Using pans to float concrete offers several benefits—primarily, achieving higher F-numbers and increasing productivity. While blades follow the highs and lows of the surface, pans help remove humps and fill voids, ensuring a smoother and more level finish.
Purpose of Power Floating in Concrete Construction
According to ACI 302, the purpose of power floating is to:
- Embed large aggregate just beneath the surface
- Remove imperfections, humps, and voids
- Compact concrete and consolidate mortar at the surface in preparation for additional finishing operations
- Break open the surface, allowing the concrete to breathe and enhancing a bottom-up set
Key Benefits of Pan Floating
Using float pans for concrete flatwork provides several advantages:
- Higher F-numbers for improved flatness and levelness
- Increased productivity by covering more area efficiently
- Reduced imperfections by minimizing voids and surface inconsistencies
- Enhanced concrete strength through proper compaction and mortar consolidation
Unlike blades, floating pans distribute pressure evenly, which is essential in rebar fabrication and large-scale concrete projects.
Timing: When to Start Pan Floating
Correct timing is crucial when using power trowels and floating pans. Floating should never be done when bleed water is present, as this can lead to surface scaling and dusting.
When a finisher walking on the surface leaves only a 1/4-inch indentation, the concrete is ready for floating.
First Float Pass Best Practices
- Use low speed to prevent damaging the surface
- Apply a forward-backward technique to minimize turn marks
- Avoid high-speed, uncontrolled floating, often called cowboy floating, as this reduces flatness
- Always make the first pass perpendicular to the direction of screeding
Direction and Number of Passes
Work the edges in a backward pass because forward passes can cause the concrete to rise, creating additional edge work.
The number of passes is also important. A minimum of two passes is required, but four passes are preferred. Always keep the number of passes in multiples of two, with each pass perpendicular to the previous one.
Since walking on soft concrete can affect the surface quality, pan floating is most commonly done with riding trowels. However, smaller walk-behind or edging machines up to 36 inches are beneficial for floating edges and slab penetrations.
The Importance of Quality Float Pans
The quality of float pans plays a critical role in achieving a durable and high-performance finish. High-quality steel without soft spots extends pan life and ensures consistency.
Pans vary in thickness, with mild dish pans (1/8-inch to 1/4-inch rise from center) being the preferred choice for super flat floors. Edging pans with a 90-degree lip allow close contact with walls and penetrations, reducing the amount of necessary handwork.