Power Trowels

Summary

Power Trowels - are used to apply a smooth, durable finish to the exposed surface of concrete slabs. There are two main types of power trowel; walk-behind and ride-on.

Technical Information

The working mechanism of a power trowel consists of flat blades which are turned in a circular motion by a motor. It is for this reason that they are sometimes referred to as helicopters.
A concrete floor is initially floated before trowelling. Float blades or a pan can be attached to a power trowel in order to float the concrete surface.

Finishing blades are attached to the power trowel in order to trowel the concrete. During the trowelling process, and multiple passes are made over the floor. The blades are almost flat on the first pass and are inclined more and more between each pass. This makes them exert more pressure on the surface as it stiffens.

It is important to not power trowel a concrete floor until the slab has mostly finished bleeding as this increases the likelihood of delamination. Also, the concrete must have reached the correct stiffness when power trowelling commences. If it is too soft, the blades will tear up the surface. If it is too stiff, the blades will have little effect.

Power trowelling of air entrained concrete is not recommended as it carries a high risk of delamination.

Crazing is a defect which can be caused by power trowelling. It is a purely cosmetic defect and has no structural effect. Too much power floating can lead to a darkening of the surface (burnishing) and aggregate shadowing.