Mumbai University > Civil Engineering > Sem 8 > Construction Engineering

Marks: 10Marks

There are different types of rollers and other soil compaction equipments available. Use of these compacting machines depends on soil types and moisture conditions. The soil compaction equipments can be divided into two groups:

Light soil compacting equipments: These equipment are used for soil compacting of small areas only and where the compacting effort needed is less. Below are light equipments for soil compaction:

Rammers: Rammers are used for compacting small areas by providing impact load to the soil. Rammers are suitable for compacting cohesive soils as well as other soils.

Vibrating Plate Compactors: Vibrating plate compactors are used for compaction of coarse soils with 4 to 8% fines. These equipments are used for small areas.

Vibro Tampers: Vibro tampers is used for compaction of small areas in confined space. This machine is suitable for compaction of all types of soil by vibrations set up in a base plate through a spring activated by an engine driven reciprocating mechanism. They are usually manually guided and weigh between 50 and 100 kg (100 to 220 lbs).

Heavy soil compacting equipments: These compacting machines are used for large areas for use on different types of soils. The heavy compaction equipments are selected based on moisture content of soil and types of soil. Following are different types of these equipments:

Smooth Wheeled Rollers: Smooth wheeled rollers are of two types:

1.Static smooth wheeled rollers: The most suitable soils for these roller type are well graded sand, gravel, crushed rock, asphalt etc. where crushing is required. These are used on soils which do not require great pressure for compaction. These rollers are generally used for finishing the upper surface of the soil. These rollers are not used for compaction of uniform sands.

2.Vibrating smooth wheeled rollers: these rollers are expensive but in the long term the cost becomes economical due to their higher outputs and improved performance. The latest work specifications for excavation recommends the use of vibratory rollers due to their advantage over static smooth wheeled rollers.

Sheep foot Roller: Sheep foot rollers are used for compacting fine grained soils such as heavy clays and silty clays. Sheep foot rollers are used for compaction of soils in dams, embankments, subgrade layers in pavements and rail road construction projects.

Pneumatic Tyred Rollers: These roller are used for compaction of coarse grained soils with some fines. These rollers are least suitable for uniform coarse soils and rocks. Generally pneumatic tyred rollers are used in pavement subgrade works both earthwork and bituminous works.

Grid Rollers: Grid rollers are used for compaction of weathered rocks, well graded coarse soils. These rollers are not suitable for clayey soils, silty clays and uniform soils. The main uses of these rollers are in subgrade and sub-base in road constructions.