1. Compaction
N. Sivakugan
Duration = 10 minutes

2. What is compaction? + water =
A simple ground improvement technique, where the soil is densified through external compactive effort.
Compactive effort
+ water =

3. Compaction Curve Soil grains densely packed
Water content
Dry density (d)
Soil grains densely packed
- good strength and stiffness
- low permeability
d, max
optimum water content

4. Compaction Curve
What happens to the relative quantities of the three phases with addition of water?
soil
water
air
Water content
Dry density (d)
difficult to expel all air
lowest void ratio and highest dry density at optimum w

5. Zero Air Void Curve - corresponds to 100% saturation S<100%
Water content
Dry density (d)
- corresponds to 100% saturation
Zero air void curve (S=100%)
S<100%
S>100% (impossible)
All compaction points should lie to the left of ZAV curve

6. Effect of Compactive Effort
Water content
Dry density (d)
Increasing compactive effort results in:
E2 (>E1)
Lower optimum water content
Higher maximum dry density E1

7. Compaction and Clay Fabric
Water content
Dry density (d)
Higher water content or higher compactive effort gives more dispersed fabric.
more dispersed fabric
more dispersed fabric

8. Line of Optimum Compaction curves for different efforts
Water content
Dry density (d)
Line of optimum
Compaction curves for different efforts

9. Filed Compaction Smooth-wheel roller Vibratory roller
Different types of rollers (clockwise from right):
Smooth-wheel roller
Vibratory roller
Pneumatic rubber tired roller
Sheepsfoot roller

10. Field Compaction Smooth Wheeled Roller
Compacts effectively only to mm; therefore, place the soil in shallow layers (lifts)

11. Field Compaction Vibrating Plates for compacting very small areas
effective for granular soils

12. Field Compaction
Sheepsfoot Roller
Provides kneading action; “walks out” after compaction
Very effective on clays

13. Field Compaction Provides deeper (2-3m) compaction. e.g., air field
Impact Roller
Provides deeper (2-3m) compaction. e.g., air field

14. e.g., 1 test per 1000 m3 of compacted soil
Compaction Control
a systematic exercise where you check at regular intervals whether the compaction was done to specifications.
e.g., 1 test per 1000 m3 of compacted soil
Minimum dry density
Range of water content
Field measurements (of d) obtained using
sand cone
nuclear density meter

15. Laboratory Compaction Test
to obtain the compaction curve and define the optimum water content and maximum dry density for a specific compactive effort.
hammer
Modified Proctor:
Standard Proctor:
5 layers
25 blows per layer
3 layers
25 blows per layer
1000 ml compaction mould
4.89 kg hammer
450 mm drop
2.6 kg hammer
310 mm drop

16. Compaction Control Testw d
Compaction specifications
Compare!
d,field = ? wfield = ?
compacted ground

17. Dynamic Compaction - pounding the ground by a heavy weight
Suitable for granular soils, land fills and karst terrain with sink holes.
solution cavities in limestone
Pounder (Tamper)
Crater created by the impact
(to be backfilled)

18. Dynamic Compaction
Pounder (Tamper) Mass = 5-30 tonne Drop = m

19. Dynamic Compaction

20. Vibroflotation Suitable for granular soils Practiced in several forms:
vibro–compaction
stone columns
vibro-replacement
Vibroflot (vibrating unit) Length = 2 – 3 m Diameter = 0.3 – 0.5 m Mass = 2 tonnes
(lowered into the ground and vibrated)

21. Vibroflotation

22. Vibroflotation

23. Vibroflotation

24. Vibroflotation

25. Vibroflotation

26. Vibroflotation

27. Stone Columns vibrator makes a hole in the weak ground hole backfilled
..and compacted
Densely compacted stone column

28. Blasting For densifying granular soils Aftermath of blasting
Fireworks?

29. Earthmoving Equipment
David and Goliath?
This is an Australian excavator, with height of a 3-storey building
Large Excavator (see minivan on left for scale)

30. Earthmoving Equipment
Grader for spreading soil

31. Earthmoving Equipment
Bulldozer for spreading soil evenly

32. Earthmoving Equipment
Loader

33. Earthmoving Equipment
Backhoe

34. Earthmoving Equipment
Crawler mounted Hydraulic Excavator

35. Earthmoving Equipment
Rock Breaker