The nature of soil dictates the type of compacting
equipment required, and the dry density which can be achieved. After the
compacting equipment is selected, its average output can be calculated as
under:
Compaction in m3/lit = WSTEC/P
Where,
W = Width compacted per pass (M)
S = Compactor speed in M/h
T = Thickness of compacted layer in m2
E = Job efficiency factor
C = Compacting factor
F = Number of passes required-varies from 4 to 6
And the approximate value of the compacting factor for
the changing state of soil. In the absence of actual data, the compacting
factor can be assumed as:
Compacting Factor for Different Types of Soil
|
|
Compacted Volume
|
Loose Volume
|
In-place Volume
|
In-place Dry Density
|
|
Common earth
|
1.0
|
1.41
|
1.18
|
1.8
|
|
Sand
|
1.0
|
1.21
|
1.18
|
1.7
|
|
Clay
|
1.0
|
1.48
|
1.11
|
1.9
|
|
Gravel
|
1.0
|
1.17
|
1.11
|
2.0
|
|
Crushed stone
|
1.0
|
1.30
|
0.75
|
2.2
|
Notes:
- The above data can be used for initial planning purposes. However, trials are necessary to determine the optimum moisture content, loose layer (lift) thickness, roller weight and the number of passes that yield a certain compacted thickness of the layer having a specified field dry density.
- It is necessary to assess the requirement of water for compaction so as to develop a water distribution system including requirement of water tenders.
Water requirement in litres per hour = weight of loose
soil to be compacted per hour in kg x (optimum moisture content-natural
moisture content).
For example – water required per hour for compacting
loose soil being spread by a shovel and dozer at the rate of 230 m3/h
for a soil having density of 1.5 g/cm3 and 8% moisture content,
needing 12% optimum, moisture content for compaction
= 230 x 106 x 1.5 x (12 – 8 / 100) x
(1/1000)
= 13800 liters water/hour
