Cross-section of a road showing its
component parts & their function.
Sub-Grade:-
I.
The
sub-grade is generally consider to be the soil over which the highway is
constructed.
II.
It provided support to the pavement from
below.
III.
The main
function of sub-grade is that due to lack of sub-grade strength results in many
defects in pavement.
Base
& Sub-Base:-
·
In
Flexible Pavement:
I.
To improve
the load bearing capacity by distributing the load through finite thickness.
II.
To
dissipated the destructive wheel load to prevent shear and consolidation of
deformation.
·
In
Rigid Pavement:
I.
Preventing pumping out of soil slurry through
joints and cracks.
II.
Protection of Sub-Grade against frost action.
Wearing/Surface
Course:-
I.
To provide
smooth riding surface.
II.
To resist
pressures exerted by tire.
III.
To take wear
and tear.
IV.
To prevent
infiltration of rain water into the pavement and sub-grade.
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