Soil compaction refers to the process used to increase the density of soil. It is one of the most important steps in building or road constructions. As it provides a leveled ground, a dense soil and a strong base which are required to support any structures. Generally, the operation of compacting is performed through two methods. Either by vibration or by high pressure using the weight of the machine to compact the soil. Many sectors including agriculture, road construction, building construction, need roller machines at some points. But can we use the same roller for all type of soil compaction? How many types of rollers are there? Depending on the projects, several rollers exist nowadays. Here are 5 important types of rollers generally used in soil compaction.
1.Vibratory Roller Compactor
As the name implies, a vibratory roller compactor is a heavy equipment consists of two smooth wheels used to compact soil, asphalt and many other materials. The two wheels may be either a combination of one drum (horizontal cylinder) and one pneumatic tire or two drums combined. During the compaction process, the vibrator roller compactor provides vibration on the rear or at the front of the roller machine through the drum. Also called self-propelled vibratory roller, these types of rollers come in various capacity nowadays ranging from 1 to 22 tons, even more. They are very powerful but expensive.
How does a vibratory roller work?
Usually, a vibratory roller compactor works through the application of two forces combined. The weight and a circular vibrator at the interface of the drum and the material being compacted. It is quite a recent technological innovation in compaction.
2. Grid Roller Compactor
Generally, a grid roller compactor consists of a cylindrical and strong steel surface composed of a grid with square holes. The use of these types of rollers mainly depends on soil types and moisture conditions. And grid rollers are suitable to compact weathered rocks and soils that contain particles of a wide range of sizes. They are very efficient in crushing oversized material in gravels. However, they are not ideal for some categories of soils including uniform, silty clays and clayey soils as they will not perform well. So they work perfectly in subgrade and sub-base road projects. Not like other rollers, a grid roller compactor can easily adapt to the soil’s bearing capacity and extricate itself.
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3. Rubber Tired Rollers or Pneumatic Roller Compactor
Pneumatic roller compactor or rubber-tired roller is among the types of rollers used in many compaction jobs. They possess an arrangement of multiple tires on both axles which provide a uniform pressure throughout the width of the compactor. There are typically 9 in total with five on one axle and four on the other. That is why the type of compaction, a pneumatic roller compactor achieves, is completely different from other rollers. The quality of compaction varies depending on the weighing, the pressure of the tires which ranges from 500 – 700Kpa. and the area of contact.
What is a pneumatic roller used for?
A pneumatic roller is a type of machinery used for fine-grained and non-cohesive soil compaction during road, dam, and building construction projects. They are also suitable for compacting bitumen layer on highways, or streets during construction work. Also known as rubber tired rollers, they are usually employed to finish uncompleted compaction.
4. Pad Foot Roller or Sheepsfoot Roller Compactor
Unique in its shapes, sheepsfoot roller compactors consist of steel drums with several small rectangular feet which are fixed in a hexagonal pattern. The pressure of such drum can go up to 14kg/sq cm even more. One method used to increase the weight of the sheepsfoot roller compactor also called pad foot roller is by ballasting with water or wet sand. The volume of soil that can be compacted depends on three factors which are: the number of lugs per drum, the size of each lug and the roller’s weight.
What is the purpose of a sheepsfoot roller compactor?
Sheepsfoot rollers are ideally used for compacting fine-grained soil such as heavy clays and silty clays. These rollers are also suitable to compact gravel and asphalt in order to make a smooth foundation.
5. Smooth wheeled Rollers
Like vibratory rollers, smooth wheel rollers are compaction machines but without vibrating system attached on the drums. Which make them smooth as the name implies. These type of rollers are perfect to compact weak aggregates, stone, gravel, hardcore, and ballast. However, smooth wheel rollers are not a good choice for embankments, soft subgrades or uniform sands compaction. Because of the empty voids in the sand, that cannot be compacted without vibrators.
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