What is power floating?
Power floating is the finishing of a concrete floor while the concrete is setting, at the moment the slab can just be walked on. In Dutch it is called vlinderen, from vlinder (butterfly), after the butterfly-like pattern the machine leaves on the floor. The work is done with a power float or power trowel: a machine with rotating blades under a guard ring. The full process is also known as power trowelling.
How does it work?
- Floating: float pans or float blades first open up the top layer of the concrete.
- Dry shake (optional): a hard-wearing material can be scattered over the opened surface and worked into the top layer of the concrete with the machine.
- Letting it stiffen: the slab must stiffen again until the texture becomes finer, after which it is floated again.
- Trowelling: once the texture is fine, the floating blades are replaced by finishing blades. For a very smooth surface you repeat the passes until the top is smooth and closed.
Floating pushes the coarser particles down and brings the fines to the surface. The slab and its top layer form one whole, which is why this is also called a monolithic finish.
Application
Power floating is used for industrial floors, garages, warehouses and, increasingly, homes with an exposed concrete floor, sometimes finished with a coating. There are small walk-behind machines and large ride-on machines for one or two operators. Many power trowels run on petrol, so that no cables trail across the fresh surface.
Tips
- Timing is everything: only start when you can walk on the slab without leaving deep footprints. Too early gives ripples; too late and you can no longer close the surface.
- Edges and corners: finish areas the machine cannot reach with a hand trowel.
- Curing: protect the floor from drying out afterwards, or shrinkage cracks will form in the hard surface.
- Plan the joints: decide in good time where contraction joints will be sawn.
- Hiring a machine: there are many types and sizes. Choose a size that suits the area and practise on a less visible part first.
Related terms
- Concrete floor
- Trowel
- Wear layer
- Monolith
- Concrete curing
- Contraction joint
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