Pavement Design

2. PAVEMENT DESIGN
AND ANALYSIS
(CE-860)
LEC-02
Fall Semester 2017
Dr. Arshad Hussain
arshad_nit@yahoo.com , Office Room#111, Tel:
05190854163, Cell: 03419756251
National Institute of Transportation (NIT)
School of Civil & Environmental Engineering (SCEE)
National University of Science and Technology (NUST)
NUST Campus, Sector H-12, Islamabad

3. PAVEMENT TYPES
 Flexible Pavements
 Rigid Pavements

4. FLEXIBLE PAVEMENT
 Based on Structural Response flexible
pavements normally use asphaltic
concrete (AC) as the surface, and
sometimes underlying layers.
 Flexible pavements are made of a
series of layers with the strongest
material layers at or near the surface.

5. FLEXIBLE PAVEMENT
 The load-carrying capacity of flexible
pavements is brought about by the
load-distributing characteristics of the
layered system, thereby, distributing
the load over the subgrade, rather
than by the bending action of the slab.

6. FLEXIBLE PAVEMENT
 Structure
◦ Surface course
◦ Base course
◦ Subbase course
◦ Subgrade

7. COMPONENTS OF FLEXIBLE
PAVEMENT
 Seal Coat
 Surface Course
 Binder Course
 Base Course
 Subbase Course
 Compacted Subgrade
 Natural Subgrade

9. RIGID PAVEMENT
 Rigid pavements are made up of Portland
Cement Concrete and may or may not have a
base course between the pavement and the
subgrade.
 The rigid pavement, because of its rigidity and
high modulus of elasticity, tends to distribute
the load over a relatively wide area of soil;
thus, a major portion of the structure capacity
is supplied by the slab itself.

10. RIGID PAVEMENT
 The major factor considered for the
design of rigid pavements is the
structural strength of concrete. Minor
variations in the subgrade strength
have little influence on the structural
Capacity of Concrete Pavements.

11. RIGID PAVEMENT
Base course are provided under rigid
pavements for various reasons:
 Control of Pumping
 Control of Frost Action
 Drainage
 Control of Shrinkage & Swell potential
of the subgrade
 Construction facilitation

13. RIGID PAVEMENT
 Provision of Base/Subbase Course lends
some structural capacity to the pavement.
However, its contribution to the load carrying
capacity may be relatively minor.
 Load Carrying Capacity of rigid pavements is
due to BENDING of slabs.

14. RIGID PAVEMENT
 Structure
◦ Surface course
◦ Base course
◦ Subbase course
◦ Subgrade

15. COMPONENTS OF RIGID
PAVEMENT
 PCC Slab
 Granular Base/Subbase Layer
 Subgrade

16. HIGHWAY AND AIRFIELD PAVEMENTS
 Highways are generally 24 feet wide
 Runways are 150 feet wide
 Taxiways 75 feet wide
 Runways are always crowned, whereas,
highways may or may not.
 Taxiways and runway ends are constructed
using thicker section than the central portion,
due to high concentration of traffic.

17. HIGHWAY AND AIRFIELD PAVEMENTS
 Rigid Highways, if without
base/subbase layer, due to heavy
distresses always show pumping.
 Airfield pavements comparatively
show less pumping.
 Highways; more distresses at the
edge of the pavement.
 Airfield pavements do not show edge
distresses.

18. HIGHWAY AND AIRFIELD PAVEMENTS
 Major differences are repetition of load,
distribution of traffic and geometry of
pavement.
 For a given wheel load and tire
pressure, Highway Pavements are
thicker than Airfield Pavements. Due to
high repetition of load on highway
pavements and due to close application
to the edges.

19. HIGHWAY AND AIRFIELD PAVEMENTS
 However, as the gross weight of
aircraft is very high with the result that
airfield pavements are actually thicker
in practice.

20. FRAMEWORK OF PAVEMENT DESIGN
TYPES OF FAILURES
 Structural Failure
 Functional Failure

21. STRUCTURAL FAILURE
 Collapse or a breakdown of one or
more of the pavement components of
such magnitude to make the pavement
incapable of sustaining loads imposed
on the surface.

22. FUNCTIONAL FAILURE
 May or may not include structural
failure, however, the pavement will not
carry out its intended function without
causing distress and discomfort to
passengers or high stresses to the
vehicle due to surface roughness.

23. CAUSES OF DISTRESS
 Overloading
 High load repetitions
 High tire pressure
 Climatic and environmental
conditions
 Freeze-Thaw or Dry-Wet

24. SERVICEABILITY
 Serviceability is used to describe how “GOOD”
a pavement is.
 Developed during AASHTO Road Tests.
 Present Serviceability Index (PSI)
 Used as a measure of serviceability.
 Rating scale 0 to 5.
 PSI = 5 – Perfect pavement
 PSI = 0 – Imperfect pavement
 Done by a panel of individuals.
 Based on objective measurements made on
pavement surface.

25. SERVICEABILITY
 Longitudinal Roughness.
 Amount of Cracking and Patching.
 Rut Depth for Flexible Pavements.

26. PSI EQUATION
 For Flexible Pavement
PSI = 5.03 - 1.9 log(1+SV) -
0.01√(C+P) – 1.38(RD)²
 For Rigid Pavement
PSI = 5.41-1.8 log(1+SV)-0.09√(C+P)

27. ABBREVIATIONS
 PSI – Pavement serviceability index
 C – Linear feet of cracking per 1000 sq
feet area
 P – Bituminous patching in sq ft / 1000
sq ft area
 SV – Slope Variance
 RD – Rut Depth in inches (both wheel
tracks) measured with 4 feet straight
edge

28. AGENCY ABBREVIATIONS
 AASHTO – American Association of State
Highway and Transportation Officials
 FAA – Federal Aviation Administration
 AI – Asphalt Institute
 TRL – Transportation Research Laboratory
 ARRB – Australian Road Research Board
 FHWA – Federal Highway Administration

29. AGENCY ABBREVIATIONS
 NCHRP – National Cooperative
Highway Research Program
 TRB – Transportation Research Board
 NHA – National Highway Authority
 NTRC – National Transportation
Research Centre
 ASTM – American Standards for Testing
Materials
 BSS – British Standard Specifications
 ACI – American Concrete Institute

30. Thanks