bricks

 Block of tampered clay or ceramic material moulded to desired shape and size, sun-dried and if required burnt to make it more strong, hard and durable is called a brick.

  Commonly it is rectangular in shape

1. Length = twice width of brick + thickness of mortar.
2. Height = multiple of the width of brick.
3. Usual size available in Pakistan is 8¾ x 4¼ x 2 ¾ inches to make it 9 x 4.5 x 3 inches with mortar.

Indian Standard size 19 x 9 x 4 cm to make it 20 x 10 x 5 cm with mortar.                                                                                                                

  Classification of Bricks

  The classification of bricks is as follows:

(i) unburnt or sun-dried bricks; and 

(ii) burnt bricks.

The unburnt or sun-dried bricks are those bricks which are dried with the help of the heat that is received from the sun after the process of moulding. The unburnt bricks can only be used in the construction of simple temporary and cheap structures. Unburnt bricks should not be used at places exposed to heavy rains.

The bricks used in construction works are burnt bricks and they are classified into the following four categories:

(1) First-class bricks

(2) Second class bricks

(3) Third class bricks

(4) Fourth class bricks.

(1) First-class bricks:

These first-class bricks are table moulded and of uniform shape and they are burnt in kilns. The surfaces and edges of the bricks are sharp, square, smooth and straight. They comply with all the qualities of good bricks. These bricks are used for important work of permanent nature.

(2) Second class bricks:

The second class bricks are ground moulded and they are burnt in kilns. The surface of the second class bricks is slightly rough and shape is also slightly regular. These bricks may have hair cracks and their edges may not be sharp and uniform. These bricks are commonly used at places where brickwork is to be provided with a coat of plaster.

(3) Third class bricks:

These bricks are ground-moulded and they are burnt in clamps. These bricks are not very hard and they have rough surfaces with irregular and blunt edges. These bricks give dull sound when they are stuck together. They are used for unimportant works, temporary structures and at places where rainfall is not heavy.

(4) Fourth class bricks:

These are overburnt bricks with irregular shape and dark colour. These bricks are used as aggregate for concrete in foundations, brick floors, surkhi, roads, etc. because of the fact that the overburnt bricks have a compact structure and hence they are sometimes found to be stronger than even the first-class bricks. It is thus seen that the above classification of bricks is based on the of manufacturing or preparing bricks.

     Types of Bricks Based on Purpose of Their Using

      Purpose of their using bricks can be following types -

1. Common bricks
2. Engineering bricks.

Common bricks: This type of bricks are used for general purpose with no special requirements. Walls that are made with this type of bricks should be plastered.

Engineering bricks: This type of bricks are burned at an extremely high temperature to form a strong and dense product. It has excellent load-bearing capacity and high damp-proof capability. 

                           

    Preparation of Brick Earth

1. Un-soiling – Removal of top 20 cm organic matter and free from gravel, coarse sand, lime etc.
2. Digging – additives spread, soil excavated, puddled, watered and leftover for weathering.
3. Weathering – heaps left for one month for oxidation and washing away of excessive salts in rain.
4. Blending – sandy earth and calcareous earth mixed in right proportions with the right amount of water.
5. Tempering – kneading of blended soil with feet or with a pug mill to improve plasticity and homogeneity.

     Characteristics of Good Bricks

1. Size and shape – uniform size, rectangular surfaces, parallel sides, sharp straight edges.
2. Colour – uniform deep red or cherry.
3. Texture and compactness – uniform texture, the fractured surface should not show fissures, holes, grits or lumps of lime.
4. Hardness and soundness – not scratchable by a fingernail. Produce metallic ringing sound.
5. Water absorption – should not exceed 20% wt.
6. Crushing strength – not less than 10.5 N/mm2.
7. Brick earth – free from stones, organic matter.                                                                                                                                                                 

Civil Engineering Uses

1. Construction of exterior and interior walls, partitions and boundary walls
2. Construction of piers,
3. Construction of footings
4. Construction of miscellaneous load-bearing structures