1) The document summarizes the design and construction of flexible pavements. It describes the typical layers of a flexible pavement from top to bottom including the surface course, binder course, base course, sub-base course, and subgrade. 2) It also discusses factors involved in the design of flexible pavements like traffic load, subgrade soil properties, climate, and required material properties. Common failure modes of flexible pavements include alligator cracking, rutting, and reflection cracking. 3) Design life, traffic calculations, and common tests for bitumen are also outlined. The advantages of flexible pavements include adaptability and ease of repair while the disadvantages include higher maintenance costs and shorter life under heavy traffic loads

1. Seminar
on
DESIGN &CONSTRUCTION OF FLEXIBLE PAVEMENT
DEPARMENT OF CIVIL ENGINEERING
Under The Guidance of Submitted by
MR.SHUBHAJITDEY SUSMITAMAITY
ROLL NO – 33201316022
B.TECH ,3rd yr,6th sem

2. outline
Pavement purpose
Types of pavement
Layers of pavement
Flexible pavement
Typical layers of flexible pavement
Seal coat
Tack coat
Prime coat
Surface course
Binder course
Base &sub base course
Load distribution
Basic principle
Factors for design pavement
Failure for flexible pavement
Design life
Pavement thickness
Test of bitumen
Advantages & dis advantages of flexible pavement

3. Pavement purpose
• Load support
• Smoothness
• Drainage
Road in 1919 – from DC to Richmond the Asphalt
Institute

4. Types of pavement
Flexible pavement Rigid pavement

5. Layer of pavement

6. Flexible pavement
• Flexible Pavement
• Hot mix asphalt (HMA) pavements
• Called "flexible" since the total pavement structure bends (or flexes)
to accommodate traffic loads
• About 82.2% of paved U.S. roads use flexible pavement
• About 95.7% of paved U.S. roads are surfaced with HMA

7. Typical Layers in flexible
pavement from top
1.Seal coat
2.Surface course
3.Tack coat
4.Binder course
5.Prime coat
6.Base course
7.Sub-base course
8.Natural subgrade
9.Compacted subgrade

9. SUB-GRADE
The soil sub grade is a layer of natural
or selected soil rom identified borow
pits fulfilling the specified
requirements & well compacted in
layers to the desire density .
It is the lowest layer of the pavement

10. SUB-BASE
COURSE
The sub-base course is the layer of
material beneath the base course.
The primary functions are to
provide structural support,
improve drainage, and reduce the
intrusion of fines from the sub-
grade in the pavement structure

11. BASE COURSE
The base course is the layer of
material immediately beneath the
surface of binder course .
it provides additional load
distribution and contributes to the
sub-surface drainage.
It may be composed of crushed
stone, crushed slag, and other
untreated or stabilized materials.

12. PRIME COAT
Prime coat is an application of low
viscous cutback bitumen to an
absorbent surface like granular
bases on which binder layer is
placed.
It provides bonding between two
layers. Unlike tack coat, prime coat
penetrates into the layer below,
plugs the voids, and forms a
watertight surface

13. SURFACE
COURSE
Surface course is the layer directly in contact
with traffic loads and generally contains
superior quality materials.
a. It provides friction, smoothness, drainage,
b. It must be tough to resist the distortion
under traffic and provide a smooth and skid-
resistant riding surface,
c. It must be waterproof .

14. TACK COAT
Tack coat is a very light application
of asphalt, usually asphalt
emulsion diluted with water.
It provides proper bonding
between two layer of binder
course and must be thin, uniformly
cover the entire surface, and set
very fast

15. Seal coat
Thin asphalt surface treatment used to—
1.waterproof or seal the surface
2.no non-skid slippery surface
3.improve night visibility
4.revaitalize old bituminous wearing surface

16. BINDER COURSE
• This layer provides the bulk of the
asphalt concrete structure.

17. TYPES OF FLEXIBLE
PAVEMENT
Dense grade
Open grade
Gap grade

18. Load distribution

19. BASIC PRINCIPLE
IRC (37-2012)
• Vertical stress or
strain on sub-grade
• Tensile stress or
strain on surface
course

20. FACTOR FOR
DESIGN OF
PAVEMENT
Design wheel load
• Static load on wheels
• Contact Pressure
• Load Repetition
Subgrade soil
• Thickness of pavement required
• Stress- strain behaviour under load
• Moisture variation
Climatic factors
Pavement component materials
Environment factors
Traffic Characteristics
Required Cross sectional elements of the alignment

21. FAILURES
OF
FLEXIBLE
PAVEMENTS
. Alligator
cracking or Map
cracking (Fatigue)
Consolidation of
pavement layers
(Rutting)
Shear failure
cracking
Longitudinal
cracking
Frost heaving
Lack of binding to
the lower course
Reflection
cracking
Formation of
waves and
corrugation
Bleeding
Pumping

22. DESIGN LIFE
National Highways – 15
Years
Expressways and Urban
Roads – 20 Years
Other Category Roads –
10 – 15 Years

23. COMPUTATION OF TRAFFIC FOR USE
OF PAVEMENT THICKNESS DESIGN
CHART
365 xA[(1+r)n – 1]
N = --------------------------- x D x F
r
N = Cumulative No. of standard axles to be catered for the
design in terms of msa
D = Lane distribution factor
A = Initial traffic, in the year of completion of construction,
in terms of number of commercial vehicles per day
F = Vehicle Damage Factor
n = Design life in years
r = Annual growth rate of commercial vehicles

24. TESTS OF
BITUMEN
Ductility test
Flash and Fire point test
Float test
Loss on heating test
Penetration test
Softening point test
Specific gravity test
Viscosity test
Water content test

25. THE
ADVANTAGES
OF FLEXIBLE
PAVEMENTS
» Adaptability to stage construction
» Availability of low-cost types that can be
easily built
» Ability to be easily opened and patched
» Easy to repair frost heave and settlement
» Resistance to the formation of ice glaze

26. The
disadvantages
» Higher maintenance costs
» Shorter life span under heavy
use
» Damage by oils and certain
chemicals
» Weak edges that may require
curbs or edge devices

27. references
2. IS: 20:2007 Codes for the rural roads & standard designing of a pavement.
• 3. Khanna & Justo, Highway Engineering Provisions & general data obtained for soil
tests, designing of flexible pavement & traffic survey study.
• 4. B.N Dutta, Cost Estimation, Estimation procedures & format obtained by this book.
• 5. K R Arora, Soil Mechanics & Foundation Engineering Soil tests & their details are
obtained.
• 6. B.C Punmia, Soil Mechanics, Soil tests & their applications are preferred from this
book.
• 7. www.wikipedia.org
• 8. www.civil.org
• 9. www.civilworks.org
• 10. www.nptel.co.in

28. THANK YOU