1.5. Readiness of Concrete for Finishing

So, there are also machines to do the finishing job. We call them as power floats or power trowels. So, you can see here, it looks like a spider. That is why it is also called a spider. Basically, there are rotating blades inside which help you to finish the concrete surface. The same machine can be used for both floating as well as troweling.

Power floats and trowels are machines designed to finish the surface of concrete. They have rotating blades that provide an efficient way to smooth out and give texture to freshly poured concrete. These machines can serve dual purposes: for floating, which involves a flat blade to smooth out the surface, and for troweling, which requires a slightly angled blade to exert more pressure on the concrete.

Think of a power trowel as a giant kitchen spatula. Just as you might use a spatula to flatten or smooth out a layer of batter in a cake pan, power floats and trowels are used to create the desired finish on concrete surfaces.

When you compare the productivity of manual finishing with simple tools, you can see that manual finishing maximum productivity is 60 square meters per day. But with a power float and trowels, you can go even up to 140 square meters per day. This indicates that using power trowels and floats greatly enhances productivity.

Manual finishing of concrete allows for a maximum output of about 60 square meters per day when done with basic tools. In contrast, the use of power trowels and floats can significantly increase the productivity level, allowing workers to finish up to 140 square meters in the same amount of time. This highlights the efficiency and capability of mechanized equipment compared to traditional hand tools.

Imagine painting a wall by hand versus using a paint roller. While you might be able to cover a small area efficiently by hand, a paint roller allows you to cover a much larger area in less time. Similarly, power trowels expedite the finishing process for concrete, thus saving time and effort.

The guidelines to keep in mind include that the window of the finishing period is between the initial set and final set. The concrete should have dried up well and be free of bleed water. Prior to power floating, the concrete must be able to withstand the weight of the machine.

Before finishing concrete, it is crucial to ensure that it is adequately set, meaning it should have moved beyond its initial to final set phase. The concrete must not only be free of bleed water (the water that rises to the surface during setting) but must also have hardened sufficiently to support the weight of the finishing machines.

Consider baking a cake: if you try to frost it before it has cooled down completely, the frosting will melt and ruin the cake. Similarly, if you finish concrete too soon, before it has set properly, you risk damaging the surface.

To check if the concrete is ready for finishing, a simple guideline is to check the footprint: for hand floating, the maximum allowable indentation is 1/4 inch (6 mm), while for power floating, it should be only 1/8 inch (3 mm) deep.

A practical test to verify the hardness of the concrete before finishing involves stepping on it. If your footprint sinks more than 1/4 inch for manual finishing or 1/8 inch for machine finish, it's not ready. This ensures that the concrete has set firmly enough to handle the finishing process without being damaged.

This is like checking the softness of a mattress. If you press down hard and your hand sinks in too deep, it’s soft and not ready for you to lie on. In the same way, if the concrete is too soft, it’s not ready for finishing.

When starting the finishing job, keep the blade flat for floating. As you progress, gradually increase the angle of the blade to impart more pressure on the concrete. However, the maximum allowable raised edge should not exceed 1 inch above the concrete surface.

Finishing involves careful manipulation of the blades on the power trowel. Initially, the blade should be kept flat to create a smooth surface. As the process advances, gradually angling the blade allows deeper pressure, perfecting the finish. However, one must be cautious not to lift the edges excessively, as this could lead to flaws in the surface texture.

Imagine smoothing out a layer of clay. At first, you flatten it with your hand. Over time, as you refine the shape and detail, you might use a tool to create deeper lines or textures. This gradual approach ensures you maintain the integrity of the material while enhancing the finish.

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