Bricks...my son wants to know how they are made?

Question

- and what are they made from?
They are not cut from the ground, he says, so can anyone tell us how they are made?

Answer 1

Bricks may be made from clay, shale, soft slate, calcium silicate, concrete, or shaped from quarried stone.

Clay is the most common material, with modern clay bricks formed in one of three processes - soft mud, dry press, or wire cut.


[edit] Mud bricks
The soft mud method is the most common, as it is the most economical. It starts with the raw clay preferably in a mix with 25-30% sand to reduce shrinkage. The clay is first ground and mixed with water to the desired consistency for forming in a mould. The clay is pressed into steel moulds with a hydraulic press. The shaped clay is then fired ("burned") at 900-1000°C to achieve strength.


[edit] Rail kilns
In modern brickworks, this is usually done in a continuously fired tunnel kiln, in which the bricks move slowly through the kiln on conveyors, rails, or kiln cars to achieve consistent physical characteristics for all bricks. The bricks often have added lime, ash and organic matter to speed the burning.


[edit] Bull's Trench Kilns
In Pakistan and India, brick making is still typically a manual process. The most common type of brick kiln in use there are Bull's Trench Kiln (BTK), based on a design developed by British engineer W. Bull in the late 1800s.

An oval or circular trench, 6-9 meters wide, 2-2.5 meters deep, and 100-150 meters in circumference, is dug in a suitable location. A tall exhaust chimney is constructed in the center. Half or more of the trench is filled with "green" (unfired) bricks which are stacked in an open lattice pattern to allow airflow. The lattice is capped with a roofing layer of finished brick.

In operation, new green bricks, along with roofing bricks, are stacked at one end of the brick pile while cooled finished bricks are removed from the other end for transport. In the middle the brickworkers create a firing zone by dropping fuel (coal, wood, oil, debris, etc) through access holes in the roof above the trench.

The advantage of the BTK design is a much greater energy efficiency compared with clamp or scove kilns. Sheet metal or boards are used to route the airflow through the brick lattice in such a way that fresh air flows first through the recently burned bricks, thus heating the air, then through the active burning zone. The air continues through the green brick zone (pre-heating and drying them), and finally out to the chimney exhaust where the rising gases create the suction which pulls the air through the whole system. The reuse of heated air results in a considerable savings in fuel cost.

As with the rail process above, the BTK process is a continuous one. A half dozen laborers working around the clock can fire approximately 15,000-25,000 bricks a day. However, unlike the rail process, in the BTK process the bricks themselves do not move. Instead the locations at which the bricks are loaded, fired, and unloaded gradually rotate through the trench. [1]


[edit] Dry pressed bricks
The dry press method is similar to mud brick but starts with a much thicker clay mix, so forming more accurate, sharper-edged bricks. The greater force in pressing and the longer burn make this method more expensive.


[edit] Wire cut bricks
In wire cut the clay mix is 20-25% water, this is forced through a die to create a long cable of material of the demanded width and depth. This cable is then cut into bricks of the desired length by a wall of wires. The majority of structural bricks are made by this method as hard dense bricks are the result and any needed holes or other perforations can be introduced by the die. The introduction of holes reduces the needed volume of clay through the whole process, with the consequent reduction in costs per brick. The bricks are also lighter and so easier to handle and have different thermal properties compared to solid bricks. The cut bricks are hardened by drying for between 20 and 40 hours at 50-150°C before being burned. The heat for the drying is often the waste heat of the burning process.

Answer 2

They are made from clay dug out of the ground, mixed with some water and shaped to form `green` bricks. They are then dried out slowly for a while and then baked in a kiln at a temp of between 1000-1200 degrees C.

Answer 3

Bricks are made from clay which they help for when building things like houses.

Answer 4

Red/brown bricks are made from clay, water and fine sand/slit...baked in an oven. Cinder blocks are made from concrete.

Answer 5

tyeyare made of clay...i worked in the brickworks for many years ..and have made millions of them ..the clay is drawn out of the ground and is treated with machinery and steam etc to make it malable ...and is then pressed into moulds ..then into a dryer ..then the kiln to be burnt ..when i first whent into the brickyards ..we were paid 20 pence per thousand to draw them out !

Answer 6

bricks r made from clay putinto a verry hot fernes

Answer 7

Basically they are clay of various kinds, moulded into shape and baked to a very high temperature.

Answer 8

They are made from clay, water and sand and then baked. Did you know that if you dip them in a bucket of water, you can bend them to shape?!

Answer 9

clay with some extras then baked in a huge oven.

Answer 10

bricks are akin to most ceramics, you start with a concrete type mixture, this is puored into a special mold, then baked.