ROAD PAVEMENT& ITS TYPES: -The road
pavement is the actual
surface on which the vehicles will travel. Its purpose is twofold, to provide
friction for the vehicles and to transfer normal stresses to the underlying
soils. Pavement is two types:
[1] 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 sub grade. Water
bound macadam roads and stabilized soil roads with or without asphaltic
toppings are examples of flexible pavements.
[2] Rigid Pavements:A rigid pavement is constructed
from cement concrete or reinforced concrete slabs. Grouted concrete roads are
in the category of semi-rigid pavements.The design of rigid pavement is based
on providing a structural cement concrete slab of sufficient strength to
resists the loads from traffic. The rigid pavement has rigidity and high modulus
of elasticity to distribute the load over a relatively wide area of soil.
Difference between Flexible
Pavements and Rigid Pavements:
S.N
|
Flexible Pavements
|
Rigid Pavements
|
1
|
It consists of a series of layers with the
highest quality materials at or near the surface of pavement.
|
It consists of one layer Portland cement
concrete slab or relatively high flexural strength.
|
2
|
It reflects the deformations of subgrade
and subsequent layers on the surface.
|
It is able to bridge over localized
failures and area of inadequate support.
|
3
|
Its
stability depends upon the aggregate interlock, particle friction and
cohesion. |
Its
structural strength is provided by the pavement slab itself by its beam
action. |
4
|
Pavement
design is greatly influenced by the subgrade strength. |
Flexural
strength of concrete is a major factor for design. |
5
|
It
functions by a way of load distribution through the component layers |
It
distributes load over a wide area of subgrade because of its rigidity and
high modulus of elasticity. |
6
|
Temperature
variations due to change in atmospheric conditions do not produce stresses in
flexible pavements. |
Temperature
changes induce heavy stresses in rigid pavements. |
7
|
Flexible
pavements have self healing properties due to heavier wheel loads are
recoverable due to some extent. |
Any
excessive deformations occurring due to heavier wheel loads are not
recoverable, i.e. settlements are permanent. |
