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A short class with Sarah and her students. The other ways are under More.
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Today, we’re exploring important tools in the finishing of concrete: power floats and trowels. Does anyone know what these tools look like?
Are they the machines that look like spiders?
Exactly! They are often called 'spiders' due to their shape. Let’s discuss how they work. They have rotating blades inside that help finish the concrete surface. Can anyone tell me how the operation differs between floating and troweling?
I think floating keeps the blades flat, but troweling angles them more.
Right! Floating requires a flat blade for a smooth finish, while troweling applies more pressure by angling the blade. Remember the acronym PACE: Pressure, Angle, Consistency, and Efficiency, to help encapsulate these differences in operation.
How productive are these machines compared to manual finishing?
Great question! Manual finishing can yield 30 to 60 square meters per day, while with power floats and trowels, we can achieve up to 140 square meters. This showcases their efficiency. Remember: 'Machines boost productivity!'
Now that we understand the machines, how do we know when the concrete is ready for finishing?
Is it about the bleed water on the surface?
Correct! The concrete must be free of bleed water and adequately cured before using machines. ACI guidelines state that a worker's footprint shouldn’t exceed 3 mm before machine finishing, as opposed to 6 mm for manual floating. Can anyone summarize why checking the footprint is important?
It helps ensure the concrete isn't too soft to hold up the machine.
Exactly! The concrete must withstand the machine's weight. Let's remember: 'Test the pressure, then apply the pressure.'
When we start floating, what's a key point to remember about the angles of the blades?
We need to keep the blades flat at first, right?
Yes! Start with flat blades to smoothen the surface. As you progress, gradually increase the angle. Who can tell me the maximum height for raised edges?
One inch above the surface!
That's right! Maintaining a maximum edge thickness is crucial. Always remember: 'Flatter first, then angle clear!'
What happens if we exceed that height?
Exceeding one inch can lead to inconsistency in the finish, which is not desirable. Always aim for a consistent texture!
Let’s recap! What's one key takeaway about the productivity of using power floats?
They can finish up to 140 square meters per day compared to manual, which is much lower.
Exactly! And remember, what should we check before starting any finishing work?
We must ensure the concrete is cured and free of bleed water.
Correct! And what’s one technique we discussed for floating?
Start with flat blades and only increase the angle as needed!
Well done everyone! Keep 'PACE' in mind as we move on to the next topic.
Machines that can finish concrete rapidly compared to manual methods.
Importance of checking bleed water and curing before using finishing tools.
Changing blade angles for floating and troweling to optimize surface finish.
Power tools significantly increase the area covered in finishing tasks.
For concrete that's ready, check the water, make sure it's steady!
Imagine a builder with a paint sprayer; if the paint is too thick, it won't cover smooth. Just like with concrete finishing, if the surface is not prepared, tools won't work as they should.
PACE: Pressure, Angle, Consistency, Efficiency - helps remember the key aspects of operation and best practices.
FRESH: Free of bleed water, Ready for machine use, Ensure flat blades, Smooth finish, Height not exceeding one inch!
Term
What are power floats used for?
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Term
What should concrete be free of before finishing?
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A machine equipped with rotating blades used to finish concrete surfaces smoothly.
A tool used to smooth and shape concrete while adding a level of finish.
Water that rises to the surface of newly poured concrete as it sets, which must be removed before finishing.
The indentation left by a worker's foot on wet concrete, indicating the hardness and readiness for finishing.
The ability to change the angle of the blades on finishing machines to suit different tasks.
This section discusses the use of power floats and trowels in the finishing of concrete, focusing on productivity, machine operation, and guidelines for optimal results.
The section details the functionality of power floats and trowels in concrete finishing, emphasizing the advantages of machine-based methods over manual techniques. It highlights productivity rates, machine operation specifics, and guidelines for preparing concrete prior to finishing to ensure optimal surface quality.
This section elaborates on the use of power floats and power trowels, machines designed for effective finishing of concrete surfaces. Power floats, sometimes nicknamed 'spiders' due to their appearance, utilize rotating blades to create smooth finishes. The section differentiates between floating and troweling operations: while floating uses flat blades, troweling requires angled blades and increased pressure, enhancing surface consistency.
Furthermore, it highlights productivity differences, indicating that power floats can achieve up to 140 square meters of finishing per day compared to the 30 to 60 square meters possible manually. The choice of machine configuration—walk-behind or ride-on—should align with project needs.
Crucial guidelines for the finishing process are provided, primarily concerned with concrete readiness. Before using machines, it’s essential that concrete has cured sufficiently and is free of bleed water. Guidelines from the ACI manual recommend assessing surface hardness by testing the footprint's depth left by a worker’s foot; a maximum of 1/4 inch indicates readiness for manual finishing, while only 3 mm is permissible for machine-based floating.
Lastly, the procedure for floating involves gradually adjusting the blade's angle to apply increased pressure, ensuring no raised edges exceed one inch above the surface. The section collectively emphasizes the importance of proper equipment operation and readiness checks for achieving high-quality concrete finishes.