FUNCTIONS OF
PAVEMENT COMPONENETS
[1] Soil Sub grade: - The soil sub grade is a layer of
natural soil prepared to receive the layers of pavement materials placed over
it. The loads on the pavement are ultimately received by the soil sub grade for
dispersion to the
earth mass. Therefore it is desirable that at least top 50cm layer of the sub
grade soil is well compacted under controlled conditions of optimum moisture
content and maximum dry density.
[2] Sub base: - These layers are made of broken
stones, bound or unbound aggregate. Sometimes in sub base course a layer of
stabilized soil or selected granular soil is also used. In some places boulder
stones or bricks are also used as a sub base or soiling course. Base course and
sub base courses are used under flexible primarily to improve the load
supporting capacity by distributing the load through a finite thickness.
[3] Wearing course: - The purpose of the wearing course
is to give smooth riding surface that it dense. It resists pressure exerted by
tyres and takes up wear and tear due to traffic. Wearing course also offers a
water tight layer against the surface water infiltration. In flexible pavement,
normally a bituminous surfacing is used as a wearing course.