Rollers

Rollers (or roller compactors) are pieces of machinery or vehicles used to flatten or compact soil, gravel, concrete or asphalt for construction purposes. Usually driven by diesel, they work by applying the principles of impact loading, vibration, kneading or exerting direct pressure. The efficiency of the vehicles can be increased by ballasting (filling the drum with water or wet sand.) There are a wide variety of rollers. Smaller pieces of machinery, controlled by handles, include rammers, vibrating plate compactors and vibro tampers. A vibratory roller has two smooth wheels or drums at either end of the vehicle plus vibrators. The single drum of the Sheepfoot roller has hexagonal shaped 'feet' on its surface. A tamping roller is similar but has four wheels. A smooth-wheeled roller has a large metal drum and two or three wheels. A pneumatic (or rubber) tyre roller can have four to six wheels. Grid rollers have their drum constructed from steel bars forming a grid with square holes. Rollers are used in the construction industry to prepare the surface of the site for the laying of roads or foundations. The choice of which to use depends on the stage of the construction work plus the moisture level and type of soil.