This document discusses different types of rollers used for soil compaction. It begins by introducing rollers and their purpose in compacting soil to increase strength. There are four main types discussed: smooth wheeled rollers, pneumatic tire rollers, sheep foot rollers, and vibrating/tamping rollers. Each type is suited for different soil compositions and compaction methods. For example, pneumatic tire rollers provide kneading action while vibrating rollers use vibration to minimize friction and compact soils from the bottom up. Key specifications for each roller type are also outlined.

1. CHAPTER- FIVE
ROLLERS
By: Debas D.
1
Ambo University
Department of Mechanical engineering

2. INTRODUCTION
 A roller is a compactor vehicle used to compact soil,
gravel, concrete, or asphalt in the construction work.
 compaction is the act of densifying the soil by
pressing soil particles together into close contact,
resulting in the expulsion of air and/or water from the
soil mass.
 The result of the compactive effort is to increase the
strength of an earth till or embankment.
 Compaction of the soil is obtained by various actions
and roller machines.
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3. INTRODUCTION
 Compaction of soil is attained by applying energy to
soil by one of the methods given below.
1. Static Weight
2. Impact
3. Vibration
4. Kneading action
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4. INTRODUCTION
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5. INTRODUCTION
Static Weight:
 Applied by smooth wheel rollers and pneumatic tyre
rollers.
 Compaction can not reach lower strata because of
internal friction of soil.
 So this compaction is especially good for granular soils
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6. INTRODUCTION
Impact Compaction:
 The equipment used for impact compaction are
tamping rollers and rammers.
 Impact reduces the internal friction of soil and
particles start moving towards voids easily.
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7. INTRODUCTION
Vibrating:
 Vibrating rollers and vibrating plates are used.
 In this system impact force penetrates down to
great depth.
 Vibration minimizes the internal friction of particles
and smaller particles move down to voids easily.
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8. INTRODUCTION
Kneading Action:
 In this system the compaction starts from a lower
level and comes upward.
 Kneading action is actually the application of shear
stress to soil.
 Sheep's foot roller (tamping rollers) and pneumatic
tire rollers are used.
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9. Types of rollers
There are different types of rollers:
1. Smooth wheeled roller
2. Pneumatic tyre roller
3. Sheep foot roller
4. Vibrating and tamping roller
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10. 1. Smooth wheeled roller
 Smooth wheeled rollers are of two types:
i. Static smooth wheeled roller
ii. Vibrating smooth wheeled roller
 The compacting efficiency depends on weight
,width and diameter of each roller.
 Suitable for wide range of soil preferably granular
soils such as sand, gravel, and crushed stones.
 It is also effective in smoothing surface of soils that
have been compacted by tamping rollers
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11. 1. Smooth wheeled roller
 The desirable speed and number of passes for
appropriate compaction of soil depends on the type
of soil and varies from location to location.
 In case of vibrating smooth wheeled rollers, the
drums are made to vibrate by employing rotating or
reciprocating mass.
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12. Figure: Smooth wheeled roller
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13. 2. Pneumatic tyre roller
 In this type number of pneumatic wheels are
mounted on two or more axels under a loading
platform ,pulled by tractor.
 In addition to the direct pressure due to rolling
there is also slight kneading action.
 They may also be small or large tired units. The
small tire units are usually have two tendon axle
with 4 to 9 tires on each axels.
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14. Pneumatic tyre roller
 Major advantages of Pneumatic tyre roller
are the ability to control the ground contact
pressure by:
a) Altering the weights of machines,
b) Increasing the number of wheels,
c) Increasing the tyre width
d) Changing the contact area of the tyre by
altering the contact pressure.
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15. Pneumatic tyre roller
Figure: Pneumatic tyre roller
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16. Pneumatic tyre roller
Tyre Overlap:
• There is some gap between the tyres provided in
front and rear tyres.This gap is filled with the
movement of tyre.
• To achieve uniform compaction effect and avoid
tyre marks, front and rear tyre are over lap.
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17. Pneumatic tyre roller
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18. 3.Sheep foot roller
This type of roller Contains a steel drum
including a number of projecting steel feet.
During rolling operation the soil under the
projecting feet get compacted and also
considerable kneading action to the soil.
When the drum rotates, the pads out of the soil
they kick to the material because of their shape.
They are suitable for compacting all fined
grained material but is generally not suitable for
use of cohesion less granular material.
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19. Figure:Sheep foot roller
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20. 4. Vibrating and tamping roller
Vibrating roller
 Vibratory compactor enhance the performance of
static weight machines by adding dynamic forces,
usually achieved by a rotating eccentrically
weighted shaft mounted inside the roller.
 Vibrations of vibrators arrange the particles by first
disturbing even the arranged ones.
 Vibrators are turned off during the reversed motion
of roller.
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21. Vibrating roller
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22. Vibrating roller
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23. Vibrating roller
 Very useful for granular materials.
 Combination of vibration and pressure is applied.
 Not good for cohesive soils.
They could be:
 Vibrating tamping rollers
 Vibrating steel-drum (smooth wheel) rollers
 Vibrating pneumatic rollers
 Vibrating plates or shoes (manually operated rammers)
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24. Main components of vibrating roller
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25. PRINCIPLE OF VIBRATORY ROLLERS
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The vibration is produced
by rotating the off-center
weights

26. Principle of vibratory compaction:
 Grains of soil are effected by periodically alternating
inertial forces.
 These forces make grain particles ‘floating’, so ordering is
progressed without friction.
 At vibratory compaction low amplitude high frequency
excitation is used for loose soil or for deep layers.
 High amplitude low frequency excitation is used for
cohesive soils in thin layers.
 Frequency of excitation should be close to characteristic
frequency of the soil
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27. VIBRATORY ROLLERS - AMPLITUDE
 It is the vertical displacement of the roller drum.
Amplitude of vibration is directly related to the
impact force.
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28. VIBRATORY ROLLERS - FREQUENCY
 The Frequency is Drum impacts per minute
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29. Effect of Characteristics of Vibratory Roller
• High amplitude and low frequency are used to
compact soft soils and to reach deeper zones while
low amplitude and high frequency are used for stiff
soils and shallow depth.
• Further High amplitude and low frequency setting
is used for compaction of a thick layer whereas low
amplitude and high frequency setting is used for
the compaction of thin layer.

30. • For example on a first pass the roller might use a high
amplitude and low frequency but at the fourth pass, it sets
itself with a low amplitude and high frequency.
• The effectiveness of compaction depends upon several
factors involving interaction between the equipment and the
soil being compacted. These factors include.
a) Operating Frequency :
 Frequency control the number of impacts per meter
between the drum and ground.
 Maximum compaction occurs when it vibrates near
resonant frequency.

31. Effect of Frequency
Fig . Effect of Frequency

32. b) Amplitude of vibration:
• It is the vertical displacement of the roller drum.
• Amplitude of vibration is directly linked to the impact force.
• Higher amplitude results in achieving higher thickness of
compacted material at minimum number of passes, thereby
improving productivity.
• Amplitude determines impact force
Fig. Effect of Amplitude

33. C) Speed of Travel :
• Slow speed results in closeness of impacts, whereas high speed results
in increase in the spacing of impacts.
• An even lower speed may be required for the initial passes.
Impact Spacing
Fig. Effect of Travel Speed

34. Ways of excitation:
 circular excitation: simple construction, single exciter unit eccentric should
always rotate in , eccentric should always rotate in direction of advancing
 directed excitation: double exciter unit, generates both compressing and
sharing forces in the soil simultaneously
 oscillation: the two exciter masses generate moment at the surface of the
drum creating compressing and sharing forces in the soil so , so grains are
ordered horizontally. Vertical force is provided by the weight of the drum
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35. 35

36. Tamping foot roller
 These rollers usually have steel padded wheels and
can be equipped with a small blade to help for
leveling the layer.
 As tamping rollers moves over the surface the feet
penetrate into the soil to mix and compact the soil
from bottom to top of the layer.
 Tamping foot roller is best dedicated to fine grained
soils.
Figure: Tamping foot roller
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37. Output of Compactors
 Compacted earthwork is measured in terms of
compacted volume in the fill.
 This can be found by multiplying the compacted
area by the thickness of the compacted layer.
 Usually the number of passes required to attain
necessary soil density is specified, and should be
considered while estimating production.
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38. Specification of rollers
 Caterpillar CS54B Smooth Drum Vibratory Soil Compactor
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39. Specification of rollers
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