Different dynamic compaction methods in comparison. Circular exciter – directed exciter - and oscillation systems

Basically, four different compaction systems for asphalt are offered to the market:

Static Rollers with steel drums or rubber tiered wheels,

Rollers with circular exciter systems,

Rollers with directed exciter systems, and

Rollers with oscillation systems.

From various manufacturers, you will also get a system mix. For example, circular plus oscillation system or circular exciter drum and rubber tired wheels.

All these systems in the market have their qualification and are well proven and tested by hundreds of contractors.

Here is a short description of the different principles and their differences in practice.

Compaction systems

Dynamic compaction systems improve the compaction performance of a roller, significantly. These systems are stimulating the surface by vibrations in such a way that the relocation of the aggregates into closer position can take place. With vibration, the material is set into vibration by forces in fast implications.

Circular exciter

One example for a roller with circular exciter systems:

Atlas Copco CC 2200 with circular exciter system www.atlascopco.us

http://www.hamm.eu/en/technologies/oscillation/

Circular exciter is a very simple method to create vibration. A weight that is attached eccentric to a shaft is rotating. By fast rotation, the drum begins to vibrate; thereby compaction forces arrive into the material to compact. In most cases, two amplitudes and two rotation speeds are offered.

Directed vibration

One example for a roller with directed exciter system:

BOMAG BW 161 AD www.bomag.com

http://www.hamm.eu/en/technologies/oscillation/

Directed vibration is created by the same principle as circular, but two eccentric weights are usually connected to each other by a gear. The eccentric weights are rotating in opposite directions to create directed vibration. The direction of the vibration and the height of the amplitude can be changed infinitely between zero and maximum, by rotating the eccentric weights in regards to a vertical line. The impact angle of the force changes between vertical and horizontal.

Oscillation

One example for a roller with oscillating exciter system:

Hamm HD 80 www.wirtgen-group.com

http://www.hamm.eu/en/technologies/oscillation/

Oscillation is created by the same principle as circular vibration; two eccentric weights are used and connected to each other by a belt. The eccentric weights are rotating in the same direction to create an oscillation movement of the drum and produce a moment around the drum axle. The moment changes its effect direction during a cycle of the mass (forward and backward) so that the oscillation drum movement is created. Thrusts, which are introduced into the material, generate the movement of gravel and soil. Oscillation rollers are particularly demanded for bridges and areas where vibration could cause damage on buildings and other objects. It allows high compaction performance and produces no damaging vibrations.

Summary

Roller with circular exciter systems are the most versatile compaction system compared to directed vibration and oscillation. Depending on the application, each of these systems has their strength and weaknesses. The best information for your application you will receive from contractors whom utilize the various systems for years and are not linked to a certain manufacturer.

The easier a roller is to use the better the compaction results will be, because errors in machine handling will cause the biggest possible damage. Keep in mind: A roller has more than one operator!