Troweling cement is a key process for achieving a smooth, level, and durable surface on concrete. A crucial early step in this process, often done with a float before final troweling, involves smoothing and compacting the surface to prepare it.
The Role of Floating in Cement Finishing
After the concrete has been placed and screeded (leveled), the next step in achieving a finished surface is often floating. Floating helps to consolidate the surface, smooth out screed marks, and bring "fat" (a mixture of cement paste and fine aggregates) to the top. This prepares the concrete for subsequent finishing steps, like final troweling.
Step-by-Step: Floating the Cement Surface
Floating the concrete surface is performed once the water sheen has disappeared but while the concrete is still plastic enough to work.
Here's how to execute this important step, incorporating the technique described in the reference:
- Get into Position: Kneel on a board or use knee pads to avoid disturbing the wet concrete.
- Hold the Float: Hold the float's handle and gently press it into the concrete. Floats can be made of wood, magnesium, or other materials. Magnesium is often preferred for initial floating as it opens the surface slightly, while wood closes it more.
- Perform the Motion: Move the float in a circular or figure-eight motion to smooth and level the surface. This continuous motion is essential for effective floating.
- Understand the Purpose: This motion will help push down any larger pieces and fills in small voids. It brings the fine material to the surface, creating a workable paste.
- Cover the Area: Continue floating the entire surface, working from one end to the other. Ensure consistent pressure and coverage across the slab. Over-floating should be avoided as it can draw up too much fine material or water, weakening the surface.
| Floating Tool Type | Primary Material | Common Use | Surface Result |
|---|---|---|---|
| Hand Float | Magnesium, Wood | Initial smoothing, embedding aggregate | Slightly open/closed |
| Bull Float | Magnesium, Wood | Large area initial smoothing after screeding | Initial level/smooth |
Floating is typically followed by waiting for the concrete to stiffen further before performing final troweling with a steel trowel, which creates a hard, dense, and smooth finish.
Why is Floating Important?
Floating serves several critical functions:
- It eliminates minor irregularities left by the screeding process.
- It embeds larger aggregate particles just below the surface.
- It brings a layer of paste to the surface, which is necessary for subsequent finishing operations like troweling or brooming.
- It compacts the surface layer, improving its density.
Mastering the technique of floating, as described above, is a fundamental step in achieving a high-quality concrete finish.
