Construction Equipment useful for Compaction
Compaction equipment is used to increase the density of subbase, base, and pavement materials. By applying weight to a material, the size of the spaces between individual particles will be decreased.
This will result in a higher density for the material, which will make it more stable under a load. There is a wide range of compaction equipment on the market. The type of roller used is usually determined by the type of soil to be compacted and the desired dry density.
In other words, Roller compaction is to provide pressure to the layer as the roller advances, gradually increasing and then decreasing the pressure applied at a place inside the layer. Compression and slight rearrangement of the soil grains cause the loose soil particles to be evacuated.
The modern earth compaction equipment is a self-propelled, rubber-tired construction machine that is used to flatten the ground surface for highways, airports, embankments, and earthen dams, among other things.
The following are some of the different types of soil compaction rollers:
1. STATIC ROLLER
These rollers are also referred to as smooth wheel rollers or single wheel steel wheel rollers. The smooth wheeled rollers are suitable to compact a wide range of soils, particularly found to be useful in compacting soils and other materials in the pavement layers where a little crushing action is permissible. The type of steel-wheel roller to be used depends on the material to be compacted.
There are two types of wheel configurations available for steel-wheel rollers. They are:
- Tandem Roller with two steel wheels of the same width at rear end and
- Self propelled roller has one steel wheel and two rubber tires. or three wheeled roller and is usually vibratory.
The compacting efficiency of the smooth wheeled roller depends on the weight, width and diameter of each roller wheel. Tandem rollers are most often used to compact asphalt pavement, although they can also be used to compact soil and aggregate.
Material can accumulate on the steel wheel’s surface during compaction, resulting in uneven compaction. Scraper bars and sprinkler systems are installed on rollers to avoid this. To avoid inconsistencies in the subbase and base course, make sure this equipment is in good working order.
2. VIBRATORY ROLLER
Compaction is produced in vibratory rollers by both the dynamic effect of the vibratory force and the static weight of the roller. An eccentric loading system on the roller, which can revolve at a high speed, produces vibration.
The amplitude and frequency of vibration in vibratory rollers can be varied within a specified range; the amplitude and frequency are modified depending on the type of material to be compacted.
Vibratory rollers can compact a wide variety of soils, but they’re especially good at compacting granular soils and pavement layers with granular elements like aggregates.
During compaction the soil and aggregate particles can move in all direction under the combined effect of vibration and pressure; thus higher degree of densification can be achieved. Vibrations with a high amplitude and low frequency are required for soils and granular pavement layers.
A wide range of small and medium-capacity vibratory rollers with single or double drums and static weights ranging from 0.5 to 6 tonnes are now available, each with its own set of features and benefits.
There are also small vibratory rollers that need the operator to walk behind the roller to control the turning movements; this sort of small roller is known as a “walk-behind type roller.”
3. SHEEP FOOT ROLLER
Pad foot rollers are another name for these rollers. They’re used to compact fine-grained soils including clays and silts, as well as sand-fine-grained soil mixtures.
The sheep foot roller is a steel wheel that has a number of steel projections, or feet, welded to it. By kneading the earth, the roller compacts it. The roller’s feet can penetrate loose soil to a depth of around 10 inches (250 mm). When the lift thickness is between 6″ and 10″ (150 and 250 mm), these rollers function best.
The smooth surface of the wheel compacts the soil on the surface of the lift, allowing the feet to sink through the loose material and knead it into the lift below. The feet travel up into the higher portions of the lift and compact it when the lower portion becomes compacted.
It is advisable not to compact a lift all the way to the top surface due to the way it is compacted. A better bond will be created between that lift and the next lift that is applied if the surface material is left loose.
Sheep foot rollers, like steel-wheel rollers, can be static or vibratory, and come in a variety of models. Self-propelled, tandem, four-wheel, and towed are the most common models. Furthermore, some sheep foot rollers are equipped with miniature bulldozer-style blades, allowing the roller to do rough grading or backfilling while compacting the soil.
4. PNEUMATIC TIRE ROLLER
Rollers with pneumatic tyres, often known as rubber tyres, can compact almost any type of soil. Bituminous pavement is also compacted with these rollers. Pneumatic-tire rollers, on the other hand, are ineffective for compacting aggregate.
The tyres of pneumatic-tire rollers are arranged in two rows. Although a roller will only have one size of tyre, the tyres can be small or large. There are an odd number of tyres, and the back row is offset from the front row such that the two rows’ combined effort compacts the soil across the whole width of the roller.
Rollers made on pneumatic tyres are exclusively static. They work by kneading and applying static pressure. Because of the number of tyres on a pneumatic-tire roller, the equipment might take on a lot of extra weight. The overall static compactive force is increased as a result.
However, too much weight can cause the soil particles to break down into sizes smaller than those required by the specifications. As a result, the weight of the pneumatic-tire rollers should be checked to ensure that the final base course meets the requirements.
Because the air pressure in the tyres may be regulated, pneumatic-tire rollers are useful. While the roller is operating on numerous machines, the pressure can be changed separately for each tyre. Lower tyre pressure reduces compactive force while allowing more of the tyre to make contact with the ground. A higher tyre pressure on the ground will exert a greater force across a smaller area.
As a result, the first passes of the roller are frequently made with low tyre pressure to ensure that the entire lift is compacted. Then, for the final passes, a high tyre pressure might be used to achieve the required density.
Because of the variation in compactive effort, the required compaction may usually be achieved in fewer passes than with another type of roller.
5. MANUALLY OPERATED COMPACTORS
Compactors that are operated by hand have a variety of uses. They’re utilized in locations where a full-size compactor isn’t feasible. This includes tasks like compacting fill over a trench, compacting soil around a footing, and working in regions where huge machinery could damage nearby structures or property.
Depending on the purpose, manual compactors are available in a variety of styles. Small steel-wheel rollers, vibratory plate compactors, and rammers are all available. While these smaller compactors allows to work in small areas, they require more time and effort to compact the material to the required density. Wherever possible, it is preferable to use full-size equipment.
In Conclusion, Unless the Specifications require a certain type of compactor, the choice of compaction equipment is left based on the type of material to be compacted.
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