1
Transportation Engineering II
The Pavement
2
What is a Pavement?
• A multi layer system that distributes
the vehicular loads over a larger area
3
What is a Pavement?
OR
• Highway pavement is a structure
consisting of superimposed layers of
selected and processed mat...
4
What is a Pavement?
• Pavement is the upper part of roadway,
airport or parking area structure
• It includes all layers ...
5
Functions of the Pavement
• Reduce and distribute the traffic loading so as not
to damage the subgrade
• – Provide vehic...
6
Requirements of pavement structure
• Sufficient thickness to spread loading to a pressure
intensity tolerable by subgade...
7
Classification of Pavements
8
Flexible Pavements
PAVEMENTS
Rigid Pavements
Types of Pavement
9
Natural Soil (Subgrade)
Aggregate Subbase Course
Aggregate Base CourseAsphalt Concrete
Flexible Pavements
10
Given Wheel Load
Load Distribution in Flexible Pavements
Flexible Pavements
150 psi
3 psi
Wearing C.
Base
Sub-base
Sub-...
11
Rigid Pavements
12
Rigid Pavements
Load Distribution in Rigid Pavements
13
Pavements Comparison
Flexible pavements:
• Deep foundations / multi layer construction
• Energy consumption due to tran...
14
Pavements Comparison
• Heavy vehicles consume less fuel on rigid
pavements
• Rigid pavements more economic when
conside...
15
Flexible Pavement
• “A flexible pavement is a structure that
maintains intimate contact with and distributes
load to th...
16
OR
• It is a structure which distributes the traffic
loading stresses to the soil (sub grade) at a
magnitude that will ...
17
Flexible Pavement
Flexible pavements
• Elastic
• Three main layers
– Surfacing
• Wearing course
• Base course
– Road ba...
18
Flexible Pavement
• Flexible pavements are so named
because the total pavement structure
deflects, or flexes, under loa...
19
Flexible Pavement
• Each layer receives the loads from
the above layer, spreads them out,
then passes on these loads to...
20
Load Distribution In Flexible Pavements
21
Structure of Flexible Pavement
• In order to take maximum advantage of
this property, material layers are usually
arran...
22
– Surface Course: This is the top layer and the layer
that comes in contact with traffic.
– Base Course: This is the la...
23
– Sub-grade Course: The "sub-grade" is the
material upon which the pavement structure is
placed. Although there is a te...
24
Surface Course
• The surface course is the layer in contact
with traffic loads and normally contains the
highest qualit...
25
• In addition, it serves to prevent the entrance
of excessive quantities of surface water into
the underlying base, sub...
26
Wearing Course
• This is the layer in direct contact with traffic
loads. It is meant to take the brunt of
traffic wear ...
27
– Intermediate/Binder Course: This layer
provides the bulk of the HMA structure.
It's main purpose is to distribute loa...
28
Base Course
• The base course is immediately beneath
the surface course. It provides additional
load distribution and c...
29
– HMA: In certain situations where high
base stiffness is desired, base courses
can be constructed using a variety of
H...
30
Lime rock Base Course Undergoing Final Grading
31
Sub-base Course
• The sub-base course is between the base
course and the sub-grade. It functions
primarily as structura...
32
Sub-base Course
• The sub-base generally consists of lower
quality materials than the base course but
better than the s...
33
• However, a pavement constructed over a
low quality soil such as a swelling clay may
require the additional load distr...
34
Sub-grade
• Although a pavement's wearing course
is most prominent, the success or failure
of a pavement is more often ...
35
• Sub-grades be composed of a wide
range of materials although some are
much better than others. This
subsection discus...
36
Sub-grade Preparation Sub-grade Failure Crack
37
Types of Flexible Pavement
Dense-graded
Open-graded Gap-graded
38
Flexible Pavement – Construction
39
Types of Pavements
40
Types of Pavements
41
Types of Pavements
42
Types of Pavements
43
Types of Pavements
44
Types of Pavements
45
Types of Flexible Pavements
46
Types of Flexible Pavements
47
Types of Flexible Pavements
48
Wheel Load
Sub-grade
Bituminous Layer
Typical Load Distribution in Flexible Pavement
49
Vertical stress
Foundation stress
Typical Stress Distribution in Flexible Pavement.
50
Load Transfer Mechanism
51
Load Transfer Mechanism
52
Rigid Pavement
• Rigid pavements are those, which contain
sufficient beam strength to be able to bridge
over the locali...
53
Rigid Pavement
• Rigidity – does not deform under stress
• Concrete – air entrained increases resistance
to frost damag...
54
Rigid Pavements
55
Basic Components of Concrete Pavement
56
Concrete paver
57
Rigid Pavements
Load Distribution in Rigid Pavements
58
Rigid Pavements
• Rigid pavements are so named because
the pavement structure deflects very little
under loading due to...
59
• Because of its relative rigidity, the
pavement structure distributes loads over
a wide area with only one, or at most...
60
Structure of Rigid Pavement
– Surface course. This is the top layer, which
consists of the PCC slab, reinforced or
cont...
61
Surface Course
• The surface course is the layer in contact with
traffic loads and is made of PCC or RCC. It
provides c...
62
PCC Surface
Rigid Pavement Slab
(Surface Course) Thickness
63
Base Course
• The base course is immediately beneath the
surface course. It provides
• Additional load distribution,
• ...
64
– Stabilized aggregate or soil. Stabilizing agents
are used to bind otherwise loose particles to
one another, providing...
65
– Lean concrete. Contains less Portland cement
paste than a typical PCC and is stronger than a
stabilized aggregates. L...
66
Completed CTB with Curing Seal Lean Concrete Base Material
67
Sub-base Course
• The sub-base course is the portion of the pavement
structure between the base course and the sub-
gra...
68
• Sub grade provides support to the
overlying concrete slab. If it is of good
quality then slab can be laid over it wit...
69
Types of Rigid Pavement
• Jointed Plain Concrete Pavement
(JPCP)
70
Types of Rigid Pavement
• Continuously Reinforced Concrete
Pavement (CRCP)
Photo from the Concrete Reinforcing Steel In...
71
Rigid Pavement –
Construction
Slipform
Fixed form
72
Pavements Comparison
Flexible pavements:
• Deep foundations / multi layer construction
• Energy consumption due to tran...
73
Pavements Comparison
74
Types of Pavement Failure
• Failure criteria
• Flexible Pavements
• Fatigue Cracking,
• Rutting,
• Thermal Cracking,
• ...
75
Flexible vrs. Rigid Pavements
76
Flexible vrs. Rigid Pavements
77
Airport-Highway Pavements
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Lecture#01

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  • Heavy vehicles cause greater deflection on flexible pavements rather than on rigid pavements. When the pavement deflects or moves, it absorbs a portion of the vehicle energy that otherwise would be available to propel the vehicle forward.
    Concrete’s rigid design reduces the pavement’s deflection and corresponding fuel consumption. Also smoothness of concrete pavements is less affected by seasonal changes, which could also contribute to lower fuel consumption.
  • Heavy vehicles cause greater deflection on flexible pavements rather than on rigid pavements. When the pavement deflects or moves, it absorbs a portion of the vehicle energy that otherwise would be available to propel the vehicle forward.
    Concrete’s rigid design reduces the pavement’s deflection and corresponding fuel consumption. Also smoothness of concrete pavements is less affected by seasonal changes, which could also contribute to lower fuel consumption.
  • More in pavement guide interactive
    Stevens Way will be fixed form starting in May
  • Heavy vehicles cause greater deflection on flexible pavements rather than on rigid pavements. When the pavement deflects or moves, it absorbs a portion of the vehicle energy that otherwise would be available to propel the vehicle forward.
    Concrete’s rigid design reduces the pavement’s deflection and corresponding fuel consumption. Also smoothness of concrete pavements is less affected by seasonal changes, which could also contribute to lower fuel consumption.
  • Lecture#01

    1. 1. 1 Transportation Engineering II The Pavement
    2. 2. 2 What is a Pavement? • A multi layer system that distributes the vehicular loads over a larger area
    3. 3. 3 What is a Pavement? OR • Highway pavement is a structure consisting of superimposed layers of selected and processed materials whose primary function is to distribute the applied vehicle load to the sub grade. OR • It can also be defined as “structure which separates the tires of vehicles from the under lying foundation.”
    4. 4. 4 What is a Pavement? • Pavement is the upper part of roadway, airport or parking area structure • It includes all layers resting on the original ground • – It consists of all structural elements or layers, including shoulders
    5. 5. 5 Functions of the Pavement • Reduce and distribute the traffic loading so as not to damage the subgrade • – Provide vehicle access between two points under all-weather conditions • – Provide safe, smooth and comfortable ride to road users without undue delays and excessive wear & tear • – Meet environmental and aesthetics requirement • – Limited noise and air pollution • – Reasonable economy
    6. 6. 6 Requirements of pavement structure • Sufficient thickness to spread loading to a pressure intensity tolerable by subgade • Sufficiently strong to carry imposed stress due to traffic load • Sufficient thickness to prevent the effect of frost susceptible subgrade • Pavement material should be impervious to penetration of surface water which could weaken subgrade and subsequently pavement • Pavement mat. shd be non-frost susceptible • Pavement surface shd. be skid resistant
    7. 7. 7 Classification of Pavements
    8. 8. 8 Flexible Pavements PAVEMENTS Rigid Pavements Types of Pavement
    9. 9. 9 Natural Soil (Subgrade) Aggregate Subbase Course Aggregate Base CourseAsphalt Concrete Flexible Pavements
    10. 10. 10 Given Wheel Load Load Distribution in Flexible Pavements Flexible Pavements 150 psi 3 psi Wearing C. Base Sub-base Sub-grade
    11. 11. 11 Rigid Pavements
    12. 12. 12 Rigid Pavements Load Distribution in Rigid Pavements
    13. 13. 13 Pavements Comparison Flexible pavements: • Deep foundations / multi layer construction • Energy consumption due to transportation of materials • Increasing cost of asphalt due to high oil prices Rigid pavements • Single layer • Generally last longer • May require asphalt topping due to noise / comfort issues
    14. 14. 14 Pavements Comparison • Heavy vehicles consume less fuel on rigid pavements • Rigid pavements more economic when considering environmental / life-cycle costing
    15. 15. 15 Flexible Pavement • “A flexible pavement is a structure that maintains intimate contact with and distributes load to the sub grade and depends on aggregate interlock, particle friction and cohesion for stability”
    16. 16. 16 OR • It is a structure which distributes the traffic loading stresses to the soil (sub grade) at a magnitude that will not shear or distort the soil i.e., from 150 psi to 3 psi OR • Pavement which reflects deformation of sub grade & the subsequent layers on to the surface” i.e.; load is transmitted from grain to grain through contact points of granular material, i.e. in a compressive way. FlexiblePavement
    17. 17. 17 Flexible Pavement Flexible pavements • Elastic • Three main layers – Surfacing • Wearing course • Base course – Road base – Sub base • Supported by Sub-grade
    18. 18. 18 Flexible Pavement • Flexible pavements are so named because the total pavement structure deflects, or flexes, under loading. A flexible pavement structure is typically composed of several layers of different materials. Introduction
    19. 19. 19 Flexible Pavement • Each layer receives the loads from the above layer, spreads them out, then passes on these loads to the next layer below. Thus, the further down in the pavement structure a particular layer is, the less load (in terms of force per unit area) it must carry.
    20. 20. 20 Load Distribution In Flexible Pavements
    21. 21. 21 Structure of Flexible Pavement • In order to take maximum advantage of this property, material layers are usually arranged in order of descending load bearing capacity with the highest load bearing capacity material (and most expensive) on the top and the lowest load bearing capacity material (and least expensive) at the bottom.
    22. 22. 22 – Surface Course: This is the top layer and the layer that comes in contact with traffic. – Base Course: This is the layer directly below the surface course and generally consists of aggregates (either stabilized or un-stabilized). – Sub-base Course: This is the layer (or layers) under the base layer. A sub-base is not always needed. Structure of Flexible Pavement
    23. 23. 23 – Sub-grade Course: The "sub-grade" is the material upon which the pavement structure is placed. Although there is a tendency to look at pavement performance in terms of pavement structure and mix design alone. The sub-grade can often be the overriding factor in pavement performance. Structure of Flexible Pavement
    24. 24. 24 Surface Course • The surface course is the layer in contact with traffic loads and normally contains the highest quality materials. It provides characteristics such as friction, smoothness, noise control, rut and shoving resistance and drainage.
    25. 25. 25 • In addition, it serves to prevent the entrance of excessive quantities of surface water into the underlying base, sub-base and sub- grade. This top structural layer of material is sometimes subdivided into two layers. Surface Course
    26. 26. 26 Wearing Course • This is the layer in direct contact with traffic loads. It is meant to take the brunt of traffic wear and can be removed and replaced as it becomes worn. A properly designed (and funded) preservation program should be able to identify pavement surface distress while it is still confined to the wearing course. This way, the wearing course can be rehabilitated before distress propagates into the underlying intermediate/blinder course
    27. 27. 27 – Intermediate/Binder Course: This layer provides the bulk of the HMA structure. It's main purpose is to distribute load. Intermediate/Binder Course
    28. 28. 28 Base Course • The base course is immediately beneath the surface course. It provides additional load distribution and contributes to drainage and frost resistance. Base courses are usually constructed out of: – Aggregates: Base courses are most typically constructed from durable aggregates that will not be damaged by moisture or frost action. Aggregates can be either stabilized or un- stabilized.
    29. 29. 29 – HMA: In certain situations where high base stiffness is desired, base courses can be constructed using a variety of HMA mixes. In relation to surface course HMA mixes, base course mixes usually contain larger maximum aggregate sizes, are more open graded and are subject to more lenient specifications.
    30. 30. 30 Lime rock Base Course Undergoing Final Grading
    31. 31. 31 Sub-base Course • The sub-base course is between the base course and the sub-grade. It functions primarily as structural support but it can also: – Minimize the intrusion of fines from the sub- grade into the pavement structure. – Improves drainage. – Minimize frost action damage. – Provides a working platform for construction.
    32. 32. 32 Sub-base Course • The sub-base generally consists of lower quality materials than the base course but better than the sub-grade soils. • A sub-base course is not always needed or used. • For example, a pavement constructed over a high quality, stiff sub-grade may not need the additional features offered by a sub-base course so it may be omitted from design.
    33. 33. 33 • However, a pavement constructed over a low quality soil such as a swelling clay may require the additional load distribution characteristic that a sub-base course can offer. In this scenario the sub-base course may consist of high quality fill used to replace poor quality sub-grade.
    34. 34. 34 Sub-grade • Although a pavement's wearing course is most prominent, the success or failure of a pavement is more often than not dependent upon the underlying sub- grade , the material upon which the pavement structure is built.
    35. 35. 35 • Sub-grades be composed of a wide range of materials although some are much better than others. This subsection discusses a few of the aspects of sub-grade materials that make them either desirable or undesirable and the typical tests used to characterize sub-grades. Sub-grade
    36. 36. 36 Sub-grade Preparation Sub-grade Failure Crack
    37. 37. 37 Types of Flexible Pavement Dense-graded Open-graded Gap-graded
    38. 38. 38 Flexible Pavement – Construction
    39. 39. 39 Types of Pavements
    40. 40. 40 Types of Pavements
    41. 41. 41 Types of Pavements
    42. 42. 42 Types of Pavements
    43. 43. 43 Types of Pavements
    44. 44. 44 Types of Pavements
    45. 45. 45 Types of Flexible Pavements
    46. 46. 46 Types of Flexible Pavements
    47. 47. 47 Types of Flexible Pavements
    48. 48. 48 Wheel Load Sub-grade Bituminous Layer Typical Load Distribution in Flexible Pavement
    49. 49. 49 Vertical stress Foundation stress Typical Stress Distribution in Flexible Pavement.
    50. 50. 50 Load Transfer Mechanism
    51. 51. 51 Load Transfer Mechanism
    52. 52. 52 Rigid Pavement • Rigid pavements are those, which contain sufficient beam strength to be able to bridge over the localized sub-grade failures and areas of in adequate support. OR • Load is transmitted through beam action of slab in rigid pavements. OR • Rigid pavements are those, which reduces the stress concentration and distributes the reduced stresses uniformly to the area under the slab.
    53. 53. 53 Rigid Pavement • Rigidity – does not deform under stress • Concrete – air entrained increases resistance to frost damage and de-icing salt corrosion • Reinforcement – may be bars or mesh. Continuous rigid pavements have heavy reinforcement • Joints – used in non-continuous pavements to allow for thermal movement. Includes a ‘filler’ and surface sealant • Rigid pavements – laid as single layer by ‘concrete paver’
    54. 54. 54 Rigid Pavements
    55. 55. 55 Basic Components of Concrete Pavement
    56. 56. 56 Concrete paver
    57. 57. 57 Rigid Pavements Load Distribution in Rigid Pavements
    58. 58. 58 Rigid Pavements • Rigid pavements are so named because the pavement structure deflects very little under loading due to the high modulus of elasticity of their surface course. A rigid pavement structure is typically composed of a PCC surface course built on top of either – the sub-grade or – an underlying base course. Introduction
    59. 59. 59 • Because of its relative rigidity, the pavement structure distributes loads over a wide area with only one, or at most two, structural layers. • There are other types of surfaces also i.e.; reinforced, continuously reinforced etc. Rigid Pavements
    60. 60. 60 Structure of Rigid Pavement – Surface course. This is the top layer, which consists of the PCC slab, reinforced or continuously reinforced slabs . – Base course. This is the layer directly below the PCC layer and generally consists of aggregate or stabilized sub-grade. – Sub-base course. This is the layer (or layers) under the base layer. A sub-base is not always needed and therefore may often be omitted.
    61. 61. 61 Surface Course • The surface course is the layer in contact with traffic loads and is made of PCC or RCC. It provides characteristics such as friction, smoothness, noise control and drainage. In addition, it serves as a waterproofing layer to the underlying base, sub-base and sub-grade. • The surface course can vary in thickness but is usually between 150 mm (6 inches for light loading) and 300 mm (12 inches for heavy loads and high traffic). Figure shows a 300 mm (12 inch) surface course.
    62. 62. 62 PCC Surface Rigid Pavement Slab (Surface Course) Thickness
    63. 63. 63 Base Course • The base course is immediately beneath the surface course. It provides • Additional load distribution, • Contributes to drainage and frost resistance, • Uniform support to the pavement and • A stable platform for construction equipment. Bases also help and prevent sub grade soil movement due to slab pumping. Base courses are usually constructed out of: – Aggregates base. A simple base course of crushed aggregates has been a common option since the early 1900s and is still appropriate in many situations.
    64. 64. 64 – Stabilized aggregate or soil. Stabilizing agents are used to bind otherwise loose particles to one another, providing strength and cohesion. Cement treated bases (CTB s) can be built to as much as 20 - 25 percent of the surface course strength. – Dense-graded HMA. In situations where high base stiffness is desired base courses can be constructed using a dense-graded HMA layer. – Permeable HMA. In certain situations where high base stiffness and excellent drainage is desired, base courses can be constructed using an open graded HMA. Base Course
    65. 65. 65 – Lean concrete. Contains less Portland cement paste than a typical PCC and is stronger than a stabilized aggregates. Lean concrete bases (LCB s) can be built to as much as 25 - 50 percent of the surface course strength. A lean concrete base, functions much like a regular PCC surface course and therefore, it requires construction joints and normally cracks over time. These joints and cracks can potentially cause reflection cracking in the surface course. Base Course
    66. 66. 66 Completed CTB with Curing Seal Lean Concrete Base Material
    67. 67. 67 Sub-base Course • The sub-base course is the portion of the pavement structure between the base course and the sub- grade. It functions primarily as structural support but it can also: – Minimize the intrusion of fines from the sub-grade into the pavement structure. – Improves drainage. – Minimizes frost action damage. – Provides a working platform for construction. • The sub-base generally consists of lower quality materials than the base course but better than the sub-grade soils. Appropriate materials are aggregates and high quality structural fill.
    68. 68. 68 • Sub grade provides support to the overlying concrete slab. If it is of good quality then slab can be laid over it without providing sub-base otherwise if it is extremely poor then a sub-base layer should be incorporated . • For design purpose the only thing to know about sub-grade is its classification and the unit pressure coming from slab to sub- grade should be calculated for its selection. However, it must be resistant to moisture damages. Sub-grade
    69. 69. 69 Types of Rigid Pavement • Jointed Plain Concrete Pavement (JPCP)
    70. 70. 70 Types of Rigid Pavement • Continuously Reinforced Concrete Pavement (CRCP) Photo from the Concrete Reinforcing Steel Institute
    71. 71. 71 Rigid Pavement – Construction Slipform Fixed form
    72. 72. 72 Pavements Comparison Flexible pavements: • Deep foundations / multi layer construction • Energy consumption due to transportation of materials • Increasing cost of asphalt due to high oil prices Rigid pavements • Single layer • Generally last longer • May require asphalt topping due to noise / comfort issues
    73. 73. 73 Pavements Comparison
    74. 74. 74 Types of Pavement Failure • Failure criteria • Flexible Pavements • Fatigue Cracking, • Rutting, • Thermal Cracking, • Rigid Pavements • Fatigue Cracking, • Pumping or Erosion • Others: Faulting, spalling, joint deterioration
    75. 75. 75 Flexible vrs. Rigid Pavements
    76. 76. 76 Flexible vrs. Rigid Pavements
    77. 77. 77 Airport-Highway Pavements
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