The concrete vibrator is used to eliminate air pockets and bubbles that prevent aggregates from properly clustering. Thus, the concrete is vibrated to achieve a smooth and uniform appearance after formwork removal.
The vibrating needle has several characteristics to know:
- it has a cylindrical shape with a conic or hemispherical end for easy penetration into the concrete;
- it is waterproof;
- an off-center weight located in the cylinder produces vibrations by spinning rapidly;
- the frequency varies from 3,000 to 20,000 vibrations per minute (v/min);
- models with a diameter ranging from 25 mm to 60 mm are intended for vibrating a quantity of less than 10 m³ of concrete at 20,000 v/min;
- models from 60 mm to 100 mm in diameter are suitable for projects over 10 m³ with a frequency of 10,000 v/min.
Vibrating needles differ by their motorization.
- Electric models are connected to an electronic converter. They operate under 220 V. The motor power varies from 800 W to 3,000W. The diameter of the vibrating needle ranges from 25 mm to 65 mm and can operate at a frequency between 10,000 v/min and 140,000 v/min. This type of device is suitable for small projects with a yield lower than 8 m³/h.
- Pneumatic models require the use of a compressor. They are suitable for large construction sites. The vibration frequency ranges from 8,000 to 20,000 v/min.
- Models with a thermal engine are also called poker vibrators. They are usable in areas without electric power.
Vibrating screeds are also available for vibrating surfaces.
- Electric models consist of an aluminum blade 1.5 m to 3 m long on which a mini electric motor of 700 to 900 W is mounted. A tiller allows the user to easily steer the rod. The blade can be replaced if necessary.
- Thermal models are equipped with a mini gasoline or diesel engine with a power of 1,000 W. They are intended for extended use (more than 6 consecutive hours).
If vibrating a formwork concrete is essential to obtain an optimal result, the choice of vibrator depends on the quantity to be treated and the available power source.
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