Defects in bricks

Different Types of defects in Bricks which must taken care of before using the bricks at construction site.

1. Defects In Bricks

2. Over burning of bricks

3. Over burning of bricks When bricks over-burn, soft molten mass is produced and the brick will its shape along with other designated requirements. Bricks  should be  burned  at temperatures at which incipient, complete and viscous vitrification occur. However, if the  bricks  are  over  burnt, a soft molten mass is produced and the  bricks  loose their shape. Such  bricks  are not used for construction works. We know that,clay is used for the production of bricks.For the production of brick,we have to change the nature of clay from loosen state to harden state by heating. During the production of bricks, we have to burnt bricks to achieve sufficient hardness after moulding clay into a required shape.During heating,if the brick overburnt,then soft molten mass is produced and the brick looses its required shape.

4. Under burning of bricks

5. Under burning of bricks When bricks are not burnt to cause complete vitrification, the clay is not softened because of insufficient heat and the pores are not closed. This causes non softening of clay, it could not complete the vitrification process. The result of under burning of clay is a less compressive strength. Consequently, bricks with low compressive strength and high-water absorption will be produced. They produce a dull sound when struck against each other. Finally, such bricks are not recommended for construction works

6. Black Core in the bricks As the name suggests a black core is a circular or semi-circular shaped black or grey spots formed around the core or middle portion in fire clay bricks. These are not desirable since presence of black core spots reduces the normal life of a refractory brick and sometimes , also cause blotting in the furnace.

7. Black Core in the bricks Reason behind formation of Black core Presence of carbonaceous matters in plastic / non plastic fire clays which have been used as a raw material in manufacturing those refractory Bricks. Sometime , excess carbonaceous matter and sulphur have been found to occur in the fire clays available particularly nearby a coal-belt. Because of too much reducing atmosphere in the kiln during firing of these refractory bricks. Read More: https://www.industry.guru/black-core-defects-in-fire-clay-refractory-bricks-causes-and-remedies-155.html

8. Bloating of bricks Bloating of bricks is spongy swollen mass over the surface of burned bricks. Presence of excess carbonaceous matter and Sulphur in brick-clay is the main cause of bloating.

9. Efflorescence Presence of drying grey or white powder patches on the brick surface is the efflorescence indicator. This defect is caused because of alkalis present in bricks. When bricks come in contact with moisture, water is absorbed and the alkalis crystalize. Efflorescence  is a crystaline , salty deposit that occurs on the surfaces of  bricks , concrete and other masonry products. ... In order for  efflorescence  to occur, there must be water present to dissolve and transport the salts to the  brick  surface. Water from the grounds surface can often be the cause of  efflorescence . Lastly, efflorescence can be minimized by selecting proper clay materials for brick manufacturing, preventing moisture to come in contact with the masonry, by providing waterproof coping and by using water repellent materials in mortar and by providing damp proof course.

10. Efflorescence This can be minimized by implementing any of the following methods, such as- Selecting proper clay materials for brick manufacturing Preventing moisture to come in contact with the masonry, By providing waterproof coping and By using water repellent materials in mortar and by providing damp proof course.

11. Brick Cracking Straight Cracks – Straight cracks at right angles from one of the long surfaces of the brick will develop. Considerably rapid drying is the cause of straight cracks. Possibly, brick damage occurs even if fired adequately. B. Random Cracks – Cracks initiate arbitrarily on different brick surfaces. Differential drying generate shrinkage. then, various lumps of dried materials will shrinkage differently which eventually lead to random cracking. additionally, the presence of pebbles in clay mix could lead to random cracking as well.

12. Brick Spalling In construction ' spalling ' refers to the flaking, cracking, peeling, crumbling or chipping of stone or  bricks , particularly where areas of the surface are said to have blown. This can occur as a result of water penetration, freezing, heating (such as during a fire) or by mechanical processes. Causes: Irregular portion of the brick break away of fall off. Heating of water inside brick is the cause of spalling Read More : https://www.heritage-house.org/stuff-about-old-buildings/brick-and-stone/brickwork-spalling.html

13. Chuffs The deformation of the shape of bricks due to rain water falling on hot bricks is known as chuffs. Lamination in Bricks Thin lamina produces on the brick faces which weather out on exposure. Entrapped air in the voids of clay is the cause of laminations. Such bricks are weak in structure. Blisters Broken blisters due to air entrapped during moulding

14. Spots It is a dark spot on brick surface. The presence of iron sulphide in clay brick is the main cause of spots. Bricks with sports on its surface is unsuitable for exposed masonry work.

15. Lime Blowing Disintegration of bricks is the indicator of lime blowing. If bricks contain lime lump, then lime blowing is expected. The lime absorb water and expand after its exposure to firing. Consequently, lime blowing will take place. Bricks susceptible to lime blowing can be identified by submerging the brick in water. As a result, the brick fractures and powdery lumps will be exposed.

16. Defects in Brick Size Brick oversize in width, length, and thickness Size defects make bricks lighter than normal bricks Oversize in all three dimensions of bricks might cause by under-firing, poor material selection and preparation. For example, presence of too much sand that decline among of drying. Oversize in width and length occur due to brick squashing while it is still wet. This may have been occurred when the brick was set down on the ground or drying rack after being molded or when a slop molded brick was pressed to flatten out a distortion. Oversize in thickness, which is common problem in wire cut bricks, occurs during brick wire cutting. the block of clay is forced through a row of wires. As a result, the force on the wire may cause movement that changes the dimension of the opening which the clay passes through.

17. Defects in Brick Size Oversize in thickness, which is common problem in wire cut bricks, occurs during brick wire cutting. the block of clay is forced through a row of wires. As a result, the force on the wire may cause movement that changes the dimension of the opening which the clay passes through. Under Size Bricks :- This problem occurs due to several factors for example, faulty mould, presence of too much clay in the batch, using too much water during the mixing stage, and over firing.

18. Defects in Brick Shape Slump Brick Shape : It occurs when clay mix is considerably wet, so it slumps under its weight. Rounded Corner Brick : Corner breakage between drying and firing may cause this problem. Another factor is that, the worker does not push clay into the mould properly. Lip on bed face : Excessive clay is not removed from the face of the brick during manufacturing is the cause of presence of lip on brick bed face. Leaving flashing around brick top edge border during production process is another factor that led to this issue. Banana Brick Shape : It occurs when the brick is not turned around during initial drying phase prior to the hardening of top face.

19. Defects in Brick Shape Contaminated or distorted of brick under face : surface on which bricks are dried is either uneven or dirty of combination thereof. Frequently it occurs with slope moulding as wetter mixture picks up more particles. Stacking marks on Brick : Brick Distort. Bricks get finger or other marks. Moving bricks from individual drying to stack drying before it is dried adequately is the cause of stacking bricks. Brick multiple distortions : Brick loses its shape and suffer different distortions at the same time. Brick forming may be cause of Multiple distortions. Brick handling my cause many distortions like handling with Clamp.

20. Other Defects in Bricks Iron Staining : Iron salts can form a significant part of natural clay materials. Iron staining occurs on some “stock” bricks and on certain types of wire-cut bricks, particularly those made with clays with a high iron content. It takes the form of a dark brown stain leeching from the brick body. If, after production, the bricks are exposed to saturation in certain conditions iron salts will migrate to the surface, in much the same way as the common white efflorescence, where they oxidise to produce a stain that is usually brown in colour , very similar to rust. White Scum (Silicate Deposits) : Silicate deposits appear as uneven  white  or grey stain on the  brick  face or mortar joints. It often appears as vertical run marks, which do not disappear when wet. The cause is inadequate pre-wetting or rinsing when cleaning with muriatic acid or other acidic solutions.