Professional Tools for UK Sites

The sequence, and where each machine fits

Concrete work runs in an order, and each machine belongs to one stage. Buying out of sequence is how a pour ends up with the right tools for the wrong moment.

1. Mix and place. Cement mixers, petrol or electric.
2. Compact. Poker vibrators drive out entrapped air.
3. Level. Screeders and hand tampers strike the surface to level.
4. Finish. Power trowels close and harden the surface.

Skip the vibration stage and you get honeycombing and exposed reinforcement. Skip the finishing stage and you get a surface that dusts.

Poker vibrators

A poker removes air voids so the concrete is dense and fully surrounds the reinforcement. It does this by liquefying the mix locally for a few seconds.

Insert it vertically at regular spacings, leave it until the surface around it stops releasing bubbles, then withdraw it slowly enough that the concrete closes behind it. Two mistakes are common: using the poker to push concrete sideways along the shutter, which separates the aggregate from the paste, and over-vibrating in one spot, which brings a layer of laitance to the surface.

Poker diameter should suit the section and the reinforcement spacing. A large poker cannot get between close bars; a small one will not compact a deep section.

Screeders and tampers

A vibrating screeder rides on the forms or rails and levels and compacts the top surface in one pass. Beam length must match the pour width, which is why the beams here come in separate lengths from 1.2m to 4.8m and can be bought without the drive unit.

Hand tampers do the same on smaller pours and around obstructions where a beam cannot reach. Most jobs need both.

Power trowels, and timing

A power trowel closes and densifies the surface. It is the one machine in the sequence where the timing is more important than the technique.

Go on too early and the machine sinks in and ruins the level. Leave it too late and the surface has gone off beyond the point where it can be closed. The window is once the bleed water has gone and the slab supports the machine with only a slight impression.

Float pans go on first to flatten and open the surface; combination blades work through the middle stages; finishing blades close it at the end. Pan and blade sizes here match 24", 36" and 46" machines, so check the machine size before ordering consumables.

For compacting the ground beneath, see compaction equipment.