Cover block uses are very important in reinforced cement concrete construction because they help maintain the required clear cover between reinforcement bars and concrete surface. Cover blocks ensure durability, strength, and safety of RCC members by protecting steel from corrosion, fire, and environmental damage. Without proper use of cover blocks, even a well-designed structure can fail prematurely.
What Is a Cover Block
A cover block is a small block placed between reinforcement bars and shuttering to maintain the specified concrete cover. It is usually made of concrete with strength equal to or greater than the structural concrete. Cover blocks are available in different shapes and sizes depending on slab, beam, column, or footing requirements.
Main Uses of Cover Blocks in Construction
Cover blocks are used to keep reinforcement in the correct position during concreting. They prevent steel bars from touching shuttering or soil, which can lead to corrosion and strength loss.
Key Uses of Cover Blocks
- Maintain required clear cover to reinforcement
- Protect steel bars from corrosion and moisture
- Improve fire resistance of RCC members
- Ensure proper bond between steel and concrete
- Maintain effective depth of RCC sections
Cover Block Uses in Different RCC Members
Cover blocks are used differently depending on the structural element.
Cover Block Uses in Slabs
In slabs, cover blocks maintain bottom cover and ensure reinforcement stays at the correct level. This helps achieve designed slab thickness and bending strength.
Cover Block Uses in Beams
In beams, cover blocks are used at the bottom and sides to protect main reinforcement and stirrups. Proper cover improves durability and crack resistance.
Cover Block Uses in Columns
In columns, cover blocks are tied to reinforcement cages to maintain uniform cover on all sides. This is essential for fire resistance and long-term strength.
Cover Block Uses in Footings
In footings, cover blocks prevent reinforcement from resting directly on soil. This protects steel from moisture and chemical attack present in the ground.
Types of Cover Blocks Based on Material
Cover blocks are classified based on material and application.
Concrete Cover Blocks
These are the most commonly used and recommended cover blocks. They provide better bonding and durability compared to other materials.
Plastic Cover Blocks
Plastic cover blocks are lightweight and easy to fix. They are mainly used in slabs and columns but must be of good quality to avoid deformation.
Advantages of Using Cover Blocks
Using cover blocks offers several technical benefits in RCC construction.
Main Advantages
- Increases durability of RCC structures
- Reduces corrosion risk of reinforcement
- Ensures accurate reinforcement placement
- Improves structural safety
- Helps meet code requirements
Common Mistakes in Using Cover Blocks
Improper use of cover blocks can reduce structural performance. Using broken bricks, stones, or undersized blocks is a common site mistake. Uneven placement of cover blocks can cause variable cover, leading to cracks and corrosion.
Standard Cover Block Sizes
Cover block size depends on the required cover for each RCC member. Common sizes include 15 mm, 20 mm, 25 mm, 40 mm, and 50 mm. The correct size should always be selected as per design and exposure condition.
FAQs on Cover Block Uses
Why are cover blocks necessary in RCC
Cover blocks are necessary to maintain proper concrete cover, which protects reinforcement and ensures durability.
Can bricks be used instead of cover blocks
No, bricks are not recommended because they absorb water and do not provide uniform cover.
Which cover block is best for slabs
Concrete or high-quality plastic cover blocks of correct size are best for slabs.
What happens if cover blocks are not used
Without cover blocks, reinforcement may shift, reducing cover and leading to corrosion and structural damage.
Conclusion
Cover block uses are essential for achieving strong, durable, and long-lasting RCC structures. They ensure correct reinforcement placement, protect steel from corrosion, and help meet design and code requirements. Proper selection and placement of cover blocks should never be ignored, as they play a critical role in the overall performance of concrete structures.
