Common Defects in Bricks: Causes, Effects, and Prevention

Common Defects in Bricks: Causes, Effects, and Prevention

Bricks are a fundamental building material used in construction. However, various defects can occur during the manufacturing process, affecting the quality and durability of bricks. Understanding these defects, their causes, effects, and prevention methods is crucial for ensuring the structural integrity of brickwork. This post will explore common defects in bricks and provide insights into how to prevent them.

Common Defects in Bricks: Causes, Effects, and Prevention

Table of Common Defects in Bricks

Defect	Explanation/Causes
Over-burning of Bricks	If bricks are overburnt, a soft molten mass is produced, and the brick loses shape. Such bricks are not suitable for construction.
Under-burning of Bricks	If bricks are not burnt properly, pores are not closed due to less heat, resulting in higher water absorption and lower strength.
Bloating	This defect appears as a spongy, swollen mass over the surface of burnt bricks, caused by excess carbonaceous matter and sulphur.
Blackcore	When brick clay contains impurities like carbon and manganese, and they are not completely removed by oxidation, bricks develop a black core.
Efflorescence	Caused by alkalies in bricks. When bricks come in contact with moisture, white powder patches form on the surface, spoiling appearance.
Cracks or Checks	Occur due to lumps of lime or excess water.
Spots	If sulphide is present in brick clay, it causes dark spots on bricks, making them unsuitable for exposed masonry work.
Blisters	Broken blisters occur on the surface of bricks due to air imprisoned during moulding.
Laminations	Caused by entrapped air in voids of clay, producing weak laminations on brick faces.
Chuffs	Deformation of brick shape caused by rainwater falling on hot bricks.

Detailed Analysis of Defects

1. Over-burning of Bricks:
• Effect: Produces a soft molten mass, leading to loss of shape.
• Prevention: Monitor and control the kiln temperature to avoid excessive heat.
2. Under-burning of Bricks:
• Effect: Results in higher water absorption and lower strength.
• Prevention: Ensure sufficient heat exposure during the burning process to close pores and achieve desired strength.
3. Bloating:
• Effect: Spongy, swollen mass on brick surface.
• Prevention: Control the amount of carbonaceous matter and sulphur in the clay.
4. Blackcore:
• Effect: Bricks develop a black core due to impurities.
• Prevention: Ensure complete removal of impurities like carbon and manganese through proper oxidation during burning.
5. Efflorescence:
• Effect: White powder patches form on the brick surface.
• Prevention: Use clean, quality materials and proper curing techniques to minimize alkali content.
6. Cracks or Checks:
• Effect: Caused by lumps of lime or excess water.
• Prevention: Use well-processed clay and control the amount of water in the mix.
7. Spots:
• Effect: Dark surface spots due to sulphide.
• Prevention: Avoid using clay with high sulphide content.
8. Blisters:
• Effect: Broken blisters on brick surface.
• Prevention: Ensure proper moulding techniques to avoid air entrapment.
9. Laminations:
• Effect: Weak laminations on brick faces.
• Prevention: Properly compact the clay to remove air voids.
10. Chuffs:
• Effect: Deformation of brick shape.
• Prevention: Protect hot bricks from exposure to rainwater.

FAQs

1. What causes over-burning of bricks?
• Over-burning of bricks occurs when bricks are exposed to excessive heat, resulting in a soft molten mass and loss of shape. Such bricks are unsuitable for construction.
2. How can under-burning of bricks be prevented?
• Under-burning can be prevented by ensuring that bricks are exposed to sufficient heat during the burning process to close the pores and achieve the desired strength.
3. What is efflorescence in bricks, and how can it be avoided?
• Efflorescence is caused by alkalies present in bricks that form white powder patches on the surface when in contact with moisture. It can be avoided by using clean, quality materials and proper curing techniques.
4. Why do bricks develop blackcore, and what are its implications?
• Blackcore develops when impurities like carbon and manganese are not completely removed during burning. It indicates improper burning and can affect the brick's strength and appearance.
5. What are the effects of sulphide spots on bricks?
• Sulphide spots cause dark surface spots on bricks, making them unsuitable for exposed masonry work and potentially harmful due to the presence of sulphides.

Conclusion

Understanding the common defects in bricks, their causes, and prevention methods is essential for producing high-quality bricks and ensuring the longevity of brick structures. By addressing these issues during the manufacturing process, builders can avoid potential structural problems and maintain the integrity of their constructions.