Concrete vibrator machines come in various types, each serving specific purposes in construction. The primary function of concrete vibrator machines is to ensure proper compaction, eliminating air voids and enhancing the overall strength and durability of the concrete structure. Choosing the right type depends on the specific requirements of the construction project.
Concrete vibrator is mechanical machine comes in various shape and size and it has different needle like 25 mm to 90 mm for pouring of fresh concrete. Different types of concrete vibrators machine are used in concrete compaction for different construction and structural requirements. Concrete vibrator machine is used for removing air void from concrete mass and prevent from formation of honeycomb.
Since concrete contains particles of different sizes fine aggregate and coarse aggregate, the most effective compaction of concrete can be achieved by using vibrators with different speeds of vibration.
Poly-frequency concrete vibrators machine is used for compacting concrete mass of stiff consistency are being developed. The vibrators machine for compacting concrete are manufactured with frequencies of vibration from 2800 to 15000 rpm.
What is a Concrete Vibrator machine?
Concrete vibrator is mechanical device is used to compaction of fresh mass concrete. A concrete vibrator is a machine used for construction-based purposes. These vibrator machines can come in several different shapes and sizes.
Some are small and run strictly on battery power, some on diesel or petrol while others are much larger with a primary power source stemming from electric power cords. Choosing the right concrete vibrator can help settle your concrete for long-term stability and maintenance.
Why we use a Concrete Vibrator machine?
Concrete vibrator machine used to remove air avoid present between the concrete ingredients and prevent from concrete forming honeycomb. Using vibration to assist concrete during its settling period has proven a worthwhile method that aids in long-term durability. As wet concrete is poured, air bubbles become trapped within the mixture creating cavities or honeycomb-like spaces.
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Left untouched, “honeycombing” can compromise the cement’s longevity and strength. Vibrators force the trapped air out of the mixture leaving the final product a more compact and level slab. It is not uncommon to see small bursts of air surfacing from the wet mixture when the vibrator is being used correctly
Concrete Vibrators machine types
1) internal or Immersion or needle vibrator
2) External vibrator machine
3) Surface Vibrator machine
4) Vibrating table machine
Internal or immersion or Needle Vibrators
Immersion or needle concrete vibrators are known as internal vibrator machine mostly used as construction site.
Immersion or Needle Vibrators are most commonly used vibrator for concrete. It consists of a steel tube (with one end closed and rounded) having an eccentric vibrating element inside it.
This steel tube called poker so also called as Poker vibrator machine is connected to an electric motor or a diesel engine or petrol engine through a flexible tube. They are available in size varying from 40 to 100 mm diameter. The diameter of the poker is decided from the consideration of the spacing between the reinforcing bars in the form-work.
The size of needle of internal vibrator machine is ranging between 25 mm to 90 mm in which for casting of roof slab we should use minimum 25mm needle of vibrator machine and maximum 35 mm. And for column and beam structure we should use 40 mm and 60 mm needle of vibrator machine for the compaction of concrete mass
And when we made a project of a strong footing and several Bridge structure we should use 75 mm and 90 mm needle of vibrator machine for compaction of concrete mass by trapping air voids and prevent from honeycomb.
The frequency of vibration from vibrator machine varies up to 15000 rpm. However a range between 3000 to 6000 rpm is suggested as a desirable minimum with an acceleration of 4g to 10g.
We should use only 5 to 10 second vibrator machine for compaction of concrete mass in case of roof casting of slab and around 15 second in casting of column and beam structure. more than 15 second time of vibration leads to segregation and weaken the bond between concrete ingredient, in which coarse aggregate size settle in bottom and find aggregate size in upper portion of concrete mass that weaken the bond between two and that is pooring of concrete mass.
The normal radius of action of an immersion vibrator is 0.50 to 1.0m. However, it would be preferable to immerse the vibrator into concrete at intervals of not more than 600mm or 8 to 10 times the diameter of the poker.
The period of vibration required may be of the order of 5 seconds to 15 second. The concrete should be placed in layers not more than 1500 mm high.
External or Shutter Vibrators machine
These vibrators machine are clamped rigidly to the form work at the pre-determined points so that the form and concrete are vibrated. They consume more power for a given compaction effect than internal vibrators.
These vibrators can compact upto 450mm from the face but have to be moved from one place to another as concrete progresses. These vibrators operate at a frequency of 3000 to 9000 rpm at an acceleration of 4g.
The external vibrators are more often used for pre-casting of thin in-situ sections of such shape and thickness as can not be compacted by internal vibrators.
Surface Vibrators for Concrete
These are placed directly on the concrete mass. These best suited for compaction of shallow elements and should not be used when the depth of concrete to be vibrated is more than 250 mm.
Very dry mixes can be most effectively compacted with surface vibrators. The surface vibrators commonly used are pan vibrators and vibrating screeds.
The main application of this type of vibrator is in the compaction of small slabs, not exceeding 150 mm in thickness, and patching and repair work of pavement slabs. The operating frequency is about 4000 rpm at an acceleration of 4g to 9g.
Concrete Vibrating Table
Concrete vibrating table is used for concrete compaction on practical site in Laboratories. The vibrating table machine consists of a rigidly built steel platform mounted on flexible springs and is driven by an electric motor. The normal frequency of vibration is 4000 rpm at an acceleration of 4g to 7g.
The vibrating tables are very efficient and easy in compacting stiff and harsh concrete mixes required for manufacture of precast elements in the factories and test specimens in laboratories.