15. Design Parameters for rigid pavement
1. Wheel load stresses :
Westergaard developed relationships for the stress at interior, edge and
corner regions, denoted as i; e; c in kg/cm2.

16. 2. Temperature Stress :
Temperature stresses are developed in cement concrete
pavement due to variation in slab temperature.
This is caused by
(A) daily variation resulting in a temperature
gradient across the thickness of the slab and
(B) seasonal variation resulting in overall change in
the slab temperature.
The former results in warping stresses and the later in
Frictional stresses.

17. Design of joints
1. EXPANSION JOINTS :
The purpose of the expansion joint is to allow the
expansion of the pavement due to rise in temperature
with respect to construction temperature.
 The design consideration are:
 Provided along the longitudinal direction,
 design involves ending the joint spacing for a given
expansion joint thickness (say 2.5 cm specied by IRC)
subjected to some maximum spacing.

18. 2. Contraction joints
 The purpose of the contaction joint is to allow the
contraction of the slab due to fall in slab temperature below
the construction temperature.
 The design considerations are:
 The movement is restricted by the sub-grade friction
 Design involves the length of the slab given by:
Lc =2* 10^4 Sc/W:f
Where,
 where, Sc is the allowable stress in tension in cement
concrete and is taken as 0.8 kg/cm2, W is the unit weight of
the concrete which can be taken as 2400 kg/cm3 and
 f is the coecient of sub-grade friction which can be taken as
1.5.

19. Computation of design traffic
a=p(1+r)^(n+x)
Where,
a= no. of commercial vechiles per day for design
p= no. of commercial vechiles per day last count
r=annual growth rate of commercial traffic
n=no. of years between last count and year of
completion of construction

20. Selection Factors Of Pavement
 Initial cost
 Availability of good materials
 Cost of maintenance
 Environmental conditions
 Availability of industrial wastes
 Traffic intensity
 Ease of labour
 Favourable working conditions

21. Requirement Of Good Pavement
It should be Economical.
It should be cheap and durable.
Ease to construct.
Good surface finish.
Easily visible marks on the pavements.
It should have low maintenance cost.
It should provide good visibility in night.

22. CALIFORNIA BEARING
RATIO
 Conduct on sample which remoulded at OMC and
dry density.
 Test should be done per km depend on soil
type.
 If CBR less than 2% for 100 mm thickness then
minimum CBR of 10% is to be provided to the sub-
base for CBR of 2%.
 If CBR more than 15% , no need to provide sub-
base.