written by: Finn Orfano
• edited by: Lamar Stonecypher
• updated: 1/12/2010
A variety of equipment is used for soil compaction. A road roller is one of the main items of equipment in this category that is used extensively for road construction. A road grader is also used in combination with the road roller for soil leveling.
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When is Soil Compaction Required?
There are numerous requirements where it is essential to produce a level and equally compacted ground surface. Generally, soil compaction is required for the improvement of the subsurface and the surface finish of a road. Consistency in compaction and the surface smoothness are particularly important for roads that are to be used for heavy traffic. Non-uniform and improper compaction may create irregular and extensive surface wear. A soil moisture content analysis would be essential prior to the road construction. An irregular road surface produced due to uneven wear or by insufficient smoothing will cause fast deterioration of the road surface. Normally, a road is constructed with the foundation consisting of comparatively larger stones. The intermediary layer consists of the binder and small stones, and the surface layer consists of bituminous substances. As each of the layers is positioned, it is compacted and flattened by a road grader and a road roller. Safety on road construction work is of utmost importance to prevent accidents.
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Road Roller Functions
Basically, the roller drum weight is used for the compression of the surface required to be compacted. The initial compaction is obtained by the use of roller with tires. The wheels are flexible to attain some vertical movement that enables the roller to operate efficiently on an irregular ground surface. Subsequently, the final road surface finish is obtained by the use of rollers with metal drums. Road rollers are also used for the compaction of landfills. Such rollers have knobbed wheels and are used when a perfectly smooth surface is not required.
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Road Roller Components
Road rollers consist of two or more big heavy drums, with one drum being driven and provide the pushing force. The other drum is pivoted, and connected to the roller body. It is rotated to guide the roller to the chosen pathway. In some rollers, the drum axles move in relation to each other to adjust for the surface irregularities. Different compacting and smoothening equipment is used with rollers for road construction operations. Normally, a road roller consists of roller units at the front and rear, with a hydraulic steering system. On some equipment, the roller drums are water filled to attain the weight desired for compaction of the road surface. Compaction can be increased by using vibrating roller drums that enables a smaller machine to achieve the same compactness as by a larger roller. Vibration is normally obtained by eccentric weights that are attached to the shaft of a motor located in the roller drum. The drum surface is lubricated by water for the prevention of asphalt being affixed with the drum surface. The other parts of a roller are a diesel engine, a driver canopy, a compaction gauge to determine the intensity of compaction, and a water supply system.
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Types of Road Rollers
The roller kind that is suitable for a particular application is generally dependent on the nature of construction materials being utilized, the soil conditions, the moisture content, and the weight required to achieve the desired compaction. The road roller should ensure that the foundations are properly compacted so that the materials do not become loose. The road rollers generally used are the static weight rollers that have an even steel cylinder, with a single axle. Compaction is achieved by forcing the soil upwards in the movement path. Other kind normally used is the three wheel roller that is suitable for compaction of bituminous materials in fine layers. It has a large roller at the front and two small rollers at the rear. The front drum is steered, while the rear rollers are driven. It is useful due to its capability to manage considerable surface areas.