Reinforced Concrete Slab Thickness

The given problem states that a reinforced concrete slab is 75 mm thick, and we need to determine the maximum size of reinforcement bar that can be used. Let's analyze the factors that influence this decision.

Factors Affecting Reinforcement Bar Size

1. Concrete Cover: The concrete cover is the distance between the surface of the reinforcement bar and the outer surface of the concrete. It provides protection to the reinforcement against corrosion and fire.
2. Minimum Clear Distance: There should be a minimum clear distance between adjacent reinforcement bars to ensure proper concrete flow during construction and to allow for proper compaction.
3. Maximum Aggregate Size: The maximum size of the coarse aggregate used in the concrete mix affects the spacing between reinforcement bars.
4. Structural Requirements: The design and structural requirements of the slab play a crucial role in determining the maximum size of the reinforcement bar.

Concrete Cover and Minimum Clear Distance

According to standard practices and design codes, the minimum concrete cover for reinforcement bars in slabs is typically 20 mm. This cover provides adequate protection to the reinforcement against corrosion and fire. Additionally, a minimum clear distance of 10 mm is required between adjacent reinforcement bars.

Maximum Aggregate Size

For a 75 mm thick concrete slab, it is common to use a maximum aggregate size of 20 mm. This means that the largest particle size in the concrete mix is 20 mm, and it affects the spacing between reinforcement bars.

Structural Requirements

The structural requirements of the slab, such as the span, loads, and design considerations, also influence the maximum size of the reinforcement bar. Without specific information about the structural requirements, it is difficult to determine the exact maximum size. However, based on general practices, it is safe to assume that a maximum size of 8 mm reinforcement bars can be used for a 75 mm thick concrete slab.

Conclusion

Based on the given information and general practices in the construction industry, the maximum size of reinforcement bar that can be used for a 75 mm thick concrete slab is 8 mm in diameter.

75/8=9.375 . hence 8mm dia bar can be used