Floating concrete is a technique used to achieve a smooth surface on freshly poured concrete. The process involves the use of a tool called a bull float, which is essentially a long-handled tool with a flat, rectangular blade. The bull float is used to level and smooth the concrete surface, removing any imperfections and creating a flat finish. However, when it comes to floating concrete on a setting surface, there are a few important considerations to keep in mind.
Understanding the Setting Surface
Before discussing whether or not it is possible to float concrete on a setting surface, it is crucial to understand what a setting surface is. A setting surface refers to the state of concrete when it has begun to harden and is no longer in its liquid form. During this stage, the concrete gains strength and gradually becomes solid. It is at this point that floating concrete becomes more challenging.
The Ideal Time to Float Concrete
Floating concrete should ideally be done when the concrete is at a specific stage of the setting process. It is generally recommended to wait until bleed water has evaporated from the surface of the concrete before attempting to float it. Bleed water refers to the water that is pushed to the surface during the concrete’s initial setting and drying process. Floating the concrete too early can lead to premature drying and surface damage, while waiting too long can make the concrete too hard and difficult to float.
Factors to Consider
There are several factors to consider when deciding whether or not to float concrete on a setting surface:
- Moisture content: It’s crucial to ensure that the concrete has reached the appropriate moisture content for floating. If the concrete is too wet, floating can lead to surface defects and honeycombing. On the other hand, if the concrete is too dry, floating can create excessive dust and reduce the effectiveness of the process.
- Ambient temperature: The ambient temperature plays a significant role in the setting time of concrete. Extreme hot or cold temperatures can affect the setting process, making it more challenging to achieve optimal results when floating the concrete.
- Concrete mix design: The mix design of the concrete, including the ratios of water, cement, aggregate, and additives, can influence the setting time and workability. It’s important to choose the right mix design to ensure a suitable setting surface for floating.
- Experience and skill level: The skill and experience of the person performing the concrete floating are also crucial factors. Proper technique and timing are essential to achieve the desired finish without causing any damage to the concrete surface.
Alternatives to Floating on a Setting Surface
In situations where the concrete has reached a stage where floating is difficult or not recommended, alternative methods can be used to achieve a smooth finish. These methods may include hand troweling, which involves manually smoothing the surface with a handheld trowel, or using a power trowel, which is a machine with rotating blades that levels and polishes the concrete surface.
While it is possible to float concrete on a setting surface, it requires careful consideration of various factors, such as moisture content, ambient temperature, mix design, and skill level. Floating concrete at the right time and with the right technique can result in a smooth and visually appealing finish. However, in situations where floating is not recommended, alternative methods like hand troweling or using a power trowel can be employed to achieve a similar result.