Types of pavement

Types of Pavement
N.M.P.I (S.Y) CIVIL ENGINEERING Page 1
INDEX
Sr. No Particulars Page. No.
01. Title 02.
02. Introduction 02.
03. Types of Pavement 05.
04. Flexible Pavement 06.
05. Semi Rigid Pavement 08.
06. Rigid Pavement 11.
07. Earthen Road 13.
08. WBM Road 15.
09. Conclusion 17.
10. Reference 18.

Types of Pavement
Title
Types of Pavement
Introduction:-
Development of a country depends on the connectivity of various places with adequate
road network. Roads are the major channel of transportation for carrying goods and
passengers. They play a significant role in improving the socio-economic standards of a
region. Roads constitute the most important mode of communication in areas where
railways have not developed much and form the basic infrastructure for the
development and economic growth of the country. The benefits from the investment in
road sector are indirect, long-term and not immediately visible. Roads are important
assets for any nation. However, merely creating these assets is not enough, it has to be
planned carefully and a pavement which is not designed properly deteriorates fast. India
is a large country having huge resource of materials. If these local materials are used
properly, the cost of construction can be reduced. There are various type of pavements
which differ in their suitability in different environments. Each type of pavement has
it’s own merits and demerits. Despite a large number of seminars and conference, still
in India, 98% roads are having flexible pavements. A lot of research has been made on
use of Waste materials but the role of these materials is still limited. So there is need to
take a holistic approach and mark the areas where these are most suitable.

Types of Pavement
Subgrade:
 It is the soil layer beneath the pavement which bears the design load, receives
infiltration water, and is subject to ground water infusion due to seasonal
fluctuations or upward capillary migration.
 Subgrade bearing capacity, uniformity, and permeability are key factors in
determining various pavement layers thickness.
Aggregate Base and Subbase:
 The base layer consists of a grades aggregate foundation that transfers the
pavement load to the Subgrade in controlled radiating manner.
 Heavy-duty pavements or weak subgrades, usually require an additional layer of
base material, called a subbase, which also consists of a clean but coarser-
graded aggregate layer.
 Both aggregate base and subbase typically extend beyond the pavement edge to
provide lateral support and to prevent uneven subgrade loading.
Base Course
 The layer or layers of specified or selected material designed thickness placed
on a sub base to support a surface course.
Pavement:
 The pavement material receives traffic wear and transfers loads to the base and
subgrade.
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.

Types of Pavement
Requirements of pavement structure
 Sufficient thickness to spread loading to a pressure intensity tolerable by
subgrade
 Sufficiently strong to carry imposed stress due to traffic load
 Sufficient thickness to prevent the effect of frost susceptible subgrade

Types of Pavement
Types of Pavements
 There are two types of pavements based on design considerations i.e. flexible
pavement and rigid pavement. Difference between flexible and rigid pavements
is based on the manner in which the loads are distributed to the subgrade.
 Before we differentiate between flexible pavements and rigid pavements, it is
better to first know about them. Details of these two are presented below:
Flexible Pavements
 Flexible pavement can be defined as the one consisting of a mixture of asphaltic
or bituminous material and aggregates placed on a bed of compacted granular
material of appropriate quality in layers over the subgrade. Water bound
macadam roads and stabilized soil roads with or without asphaltic toppings are
examples of flexible pavements.
 The design of flexible pavement is based on the principle that for a load of any
magnitude, the intensity of a load diminishes as the load is transmitted
downwards from the surface by virtue of spreading over an increasingly larger
area, by carrying it deep enough into the ground through successive layers of
granular material.

Types of Pavement
Flexible Pavements
 Bitumen has been widely used in the construction of flexible pavements for a
long time. This is the most convenient and simple type of construction. The cost
of construction of single lane bituminous pavement varies from 20 to 30 lakhs
per km in plain areas. In some
 applications, however, the performance of conventional bitumen may not be
considered satisfactory because of the following reasons:
 In summer season, due to high temperature, the bitumen becomes soft resulting
in bleeding, rutting and segregation finally leading to failure of pavement.
 In Winter season, due to low temperature, the bitumen becomes brittle resulting
in cracking, raveling and unevenness which makes the pavement unsuitable for
use.
 In rainy season, water enters the pavement resulting into pot holes and
sometimes total removal of bituminous layer.
 In hilly areas, due to sub zero temperature, the freeze thaw and heave cycle
takes place. Due to freezing and melting of ice in bituminous voids, volume
expansion and contraction occur. This leads to pavements failure.
 The cost of bitumen has been rising continuously. In near future, there will be
scarcity of bitumen and it will be impossible to procure bitumen at very high
costs.
 Recently, a large number investigations have demonstrated that bitumen
properties can be improved using an additive or a chemical reaction
modification.
The use of polymer modified bitumen's (PMBs) to achieve better asphalt pavement
performance has been observed for a long time. The improved functional properties
include permanent deformation, fatigue and low temperature cracking. The properties
of PMVs are dependent on the polymer characteristics and content and bitumen nature,
as well as the blending process. Despite the large number of polymeric products, there
are relatively few types which are suitable for bitumen modification (2). The polymers
that are used for bitumen modification can be divided onto two broad categories,
namely plastomers and elastomers. Elastomers have a characteristically high elastic
response and, therefore, resist permanent deformation by stretching and recovering
their initial shape. Plastomers from a tough, rigid, three dimensional network to resist
deformation. The thermoplastic rubber, styrene butadiene-styrene (SBS), is an example
of an elastomer and the thermoplastic polymer, ethylene vinyl acetate (EVA), is
an example of a plastomer. One of the principal plastomers used in pavement
applications is the semi-crystalline copolymer, ethylene vinyl acetate (EVA). EVA
polymers have been use in road construction for more than 20 years in order to improve
both the workability of the asphalt during construction and its deformation resistance in

Types of Pavement
service. Figure 1 to 6 show the effect of these modifiers to bitumen before and after
ageing.

Types of Pavement
Semi Rigid Pavements
The pavements constructed using the waste materials, which are more strong the
traditional aggregates may be treated as Semi-Rigid Pavement. A lot of research work
has been done in this direction. But the work in terms of real construction is not
visible.
Some examples of real construction are given below:
Visakhapatnam Steel Plant (VSP) at Visakhapatnam (AP) is one of the major steel
plants producing steel in the country. Granulated Blast Furnace Slag (GBFS) is also
generated as a by-products of steel. Prior to 1991, a major portion of GBFS was being
used by the cement manufacturing industries located in the nearby areas but its
utilization in this industry has been decreasing gradually. This material has, therefore,
been piling up gradually due to increased production as a waste in the plant area an
posing serious problem for its disposal. Two roads namely Ankapalli-Pudimadaka Road
(AP road) – a MDR and Bheemunipatnam-Narsipatnam road (NB road) – a State
Highway were selected for test track construction. The existing width of the road
pavement was about 3.5m and as per state PWD programme, has to be increased to
5.5m by 1m widening the carriageway on both sides of the road. The pavement
thickness worked out to be 425mm for the traffic parameter of 3 million standard axle
(msa) for BN road and 480mm for the traffic parameter of 1.25 msa in case of AP road.
The pavement compositions were then, worked out considering the strength of GBFS,
GBFS subgrade soil/moorum mixes for the two roads.
In another project, Conventional moorum, gravel, sand or lime/cement stabilised local
soil were used in subbase layer of a road pavement. In order to compare the structural
performance of these materials with the steel industry wastes, a small test track was
constructed at Bokaro. The selection of different test sections was made on the basis of
laboratory test results as discussed in the previous sections. The details of the test
sections are as follow:
In order to structurally evaluate the different specifications/test sections, plate load tests
were conducted on each section using a 30cm diameter plate. The load deflection
values were recorded by applying incremental load. Plate load test was also carried out
on subgrade soil. Since with an ordinary truck, only limited magnitude of reaction can
be obtained, a heavy 35 tonnes dumper was used for carrying out place load test. Based
on Burmister's two layer theory, the modulus of elasticity for different specifications
were worked out and are given in Table-2. The ratings based on load carrying capacity
of different sections are also indicated in the same table.

Types of Pavement
Similarly, Bandamunda Jaraikala road, which is a major district road near
Rourkela, was chosen for construction using the waste material from
Rourkela Steel Plant. For the experimental test sections on Bandamunda
Jaraikala Road, Rourkela. Where 1.8m widening on both the sides of the
existing road was proposed, a total number of 11 test sections using steel
plant wastes were laid. During rainy season, heavy rains are there and
water passes across the road. While formulating specifications, attempts
were made to make maximum utilization of steel plant by-product such as
BF slag, SMS, granulated slag and flyash, etc. It includes one control test
section, which comprises conventional road building materials for
comparison purpose. It shows that except right portion of sections 1,2 all
sections were structurally

Types of Pavement
Semi-rigid pavements represent an intermediate state between the Flexible and the
Rigid pavement. The flexural strength of such type of pavment is much lower than the
concrete slab, but it derives support by the lateral distribution of loads through the
pavement depth as in flexible pavement.
Lean cement concrete, soil cement and lime-puzzolanic concrete construction are
examples of semi-rigid pavements.

Types of Pavement
Rigid Pavements
Rigid pavements, though costly in initial investment, are cheap in long run because of
low maintenance costs. There are various merits in the use of Rigid pavements
(Concrete pavements) are summarized below:
 Bitumen is derived from petroleum crude, which is in short supply globally and
the price of which has been rising steeply. India imports nearly 70% of the
petroleum crude. The demand for bitumen in the coming years is likely to grow
steeply, far outstripping the availability. Hence it will be in India's interest to
explore alternative binders. Cement is available in sufficient quantity in India,
and its availability in the future is also assured. Thus cement concrete roads
should be the obvious choice in future road programmes.
 Besides the easy available of cement, concrete roads have a long life and are
practically maintenance-free.
 Another major advantage of concrete roads is the savings in fuel by commercial
vehicles to an extent of 14-20%. The fuel savings themselves can support a
large programme of concreting.
 Cement concrete roads save a substantial quantity of stone aggregates and this
factor must be considered when a choice pavements is made,
 Concrete roads can withstand extreme weather conditions – wide ranging
temperatures, heavy rainfall and water logging.
 Though cement concrete roads may cost slightly more than a flexible pavement
initially, they are economical when whole-life-costing is considered.
 Reduction in the cost of concrete pavements can be brought about by
developing semi-self-compacting concrete techniques and the use of closely
spaced thin joints. R&D efforts should be initiated in this area.

Types of Pavement
Advantages of Rigid Pavement
 Rigid lasts much, much longer i.e 30+ years compared to 5-10 years of flexible
pavements.
 In the long run it is about half the cost to install and maintain. But the initial
costs are somewhat high.
 Rigid pavement has the ability to bridge small imperfections in the subgrade.
 Less Maintenance cost and Continuous Traffic and Flow.
 High efficiency in terms of functionality

Types of Pavement
Earthen Road
A dirt road or track is a type of unpaved road made from the native material of the land
surface through which it passes, known to highway engineers as subgrade material. Dirt
roads are suitable for vehicles; a narrower path for pedestrians, animals, and possibly
small vehicles would be called a dirt track—the distinction is not well-defined.
Unpaved roads with a harder surface made by the addition of material such as gravel
and aggregate (stones), might be referred to as dirt roads in common usage but are
distinguished as improved roads by highway engineers. (Improved unpaved roads
include gravel roads, laterite roads, murram roads and macadamized roads.)
Compared to a gravel road, a dirt road is not usually graded regularly to produce an
enhanced camber to encourage rainwater to drain off the road, and drainage ditches at
the sides may be absent. They are unlikely to have embankments through low-lying
areas. This leads to greater waterlogging and erosion, and after heavy rain the road may
be impassable even to off-road vehicles. For this reason, in some countries, such as
Australia and New Zealand, they are known as dry-weather roads.
Dirt roads take on different characteristics according to the soils and geology where
they pass, and may be sandy, stony, rocky or have a bare earth surface, which could be
extremely muddy and slippery when wet, and baked hard when dry. They are likely to
become impassable after rain. They are common in rural areas of many countries, often
very narrow and infrequently used, and are also found in metropolitan areas of many
developing countries, where they may also be used as major highways and have
considerable width.
Terms similar to dirt road are dry-weather road, earth road, or the "Class Four
Highway" designation used in the People's Republic of China. A track, dirt track, or
earth track would normally be similar but less suitable for larger vehicles.

Types of Pavement
While most gravel roads are all-weather roads and can be used by ordinary cars, dirt
roads may only be passable by trucks or four-wheel drive vehicles, especially in wet
weather, or on rocky or very sandy sections. It is as easy to become bogged in sand as it
is in mud; a high clearance under the vehicle may be required for rocky section.Driving
on dirt roads requires great attention to variations in the surface and it is easier to lose
control than on a gravel road

Types of Pavement
WBM ROAD
WBM Stands for Water Bound Macadam which is the most commonly used road
construction procedure for over more than 190 years.Pioneered by Scottish Engineer
John Loudon McAdam around 1820 Macadam is a type of Road Construction. The
broken stones of base and surface course,if any are bound by the stone dust is presence
of moisture is called WBM Roads.
Macadam means the pavement base course made of crushed or broken aggregate
mechanically interlocked by rolling and the voids filled with screening and binding
material with the assistance of water.WBM may be used as a sub-base,base or a surface
course.The thickness of each compacted layer of WBM ranges from 10cm to 7.5cm
depending on size and the gradation of aggregate used.

Types of Pavement
Construction Procedure:
1. Prepare the foundation for receiving the WBM course.
2. Lateral confinement may be done by compacting the shoulder to advance,to a
thickness equal to that of the compacted WBM layer and by trimming the inner
side vertically.
3. Spreading of Coarse Aggregate.
4. Compaction of coarse aggregate is done by wheeled power roller of capacity 6
to 10 tonnes or alternately by an equivalent vibratory roller.
5. Compaction of WBM Road by Mechenical Road Roller
6. Dry screening is applied gradually over the surface to fill the interstices in these.
7. The surface is sprinkled with water,swept and rolled.
8. Binding material is applied at a uniform and slow rate at two and more layers.
9. WBM Coarse is allowed to set overnight.

Types of Pavement
Conclusion
We get the information regarding flexible pavement ,rigid,wbm,and earthen road
and also we know the difference between all type of pavement
Also we know that which type of pavement is used for perticuler area based on its
utilization and importance. We get information regaeding type of layer used in various
pavement

Types of Pavement
References
 www.slideshare.net/malrarenu/types-of transportation-67439828
 www.slideshare.net/akisamant/transportation-ppt
 www.slideshare.net/estefitovar/trabajo-ppt-36260959
 www.splung.com
 Textbook of Highway Engineering
 Reference Book of Highway Engineering

Types of pavement

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