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The pavement having high flexural strength and constructed utilizing RCC or PCC is called rigid pavement.
It is simply a concrete road (either RCC or PCC).
✔ Rigid Pavement is divided into different slabs during construction, and a small gap is provided between the slabs so that concrete doesn’t crack during expansion on summer days.
✔ This pavement transfers the wheel load to subgrade by slab action.
✔ Some examples of this pavement are PCC pavement, RCC pavement, and Prestressed concrete pavement.
1. Features of Rigid Pavement
Some features of rigid pavement are:
a. It transfers the wheel load to subgrade by slab action.
b. It requires joints.
c. Its initial construction cost is high.
d. Its durability is high.
e. It distributes wheel load uniformly.
f. It requires curing.
g. It doesn’t require rolling ( Compacting ) of the surface.
h. It has high flexural strength.
2. How Rigid Pavement is Different From Flexible Pavement
|S.N.||Flexible Pavement||Rigid Pavement|
|1.||It transfers the wheel load to subgrade by grain to grain mechanism.||It transfers the wheel load to subgrade by slab action.|
|2.||The initial construction cost is low.||The initial construction cost is high.|
|3.||It doesn’t require joints.||It requires joints.|
|4.||Durability is low.||Durability is high.|
|5.||It doesn’t distribute load uniformly. So, a good subgrade is required.||It distributes wheel load uniformly. So, there is no requirement for a good subgrade.|
|6.||There is no effect of temperature variation on stress variation.||Temperature variation affects the stress variation.|
|7.||The lifespan of flexible pavement is approximately 10 to 15 years.||The maximum lifespan of rigid pavement is approximately 20 to 30 years.|
|8.||Repair work is simple.||Repair work is complex.|
|9.||The maintenance cost is high.||The maintenance cost is low.|
It doesn’t require curing.
|It requires curing.|
|11.||Poor night visibility due to the use of asphalt.||Good night visibility due to the use of concrete.|
No glare due to sunlight.
(Glare: shine with a strong or dazzling light.)
|High glare due to sunlight.|
|13.||Easy to locate and perform underground works like repairing or finding pipes.||Hard to perform underground works.|
|14.||Its thickness is more.||Its thickness is less.|
|15.||The bearing capacity of the subgrade influences design.||The bearing capacity of the subgrade doesn’t influence its design.|
|16.||Aggregate and bitumen are used as the key materials.||Concrete and steel are used as key materials.|
|17.||Stability depends upon the interlocking of aggregates, particle friction, and cohesion.||Stability depends upon joints between the slabs of concrete.|
|18.||It is capable of resisting settlements to some extent.||The settlement is permanent. It is not capable of resisting settlement.|
|19.||It is susceptible to heat, oils, greases, and chemicals.||It is highly resistive to heat, oil, greases, and chemicals.|
|20.||Rolling ( Compacting ) of the surface is needed.||Rolling ( Compacting ) of the surface is not needed.|
|21.||It has a low flexural strength.||It has high flexural strength.|
|22.||The force of friction is less.||The force of friction is high.|
|23.||It is more comfortable for travel.||It is less comfortable for travel.|
3. Types of Rigid Pavement
There are two types of rigid pavement. They are:
1. Un-Reinforced Concrete Pavement (URCP)
The rigid pavement in which reinforcement is not provided is called unreinforced concrete pavement.
✔ Simply, it is a Plain Concrete Pavement.
✔ There are two types of URCP pavement. They are:
a.Jointed Dowelled Concrete Pavements(JDCP):
They are also called jointed plain concrete pavement(JPCP).
In this type of pavement, the load transfer mechanism is implemented using aggregate interlocks or dowel bars provided in transverse joints.
They have a joint spacing of 5 m -10 m.
b.Jointed Un-Dowelled Concrete Pavements(JUDCP):
This type of pavement is constructed when the traffic is very low. Dowel bars are not provided in JUDCP.
2. Reinforced Concrete Pavement(RCP)
The rigid pavement in which reinforcements are provided is called reinforced concrete pavement.
✔ They are used when traffic is high.
✔ There are two types of RCP. They are:
a.Jointed Reinforced Concrete Pavements(JRCP):
JRCP steel mesh or mat is provided at the centre of the slab.
The primary use of reinforcement is to control cracking rather than a structural purpose.
It can be used for low or medium-traffic roads.
b.Continuous Reinforced Concrete Pavements(CRCP):
Continuous reinforcements are provided on this pavement.
They are mainly used for constructing high-traffic roads.
The gap between the slab is also eliminated. They are mainly used where the strength of sub-grade soil is very less.
This pavement can resist different types of load and adverse weathering effects easily.
|Read More: Flexible Pavement|
4. Requirements of Good Rigid Pavement
~ It should have a long-life design with low maintenance cost.
~ It should be waterproof enough to protect sub-grade soil.
~ It should have a high coefficient of friction to resist skidding.
~ It should be smooth enough to provide comfort to the users.
~ It should be structurally strong to withstand all types of loads.
5. Construction Steps of Rigid Pavement
a. Preparation of subgrade
~ The first step of rigid pavement construction is the preparation of subgrade.
~ In this step, cutting and filling work is done according to the requirement, and compaction work is carried out. The slight application of water should be made during the compaction work, i.e. compaction should be done at optimum moisture content.
b. Provision of sub-base course
~ Sub-base course is provided when the subgrade is weak. In the case of a strong sub-grade, there is no need to give a sub-base course.
~ Sub-base course is a mixture of soil & small stone pieces. After the provision of the sub-base, it should be compacted.
c. Preparation of Base Course
~ After sub-base course; built non-erosive base coarse with boulders and stones maintaining slopes for water disposal.
~ Voids and gaps between the boulders or big stones are filled with small stones.
~ Strong stones with irregular shapes are generally preferred for the base.
~ Thickness of base course should be a minimum of 6 inches.
d. Surface Course Preparation
~ Construct the concrete slab above the base course (either with RCC or PCC ).
~ Their thickness should not be less than 12 inches for high-traffic roads.
~ For low-traffic roads, their thickness should not be less than 6 inches.
6. Facts of Rigid Pavement
1. They are also called single-layer pavement.
2. They may last up to 40 years if timely maintained and cared for.
3. They may require asphalt for toping to reduce the noise during vehicle operation.
4. The vehicle operation cost of rigid pavement is low.
5. They are cheaper while considering the life-cycling cost.
6. Maintenance cost is very low.
7. Advantages of Rigid Pavement
~ Low maintenance and operation cost.
~ Higher life span.
~ It has high flexural strength.
~ It has good resistance to petroleum products, oils, and chemicals.
~ More environment-friendly than flexible pavement.
~ It distributes loads in the broader area and can bear a large load due to slab action.
8. Disadvantages of Rigid Pavement
~ High initial cost required for construction.
~ Maintenance of rigid pavement is more complex than flexible pavement.
~ Requires at least 28 days of curing before high traffic movement because concrete gains its 99% efficiency/strength in 28 days.
~ Any excessive deformations occurring due to heavier wheel loads are not recoverable in this pavement type( settlement is permanent).
|Read More: Difference between rigid and flexible pavement|
|Read More: Flexible Pavement|
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