A. Definition and description
1. Types of roller compactors
Roller compactors’ classification is based on the structure of the drum and the operation mechanism. The two main classifications are vibratory and static. However, based on the structure of the drum, the following types exist.
Smooth roller compactors
This type of roller has a consistent smooth drum surface. It is suitable for compaction of granular material such as sand and gravel.
Padfoot roller compactors
These rollers have protruding squares or oval pads(feet) on the drum. The pads break the material for effective deep compaction. The small area of pads reduces the compaction force to area ration; this increases the pressure exerted on the roil. Padfoot rollers are suitable for both granular and cohesive materials. They require fewer passes to achieve required densities compared to smooth rollers.
Pneumatic roller compactors
These rollers do not have a drum. Compaction is achieved through air-filled rubber tires on which the cabin sits. Pneumatic rollers rely on the engine and cabin weight to exert compaction force. The rubber tires provide a kneading effect when driven over material; hence the roller is used in asphalt paving to provide a smooth finish.
1. Effective for large-scale projects
Roller compactors are engine powered; their operation is less-dependent on human energy. This allows compaction to be carried out for longer periods and at a faster rate. For large-scale projects, roller compactors reduce the compaction time and labor expenses.
2. Wide coverage and even compaction
Roller compactor drums are wide enough to cover significant widths with every pass. This ensures compaction of larger areas within a short time. The even weight distribution on the drum ensures consistent compaction force distribution with every pass. Overlapping passes ensure no area is left uncompacted.
3. Suitable for various soil types
There are various types of road rollers; each can be used for specific conditions. However, some rollers can be used for more than one type of or terrain conditions. Vibratory roller compactors can be used for their intended purpose or used as static rollers when the vibration is turned off.
1. High initial cost
The cost of acquiring a roller compactor is high. Prices depend on many factors and can be affected by slight changes in the market. Additionally, very few distributors are available around the country. This implies that you have to incur transportation costs; which may vary depending on regulations set by governing authorities.
2. Limited maneuverability in tight spaces
Roller compactors are difficult to operate due to their weight and size. They require larger turning spaces compared to other compaction equipment.
3. May require skilled operators
A balance of skill and compaction knowledge is needed to operate a roller compactor. Some compactors have complex technologies for improved efficiency. This leads to a need for operator training or hiring an already trained operator which could be costly.
D. Best Use Cases
1. Road construction
Roads are designed to sustain design traffic loads. Roller compactors are used to improve the density of the base and subbase layers. This prevents settling of material particles which may result in cracking and pothole formation.
2. Highway projects
Besides heavy traffic loads, highways exposed to varied adverse weather conditions. Roller compactors eliminate air pockets from the construction material; prevents rutting during high temperatures. Additionally, smooth and pneumatic rollers are used to provide a smooth and consistent surface to prevent tire damage.
3. Large parking lots
Roller compactors improve the material density and bearing capacity; this ensures the parking lot can sustain the weight of parked vehicles. Additionally, roller compactors ensure and even flat parking lot for easy maneuverability and stability of vehicles.