DEFECTS OF BRICKS
1. Over-Burning of Bricks
- If the bricks are overburnt, a soft molten mass is produced and the bricks lose their shape. Such) bricks are not used for construction works.
2. Under-Burning of Bricks
- When bricks are not burnt properly, the clay is not softened because of insufficient heat and the pores) are not closed.
- This results in a higher degree of water absorption and less compressive strength Such bricks are not recommended for construction works.
- This defect is observed as a spongy swollen mass over the surface of burned bricks. It is caused due to the presence of excess carbonaceous matter and sulphur in brick-clay.
- When brick-clay contains bituminous matter or carbon and they are not completely removed by oxidation, the brick results in black core mainly because of improper burning.
- This is caused because of alkalies present in bricks. in contact with moisture, water is absorbed and the alkalies crystalise.
- When bricks come After drying grey or white powder patches appear on the brick surface. This can be reduced by selecting proper clay materials for brick manufacturing, preventing moisture to come in contact with the masonry, providing waterproof coping and by using water repellent materials in the mortar and providing a damp proof course.
- Deformation of the shape of bricks caused by the rainwater falling on hot bricks is known as chuffs.
- This is because of lumps of lime or excess water.
- In the case of lime, when bricks come in contact with water, the absorbed water reacts with lime nodules causing expansion and consequent disintegration of bricks, whereas shrinkage and burning cracks result when the excess water is added during brick manufacturing.
- If sulphide, is present in the brick clay, it causes dark surface spots on the brick surfaces. Such bricks are not only harmful but also unsuitable for exposed masonry work.
- Broken blisters are generally caused on the surface of sewer pipes and drain tiles due to air imprisoned during their moulding.
- It is by the entrapped air in the voids of clay. Laminations produce thin lamina on the brick faces which weather out on exposure.
- Such bricks are weak in structure.