A power float is a hand-operated machine used to produce a smooth, dense and level surface finish to insitu concrete beds. Power floating eliminates the time and materials needed to apply a finishing screed and is quicker and less labour-intensive process than hand trowelling.
Power floats have an electric motor or petrol engine fixed over a circular pan or skimmer which smooths concrete before hardened steel reversible metal blades rotate at up to 150 rpm over the surface to create a hardened finish.
Before power floating the concrete must be left to partially set, having been leveled and tamped. The amount of setting time necessary before power floating will depend on variables such as; air temperature, humidity, the specification of the mix and so on. A rough guide for considering when to begin power floating is when walking on the surface leaves indentations of 3-4 mm. If the concrete is too wet the machine will tear up the surface, and if it is too dry, it will not be possible to trim high spots or fill low spots effectively.
Floating usually starts at one end of the slab and moves to the other. The operator holds the float at waist-height and moves backwards so that the float removes their footprints. The speed should be slow and consistent.
Once the surface has been floated, the blades are angled to suit the concrete and achieve the specified finish. Blade angles of around 5-10 degrees are usual, but these may need to be increased after each pass over the surface.
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 External references
- Speedcrete - Power floating tips
- ‘Building Construction Handbook’ (6th ed.), CHUDLEY, R., GREENO, R., Butterworth-Heinemann (2007)
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