How bricks are made

Many  ordinary Kenyan prefer brick built houses because of their relatively  low prices and  durability.  However the processing   of  manufacturing bricks -whether manual or automated -is  an expensive affair  in the sense that it is time consuming  and is likely to test the patient of anyone.

In Kenya, the process is largely a manual. However there are a few   clay works companies   with highly automated and controlled bricks manufacturing   operations.Between this two extremes  are entities that making interlocking bricks using  semi-automated  machines sold under Makiga brand name.

Bricks  are  made  by  molding  wet  or moist clay into  desired  shapes and  then left in  an open sheltered  space  to  dry for a few  days. The green bricks normally reduce in size during this drying process. Once dry, the bricks are subjected to a firing process. The  firing  temperature  is  set  high (between 940° C  to  1200° C)to   vitrify  the clay or change it  into glass like material that  is  durable  and maintenance  free.

Generally speaking bricks can be grey, yellow, blue, red, and black in color. This  color  depends  on type  of clay  used, firing  conditions and  whether  the clay went through artificial  pigment  addition  process. For example   higher temperatures and low oxygen in the Kiln will produce blue bricks. On the slip side High temperature and high oxygen   will produce red bricks. The explanation is simple-there is enough oxygen in the kiln to work on iron oxide in clay which changes it to a red color.

The standard bricks sizes are (a) 6 inches by 6 inches by 12 inches, (b) 5 inches by 6 inches by 12 inches   and (c) 4 inches by 6 inches by 12 inches. These  brick  sizes   weighs   between 2 and 4 kg, can easily held by hand and sell at between Kshs 6/ and Kshs 12/.

There are five type of bricks, namely

  1. Common bricks-These are used for  general  building work
  2. Facing bricks-These are given a finishing that make them look extra appealing than common bricks. The surface of these bricks maybe given a designed rough texture, sand faced or smoothened.
  3. Engineering bricks-they are dense with high load bearing capacity and low water absorption. They are more  expensive  because  they  require  very high  firing temperatures.
  4. Standard special bricks-This  bricks  are  designed  into  special  shapes  to  improve the quality  of building works. Examples are bullnose and radial bricks.
  5. Concrete bricks-Manufactured from a mixture of cement, sand and iron oxide pigments under high pressure in steel moulds. They harden and increase in strength with age.

Necessary precautions

When using brick on a construction project the following points should be borne in mind

  • Bricks absorb irreversibly moisture from the air after firing and as result may balloon in size slightly. It’s advisable then, that you should not use bricks within two weeks after firing.
  • Common bricks absorb water. You are well advised again not to use them in damp, soggy grounds or for damp courses. Instead use building stone or concrete blocks for the foundation and then revert to your bricks for constructing the wall above the ground.
  • Mortar used as a sealant between bricks in courses should be weaker than the individual bricks. This is to prevent cracking of bricks in the event of slight movement of the building.

Common uses of bricks and price

Bricks are excellent materials for constructing foundation and walling of buildings. Also they are used as cladding material to give building an appealing brickwork finish. Lastly they    are also used   to create brick pavements and sidewalks around buildings.

In Kenya, the prices you are likely to pay for bricks will depend on demand and supply conditions, brick size and the location   of the supplier. This price will range between Ksh.6/ and Ksh.12/per piece. Comparing this price with that of building stones or Concrete blocks, its obvious bricks relatively cheaper.


Sources:Materials  for Architects  and  Builders by Arthur Lyons PhD.


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