Granular subbase and equipments used for its construction

Granular sub-base and equipment used for its construction (Highway Engineering)

1. HIGHWAY ENGINEERING
PRESENTATION
By : Shubham Shama
Roll No. 14142
Deptt.-CED

3. Laid between subgrade and pavement.Laid between subgrade and pavement.
To serve as an effective drainage layer to drain To serve as an effective drainage layer to drain
off the water entering in to the pavement layers.off the water entering in to the pavement layers.
 To serve as the structural component of the To serve as the structural component of the
flexible pavement structure by distributing wheelflexible pavement structure by distributing wheel
load stresses transmitted through the surface course and granular base course.load stresses transmitted through the surface course and granular base course.
To prevent moisture migration from subgrade.To prevent moisture migration from subgrade.

4. Crushers are mainly used to reduce the size of large stone or rock to Crushers are mainly used to reduce the size of large stone or rock to
smaller uniform sized aggregates. smaller uniform sized aggregates.
They are set up in the nearby stone quarries to reduce transportation cost.They are set up in the nearby stone quarries to reduce transportation cost.

5. (wearing due to frictional rubbing)
1.Pressure1.Pressure
2. Impact2. Impact
3. Attrition3. Attrition
4. A combination of these 4. A combination of these
operationsoperations..

6. Jaw CrusherJaw Crusher
Gyratory CrusherGyratory Crusher
Cone Crusher
In Actual
Field
Roll Crusher

7. Tipper is a very large truck designed to carry heavy loads
and can be emptied by raising front of the carrier to allow
the contents to slide out from the back using hydraulic arm
attached to the carrier

8. In Granular Sub-Base (GSB) construction,
aggregates are needed to be
distributed according to their sizes.
This purpose is fulfilled by using a machine
known as aggregate distributor.

9. Motor Grader is a machine used
to spread the sub-base material
to uniform thickness and specified
cross slope by adjusting the blade
of the grader.

10. Granular Sub-Base layer is watered to Optimum Moisture
Content and
then it is compacted by rolling.
If the compacted thickness of the layer is 100mm or lesser, an
ordinary
smooth wheeled roller is used.
For compacted thickness exceeding 100mm, compaction is
done by
Vibratory roller of static weight 10 tons or more.

Rolling is done starting from the lower edge proceeded towards
the
upper edge of divided carriageway with rolling speed limited to
5
KMPH.
Rolling is continued till at least 98% of the maximum density of
the
material is achieved.