Floating is an essential
step in finishing a concrete floor. It leaves the floor with a layer of fat
above the aggregate, which is essential for other finishes, such as a trowelled
or textured finish.
It is important to time
floating correctly. A simple and effective indicator of whether it is time to
float the concrete is how deep an imprint is left by a boot’s heel. If the
imprint is more than a few mm deep, the concrete is not yet ready to be floated
and if the heel leaves no imprint, it is too late for floating to be effective.
Mis-timing floating could
have the following consequences for the slab surface:
- If a slab is floated
before bleeding has finished, there is an increased risk of delamination.
- If the slab is
floated whilst the concrete is still too soft, the surface can be torn up.
- If the slab has
hardened too much before floating begins, the floating will be ineffective and
the surface imperfections will remain.
The following equipment can
be used to float a concrete floor slab:
Power float –
A power trowel fitted with float blades or a pan. The best way to float large
Bull float –
A T-shaped handheld tool consisting of a long handle and a float blade (up to
3m in width).
Hand float –
A float blade with a handle on the back. Suitable for small areas and for
places that can’t be reached by a power float in larger projects, such as panel
Too much power floating can lead to a darkening of the surface of the
slab, known as burnishing.