When you start planning a construction project, one of the first things you’ll hear is about the type of bricks to be used. Among them, Class A and Class B bricks are the most common categories in India and many other countries. But what are Class A and Class B bricks, and how do they differ? Understanding these brick classifications is essential for choosing the right materials for your project, ensuring strength, durability, and cost-effectiveness. In this article, we’ll explore everything you need to know about Class A and Class B bricks, their properties, uses, advantages, disadvantages, and how to select the right one for your building.
Classification of Bricks in Construction
Bricks are generally classified based on strength, size, surface finish, and durability. In India, the Bureau of Indian Standards (BIS) specifies guidelines in IS 1077:1992 – Common Burnt Clay Building Bricks. According to these standards, bricks are divided into different classes such as Class A, Class B, Class C, and so on. Among these, Class A and Class B bricks are the most widely used in regular construction.
What Are Class A Bricks?
Class A bricks are the highest quality bricks used in construction. They are uniform in shape, size, and color. They have high compressive strength and very low water absorption. Because of their quality, Class A bricks are often used in projects where strength and appearance both matter.
Properties of Class A Bricks
- Compressive strength: Not less than 10.5 N/mm²
- Water absorption: Less than 15% by weight after 24 hours of immersion
- Uniform shape and smooth surface
- High durability and resistance to weathering
- Minimal efflorescence (white patches caused by salt deposits)
Uses of Class A Bricks
- Load-bearing walls
- Foundations
- Exposed brickwork for aesthetic finishes
- Multi-story buildings where strength is crucial
What Are Class B Bricks?
Class B bricks are slightly lower in quality compared to Class A bricks but are still widely used in construction. They are not as uniform in shape and size, and their surface may have slight roughness. However, they provide good strength and are more economical than Class A bricks.
Properties of Class B Bricks
- Compressive strength: Not less than 7 N/mm²
- Water absorption: Less than 20% by weight after 24 hours of immersion
- Slightly irregular shape and rough texture
- Moderate durability
- May show some efflorescence on drying
Uses of Class B Bricks
- Internal walls and partitions
- Boundary walls
- General-purpose masonry work
- Non-load-bearing walls
Difference Between Class A and Class B Bricks
Here’s a detailed comparison between Class A and Class B bricks:
| Feature | Class A Bricks | Class B Bricks |
|---|---|---|
| Strength | ≥ 10.5 N/mm² | ≥ 7 N/mm² |
| Water Absorption | < 15% | < 20% |
| Shape & Size | Uniform, smooth | Slightly irregular |
| Surface Finish | Smooth and even | Rough or uneven |
| Appearance | Better, often used for exposed work | Less attractive, needs plastering |
| Cost | Higher | Lower |
| Durability | Very high | Moderate |
| Best Uses | Foundations, load-bearing walls, aesthetic finishes | Internal walls, partition walls, general masonry |
Advantages of Class A Bricks
- High strength ensures structural stability
- Low water absorption prevents dampness
- Smooth finish suitable for exposed walls without plaster
- Long-lasting durability
- Resistant to weathering and efflorescence
Disadvantages of Class A Bricks
- Higher cost compared to other bricks
- Heavier in weight, leading to more labor costs
- Not always locally available in all regions
Advantages of Class B Bricks
- Economical option for construction
- Readily available in most markets
- Adequate strength for general masonry work
- Suitable for plastered surfaces where finish does not matter
Disadvantages of Class B Bricks
- Irregular shape and rough surface
- Higher water absorption compared to Class A bricks
- Moderate durability, not suitable for heavy load-bearing structures
- Requires plastering for better finish
Factors to Consider When Choosing Between Class A and Class B Bricks
When deciding between Class A and Class B bricks, consider the following factors:
- Purpose of construction: For load-bearing walls, Class A is better, while for partition walls, Class B works fine.
- Budget: Class A bricks are costlier, so if you’re working with a tight budget, Class B bricks may be more practical.
- Location: In coastal or high-rainfall areas, Class A bricks are preferred due to their low water absorption.
- Aesthetic needs: If you want exposed brickwork, Class A bricks provide a cleaner and more uniform look.
Tests to Identify Class A and Class B Bricks
At a construction site, you can perform some simple tests to distinguish between Class A and Class B bricks:
- Drop Test: A good Class A brick will not break when dropped from about 1 meter height.
- Scratch Test: Scratching with nails should not leave powdery marks on Class A bricks.
- Sound Test: When two Class A bricks are struck together, they produce a metallic ringing sound. Class B bricks give a dull sound.
- Water Absorption Test: Immerse a brick in water for 24 hours and measure the weight difference. Class A absorbs less than 15%, Class B less than 20%.
Common Applications of Class A and Class B Bricks in India
- Class A Bricks: Used in foundations, pillars, arches, facades, government buildings, schools, and high-rise apartments.
- Class B Bricks: Used in rural housing, compound walls, temporary structures, low-cost housing, and partition walls.
FAQs on Class A and Class B Bricks
What is the main difference between Class A and Class B bricks?
The main difference lies in strength, water absorption, and finish. Class A bricks are stronger, more durable, and smoother, while Class B bricks are slightly weaker and rough in finish.
Are Class B bricks suitable for load-bearing walls?
Class B bricks are generally not recommended for heavy load-bearing walls. Class A bricks are more reliable for such applications.
Which type of brick is more cost-effective?
Class B bricks are more cost-effective for general masonry work, while Class A bricks are worth the higher price for critical structures.
Can Class B bricks be used in foundation work?
It is better to use Class A bricks for foundations due to their higher strength and durability. Class B bricks may not perform well in long-term heavy loads.
Which brick class is better for exposed brickwork?
Class A bricks are better for exposed brickwork because of their uniform shape, smooth finish, and better appearance.
Final Thoughts
So, what are Class A and Class B bricks? In short, Class A bricks are premium-quality bricks with high strength, low water absorption, and excellent durability, suitable for structural and aesthetic applications. Class B bricks, while slightly inferior in quality, are cost-effective and suitable for non-load-bearing and general-purpose construction. Both types of bricks have their place in the construction industry, and the choice depends on your project needs, budget, and environmental conditions.
