Finishing of Surface
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Initial Finishing
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Let's start with initial finishing. What do you think is the purpose of this step?
I think it's about making the surface smooth.
Exactly! We achieve this by using longitudinal and transverse screeds. Can anyone explain what screeds actually do?
They help level out the concrete after it's laid.
Correct! They ensure that the surface is appropriately shaped and ready for the final finishing. Remember, a well-finished surface enhances both functionality and appearance.
Final Finishing Techniques
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Now that we've covered initial finishing, let’s talk about final finishing techniques. What methods can you think of that give a concrete surface grip?
There's the burlap drag method, right?
Great recall! The burlap drag creates a rough surface for skid resistance. Anyone else?
Broom finish is another technique.
Exactly! Broom finishing enhances surface texture further. Tining is also a method used to imprint patterns for drainage. Can anyone remember why texture is important?
It helps prevent slipping, especially when wet.
Yes! Skid resistance is vital for safety. Remember, we aim for a surface tolerance of ±3 mm over 3 m. That's a key specification!
Quality Assurance
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Now, let’s focus on surface tolerance. Why do you think it's necessary to maintain a tolerance of ±3 mm?
To ensure that the concrete is level?
Correct! Maintaining a uniform surface is critical for load distribution and durability. What might happen if we don’t meet this standard?
It could lead to cracking or water pooling, right?
Exactly! Poor surface tolerance affects performance and lifespan of the pavement. Always monitor this during finishing.
Introduction & Overview
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Quick Overview
Standard
In this section, we learn about the critical processes involved in finishing cement concrete surfaces, particularly the methods used for initial and final finishing, including the importance of surface tolerances in ensuring quality and performance in pavement construction.
Detailed
Finishing of Surface
The finishing of cement concrete pavements is a crucial phase in the pavement construction process, focusing on achieving a surface that meets both aesthetic and functional requirements. The finishing process is divided into two main stages:
- Initial Finishing: This stage involves the use of longitudinal and transverse screeds to level the surface of the fresh concrete. The purpose is to ensure the surface is smooth and free of imperfections.
- Final Finishing: In this stage, the concrete surface is treated to provide skid resistance and enhance durability. Common techniques include:
- Burlap Drag: This method uses a damp burlap to create a textured surface that improves skid resistance.
- Broom Finish: A broom is drawn across the surface to create a rough texture.
- Tining: A specialized tool is used to imprint lines that further enhance surface drainage and skid resistance.
Additionally, it's important to maintain surface tolerance, which is typically ±3 mm over a 3 m straightedge. Adhering to these finishing standards is vital for the longevity and performance of concrete pavements.
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Initial Finishing
Chapter 1 of 3
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Chapter Content
Initial Finishing: Done using longitudinal and transverse screeds.
Detailed Explanation
The initial finishing of a concrete surface is the first step in preparing it for use. This process involves using tools called screeds, which are long, straight boards that smooth out the wet concrete. Longitudinal screeds run along the length of the pavement while transverse screeds are used across the width. Together, they help to create a flat and level surface, which is crucial to ensure the durability and functionality of the pavement.
Examples & Analogies
Think of initial finishing like icing a cake. Just as you use a knife to spread the icing evenly over the surface of the cake, the screeds help to ensure the concrete is smooth and even before it sets.
Final Finishing
Chapter 2 of 3
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Chapter Content
Final Finishing: Texturing using burlap drag, broom finish, or tining for skid resistance.
Detailed Explanation
After the initial finishing is complete, the final finishing process adds texture to the surface of the concrete. This is important for providing skid resistance, which helps prevent accidents caused by slippery surfaces. Methods of final finishing can include dragging a burlap sack across the surface to create a rough texture, using a broom to add grooves, or tining methods that create small, linear indentations for better grip. Each of these methods is designed to enhance safety and functionality.
Examples & Analogies
Imagine walking on a wet floor versus walking on a floor with a rough mat. The rough surface provides more grip and prevents slipping. Similarly, the texturing of concrete pavement gives vehicles better traction, especially in wet conditions.
Surface Tolerance
Chapter 3 of 3
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Chapter Content
Surface tolerance: ±3 mm over 3 m straightedge.
Detailed Explanation
Surface tolerance specifies how level the finished concrete must be. A tolerance of ±3 mm over a 3-meter (m) straightedge means that when you place a straight edge over the concrete, the highest point can be no more than 3 mm above or below the straightedge. This is important because a concrete surface that meets this standard is less likely to develop issues over time such as cracking or water pooling, which can lead to safety hazards.
Examples & Analogies
Consider how a well-paved road feels compared to a bumpy one. If the road is too uneven, it can cause cars to jostle and even damage suspensions. Maintaining the proper surface tolerance in pavement ensures a smoother and safer driving experience.
Key Concepts
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Initial Finishing: The first stage of surface treatment to level the concrete using screeds.
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Final Finishing: The second stage using techniques like burlap drag, broom finish, and tining to enhance surface properties.
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Surface Tolerance: The maximum allowable deviation in surface flatness, critical for performance and safety.
Examples & Applications
Example of burlap drag: Used in high-traffic areas to improve safety and reduce slipping.
Broom finish example: Commonly applied in sidewalks for better traction.
Memory Aids
Interactive tools to help you remember key concepts
Rhymes
Before the concrete gets its flair, we screed it smooth with utmost care. For texture fine, we use the broom, then burlap drags to break the gloom.
Stories
Once, a contractor laid a thick slab but it was too bumpy. With a screed, they smoothed it out, ensuring the surface was comfy. They used a broom to give it a grip and burlap to provide a good slip.
Memory Tools
BBS: Broom, Burlap, Screed - remember these techniques for better concrete finish!
Acronyms
FLEX
Finishing Level for Excellent eXecution in concrete works.
Flash Cards
Glossary
- Screed
A tool used to level freshly laid concrete.
- Burlap Drag
A finishing technique using wet burlap to texture the concrete surface for better skid resistance.
- Broom Finish
A method to create a textured surface using a broom.
- Tining
A finishing technique that involves creating grooves or lines on the concrete surface.
- Surface Tolerance
The allowable deviation in surface flatness, typically set at ±3 mm over 3 meters.
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