How long should a concrete vibrator stay in?

Five to fifteen seconds per insertion. A sheen of cement paste at the surface and air bubbles stopping are the signs.

Which poker diameter should I choose?

By section and rebar spacing: 25-35 mm for thin, densely reinforced sections, 50 mm for general wall and slab work, 60-70 mm for foundations and thick sections.

What is radius of action?

The distance around the poker over which vibration is effective, roughly 8-10 times its diameter — about 40-50 cm for a 50 mm poker. Insertions should be no further apart than 1.5 times that radius.

Can over-vibration cause damage?

Yes. It segregates the mix: coarse aggregate sinks, paste collects at the surface and the concrete loses its uniformity.

What does built-in converter mean?

The frequency converter is inside the poker, so nothing separate has to be carried and the set plugs straight into the mains. On backpack models the motor rides on the operator's back and drives a flexible shaft.

Why would a vibrator hose need replacing?

The hose carries the flexible drive and its outer casing, and it is a wear part. Loss of flexibility, heat and shaft wear are the signs; spare hoses are listed in the same range.

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Concrete Vibrators

A concrete vibrator drives the air voids out of fresh concrete with high-frequency vibration so it fills the formwork and surrounds the reinforcement. Under-vibrated concrete loses strength outright; over-vibrated concrete segregates. The range here covers backpack and built-in-converter models, plus spare hoses.

Poker diameter and radius of action

Poker diameter sets both the area it works and the sections it can enter. The radius of action is roughly 8-10 times the diameter: a 50 mm poker covers about 40-50 cm, a 70 mm poker 55-70 cm.

Thin, heavily reinforced sections need a small poker — one that cannot pass between the bars cannot vibrate the concrete. In wide foundations and thick walls a large poker covers the same area with fewer insertions.

Poker diameter	Radius of action (approx.)	Suits
25-35 mm	20-35 cm	Thin sections, dense rebar, columns
50 mm	40-50 cm	Walls, slabs, general use
60-70 mm	50-70 cm	Foundations, thick walls, wide sections

Correct technique

Insert the poker vertically and quickly, hold for 5-15 seconds, then withdraw slowly — about 8 cm per second. Keep insertion points no further apart than 1.5 times the radius of action.

A sheen of paste at the surface and bubbles stopping mean the concrete is vibrated enough.
Over-vibration segregates the mix: coarse aggregate sinks.
Never use the poker to move concrete horizontally — that separates it.
When placing a new layer, the poker should enter 10-15 cm into the layer below to knit them together.
Avoid resting the poker against reinforcement or formwork.

Backpack or built-in converter?

On backpack models the motor is carried on the back and drives the poker through a flexible shaft, which gives freedom of movement on site. On built-in-converter models the frequency converter sits inside the poker: nothing separate to carry, and the set plugs straight into the mains.

Frequently Asked Questions

How long should a concrete vibrator stay in?
Five to fifteen seconds per insertion. A sheen of cement paste at the surface and air bubbles stopping are the signs.
Which poker diameter should I choose?
By section and rebar spacing: 25-35 mm for thin, densely reinforced sections, 50 mm for general wall and slab work, 60-70 mm for foundations and thick sections.
What is radius of action?
The distance around the poker over which vibration is effective, roughly 8-10 times its diameter — about 40-50 cm for a 50 mm poker. Insertions should be no further apart than 1.5 times that radius.
Can over-vibration cause damage?
Yes. It segregates the mix: coarse aggregate sinks, paste collects at the surface and the concrete loses its uniformity.
What does built-in converter mean?
The frequency converter is inside the poker, so nothing separate has to be carried and the set plugs straight into the mains. On backpack models the motor rides on the operator's back and drives a flexible shaft.
Why would a vibrator hose need replacing?
The hose carries the flexible drive and its outer casing, and it is a wear part. Loss of flexibility, heat and shaft wear are the signs; spare hoses are listed in the same range.