This document discusses different types of pavements, including flexible, rigid, and semi-rigid pavements. It describes key design factors for both flexible and rigid pavements such as traffic load, pavement materials, subgrade strength assessed by CBR value, and design life. The document emphasizes the importance of pavement design, noting it accounts for nearly half the road construction cost. Good pavements are important as they can easily bear and transmit loads.

1. SUBMITTED BY :
GARVIT GOYAL
B.TECH 4TH YEAR
CIVIL BRANCH

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 eaisly bear the load as well eaisly 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
flexible 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 is 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 nding 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 Pavements
 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.
Eaisly 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.