How bricks are made – materials,manufacturing of bricks,moulding of bricks,burning of brick

 How bricks are made – materials,manufacturing of bricks,moulding of bricks,burning of brick

Brick

Bricks are made from clay.  In order to make a good quality  brick  following components are required in proper  proportion.

Components of clay for making brick

1) Alumina:  Alumina makes  easy to construct clay. Proportion of alumina is about 20 to 30%. High content of alumina causes bending of brick during burning of bricks. High content of alumina also causes contraction of brick.

 

2)Silica: 50 to 60% of silica alone or with alumina make bricks hard, strong, and reduce shrinkage of the bricks. It does not causes wrinkle during burning of brick.  If the silica is excessive, the bricks become brittle and porous and cause problems during combustion.

 

3)Lime:- If about 5% lime is their in brick then it will reduce contraction and also provide binding material in brick. Its increase compressive strength of brick.

4)Iron Oxide: approximately about 5% Iron oxide is provided. Iron oxide provide reddish colour to brick. Their is no vital role of iron oxide in strength. Higher iron oxide makes brick soft.

5)Magnesia : If there is a small amount of magnesia, the bricks become yellow and the contractions of the bricks decreases.

Steps of manufacturing of Bricks 

Frist clay is prepared for making of brick

 

1)Cleaning and digging:

Remove the leaves, grass, stones, roots, vegetation, pebbles, etc. from the topmost layer of the soil, then dig and get soil lumps and crush it.

2)Weathering :

Sprinkle water on broken lumps of excavated soil and allow it to air for a few months, during this time soils are shake two-three times.

3)Blending:

 Add the ingredients as needed and add water to the soil and mix it with mechanical devices.

4)Temping:

Add as much water as needed to the the soil and mix the soil homogeneously.

We uses manual method for low content of soil. In large content we use pug mill machine for mixing of soil.

The pug mill is made of a conical cylindrical vessel with a diameter higher than that of the bottom.  An estimated 1/3 height of pugmill is place in the ground.  In the center is an upright shaft on which many horizontal arms are fitted and a vertical cutting blaze is attached to these horizontal arms.  When the vertical shaft is rotated with power, the arms also rotate with the shaft.  Water sprayed soil is inserted into the machine from the top.  After a short time of shaft moves, the mixed soil is taken out from the bottom.

Making of bricks from clay/soil.

Their are three way of making bricks from clay.

1)Ground moulding
2)Table moulding
3)Machine moulding

1)Ground Moulding

Fine sand is place over plastered surface on ground. Molding bricks are submerge in the in water for few minutes so that clay dont stick with mould.  Instead of submerging the mold in water, a straight and sharp edged brick can be constructed if sand or fly ash is sprayed on the inside of it.  The bricks thus formed are called sand moulded bricks.

The clay is forced into mould and fully press at corners so that there is no cavity on the corners.  Extra clay is removed from the striker. The moulded bricks are lifted so that bricks are form.

2) Table Moulding

The method for molding brick is the same as mentioned above. Molding is done on the table instead of the ground.

3)Machine Moulding

When a large amount of bricks is needed, the molding of bricks done by mechanical means. Mechanical molding allows bricks to be moulded  to the required number of good quality bricks.

Burning of brick

Their are various way to burn brick.

1)Burning of bricks in Clamps

Combustion of low bricks is done clamp.  Nearby materials such as dung, coriander, leaves, branches, wood etc. can be used for fuel in burning.

Frist fuel level is place at the bottom of height 70cm in incline position.The layers of three to four bricks are arranged in such a way that the air can be transposed on the sides of the bricks, then the fuel level is again laid, thus simultaneously raising the fuel and brick layers to a height of 3 to 4 meters.

2)Burning of bricks in intermittent kilns.

Generally shape of intermittent kilns is rectangular. Wood,coal, agriculture waste are used as a fuel. Short walls of bricks are place between fuel.

Good quality of brick optain.

3) Continuous kilns

Process is as shown in figure.

This process is used when supply of bricks is countinous.

Point A- Bricks are load
Point B- Pre heating of bricks
Point C- Burning of Bricks
Point D-Cooling of bricks
Point E-Unloading of bricks.

Thier are two type of of Countinous kilns.

1)Bull trench kilns
2)Hoffman’s Kilns

1)Bull Trench Kilns

Point A,F:- Pre Heating of bricks
Point B,G:- Burning of bricks
Point C,H:- Cooling of bricks
Point D,I:- Unloading of brick in kiln
Point E,J :- Loading of brick in kiln

2)Hoffman’s Kiln

This type of kilns are in circular shape. At the centre chimney is provided. The circular section is divided in 12 parts.Holes are provided at the top of slab for fuel.

Point 1,12:-Cooling Air is Inserted/Unloading of bricks.
Point 11,10,9,8:-Cooling of bricks gradually.
Point 6,7  :-Burning of bricks
Point 5,4,3:- Pre heating of bricks
Point 2 :- Loading of brick