A power trowel is used to create a smooth finish on a large, flat area of concrete, such as an interior floor, or a poured patio slab for a deck.
They use multiple blades that rotate in a safety cage.
- Have the concrete poured a few hours before using the power trowel. Make sure it is firm enough to support you and the power trowel by doing a footprint test; step onto the slab and measure the imprint depth. If the imprint is 3mm deep or less, the concrete is ready for troweling.
- Use the trowel with float blades to level the concrete on your first pass. Floating reduces bumps (hills) and fills in the hollows (valleys).
- Run the machine at 3/4 speed with the blades flat to keep the weight of the machine evenly distributed and avoid digging into the concrete. This speed of rotation will also prevent splatters of still-damp concrete from being thrown forward into the machine's path. Overlap each pass by 1/2 the length of the trowel blades as you traverse the poured plate.
- When you finish floating the entire slab once, turn the power trowel at 90 degrees to your first rows. This crossover floating technique enables you to finish missed spots.
- Then run the power trowel at its top speed this time with the blades fully pitched downward onto the concrete. This will give the highest pressure on the slab. Make as many passes at right angles as desired to get a matte, light gloss, or gleaming finish.
- When operating the power trowel, reduce speed when turning corners to avoid tipping the machine. Also, cordon off the area, for safety and to prevent marring the concrete.