Roller Compaction

Roller Compaction

Group 5 13-CE-05 13-CE-15 13-CE-26 13-CE-39

Department of Civil Engineering, MUST AJK

Purpose OF Compaction

• To increase the density

• To improve the shearing resistance

• To minimize the future settlement

• To reduce the permeability

Factors Affecting Compaction

• Compaction Energy

• Moisture Content

• Soil Type

• Layer Thickness

• Contact Pressure

• Number of Roller Passes

• Speed of Rolling

Methods of Compaction

• Kneading Compaction

• Static Compaction

• Dynamic Compaction

• Vibratory Compaction

Types of Compacting Equipment

Type of equipment required mainly depends on soil type:

• Smooth Wheel Rollers

• Sheepfoot Rollers

• Pneumatic Tyred Rollers

• Vibratory Rollers

• Grid Rollers

Smooth Wheel Roller

Smooth Wheel Roller

• One steel drum in Front and Two steel drum in Rear

• Area Coverage (100%)

• Gross weight (8 to 10 tonne)

• Adequate no. of passes (8 passes/20cm layer)

• Appropriate Speed (3 to 6 kmph)

• Contact Pressure (380 kPa Approx.)

• Suitable for compacting Gravels, Sand and Crushed Rock

• Performance depends on load per cm width

• Major Drawback: Non-reversibility of these tractor drawn rollers

Smooth Wheel Roller

Characteristics of 8-Tonne Smooth Wheel Roller

Sheepfoot Roller

Sheepfoot Roller • Many solid round or rectangular feet attached to steel drum

• Area Coverage (8 to 12%)

• Adequate no. of passes (12 to 20 passes)

• Appropriate Speed (6 to 10 kmph)

• Contact Pressure (1400 to 7000 kPa)

• Suitable for compacting heavy clays and silty clays

• Major Drawback: The loose top-lift material can act as a sponge

when it rains and slow the compaction process.

Sheepfoot Roller

General Characteristics of Sheepfoot Roller

Pneumatic Tyred Roller

Pneumatic Tyred Roller • 4 pneumatic smooth wheels on the Front axle whereas 5

wheels on the Rear axle to exert uniform pressure

• Area Coverage (80%)

• Adequate no. of passes (7 to 8 passes)

• Appropriate Speed (1.6 to 24 kmph)

• Contact Pressure (500 to 700 kPa)

• Used for both Earthwork and Bituminous Work

• Major Drawback: When stopped straight creates bulge which may not roll out

Vibratory Roller

Vibratory Roller

• Similar to smooth wheel rollers with the modification of

rotating drums

• Area Coverage (100%)

• Appropriate Speed

For Rock and Clay (1 to 2.5 kmph)

For Gravel and Sand (2 to 5 kmph)

• Very expansive but have high output and performance

Vibratory Roller

Several parameters influence compaction by vibratory roller:

• Frequency

• Amplitude

• Dead Load

• Dynamic Force

• Area of Contact

• Ratio between frame and drum weight

Vibratory Roller • For best compaction results frequency of roller should be

between 1 to 1.5 times the frequencies of soil

• Compaction effect is maximum between frequencies 25

and 50 Hz

Vibratory Roller

Vibratory Rollers have further following types:

• Towed Vibratory Rollers

• Self Propelled Rollers

• Vibratory Tandem Rollers

• Combination Rollers

• Double Drum Rollers

Vibratory Roller

Towed Vibratory Roller

• Weight (4 to 6 tonne)

• Heavy-duty rollers weigh up to 15 tonne so layer

thickness can be increased

• They cannot be reversed resulting into time loss

Vibratory Roller

Self Propelled Rollers

• Steel drum at the front and 2 pneumatic wheels at the rear

• Weight (8 to 12 tonne)

• Weight can be increased by ballasting

• For better performance at high static linear load, the

drum diameter must be large.

Vibratory Roller

Vibratory Tandem Roller

• Weight (7 to 17 tonne)

• Used mostly for bituminous work

Vibratory Roller

Combination Roller

• Vibrating drum on one axle and 3 to 5 pneumatic wheels

on the other axle

• Primarily used in bituminous work

Vibratory Roller

Double Drum Roller

• Useful for compacting soil in restricted areas, trenches etc.

• Improve elimination of internal friction between particles

• Improve pressure and shear stresses

Grid Rollers

Grid Rollers

• A cylindrical heavy steel surface consisting of a network

of steel bars forming a grid with squire holes

• Weight (5.5 to 15 tonne)

• Appropriate Speed (5 to 24 kmph)

• Weight can be increased by ballasting with concrete blocks

• Provide high contact pressure

• Suitable for coarse grained soils

Required Compaction Compaction test on particular soil in laboratory by:

• Standard Proctor Test

• Modified Proctor Test

To obtain compaction curve, OMC and MDD

Field densities are determined by:

• Sand Cone

• Nuclear Density Gauge

Results are compared. For 95% relative compaction, about 70% relative

density is specified.

Required Compaction