Short Notes: Bricks | Short Notes for Civil Engineering - Civil Engineering (CE) PDF Download

 Page 1


CHAPTER-2 
BRICKS 
Bricks are obtained by moulding clay in rectangular blocks of uniform 
size and then by drying and burning these blocks. As bricks are of 
uniform size, they can be properly arranged, light in weight and hence 
bricks replace stones. 
2.1 Composition - Manufacture Process. 
Composition – Following are the constituents of good brick earth. 
Alumina: - It is the chief constituent of every kind of clay. A good brick 
earth should contain 20 to 30 percent of alumina. This constituent 
imparts plasticity to earth so that it can be moulded. If alumina is present 
in excess, raw bricks shrink and warp during drying and burning. 
Silica-A good brick earth should contain about 50 to 60 percent of silica. 
Silica exists in clay either as free or combined form. As free sand, it is 
mechanically mixed with clay and in combined form; it exists in 
chemical composition with alumina. Presence of silica prevents crackers 
shrinking and warping of raw bricks. It thus imparts uniform shape to the 
bricks. Durability of bricks depends on the proper proportion of silica in 
brick earth. Excess of silica destroys the cohesion between particles and 
bricks become brittle. 
Lime – A small quantity of lime is desirable in finely powdered state to 
prevents shrinkage of raw bricks. Excess of lime causes the brick to melt 
and hence, its shape is last due to the splitting of bricks. 
Page 2


CHAPTER-2 
BRICKS 
Bricks are obtained by moulding clay in rectangular blocks of uniform 
size and then by drying and burning these blocks. As bricks are of 
uniform size, they can be properly arranged, light in weight and hence 
bricks replace stones. 
2.1 Composition - Manufacture Process. 
Composition – Following are the constituents of good brick earth. 
Alumina: - It is the chief constituent of every kind of clay. A good brick 
earth should contain 20 to 30 percent of alumina. This constituent 
imparts plasticity to earth so that it can be moulded. If alumina is present 
in excess, raw bricks shrink and warp during drying and burning. 
Silica-A good brick earth should contain about 50 to 60 percent of silica. 
Silica exists in clay either as free or combined form. As free sand, it is 
mechanically mixed with clay and in combined form; it exists in 
chemical composition with alumina. Presence of silica prevents crackers 
shrinking and warping of raw bricks. It thus imparts uniform shape to the 
bricks. Durability of bricks depends on the proper proportion of silica in 
brick earth. Excess of silica destroys the cohesion between particles and 
bricks become brittle. 
Lime – A small quantity of lime is desirable in finely powdered state to 
prevents shrinkage of raw bricks. Excess of lime causes the brick to melt 
and hence, its shape is last due to the splitting of bricks. 
Bricks                                                                
  
 
Oxide of iron- A small quantity of oxide of Iron to the extent of 5 to 6 
percent is desirable in good brick to imparts red colour to bricks. Excess 
of oxide of iron makes the bricks dark blue or blackish. 
Magnesia- A small quantity of magnesia in brick earth imparts yellow 
tint to bricks, and decreases shrinkage. But excess of magnesia decreases 
shrink leads to the decay of bricks. 
 The ingredients like, lime, iron pyrites, alkalies, pebbles, organic 
matter should not present in good brick earth  
Manufacture of bricks: 
The manufacturing of brick, the following operations are involved 
1. Preparation of clay 
2. Moulding 
3. Drying 
4. Burning 
(i) Preparation of clay :- The preparation of clay involves 
following operations 
a) Unsoiling :- Top layer of 20cm depth is removed as it contain 
impurities.  
 
Page 3


CHAPTER-2 
BRICKS 
Bricks are obtained by moulding clay in rectangular blocks of uniform 
size and then by drying and burning these blocks. As bricks are of 
uniform size, they can be properly arranged, light in weight and hence 
bricks replace stones. 
2.1 Composition - Manufacture Process. 
Composition – Following are the constituents of good brick earth. 
Alumina: - It is the chief constituent of every kind of clay. A good brick 
earth should contain 20 to 30 percent of alumina. This constituent 
imparts plasticity to earth so that it can be moulded. If alumina is present 
in excess, raw bricks shrink and warp during drying and burning. 
Silica-A good brick earth should contain about 50 to 60 percent of silica. 
Silica exists in clay either as free or combined form. As free sand, it is 
mechanically mixed with clay and in combined form; it exists in 
chemical composition with alumina. Presence of silica prevents crackers 
shrinking and warping of raw bricks. It thus imparts uniform shape to the 
bricks. Durability of bricks depends on the proper proportion of silica in 
brick earth. Excess of silica destroys the cohesion between particles and 
bricks become brittle. 
Lime – A small quantity of lime is desirable in finely powdered state to 
prevents shrinkage of raw bricks. Excess of lime causes the brick to melt 
and hence, its shape is last due to the splitting of bricks. 
Bricks                                                                
  
 
Oxide of iron- A small quantity of oxide of Iron to the extent of 5 to 6 
percent is desirable in good brick to imparts red colour to bricks. Excess 
of oxide of iron makes the bricks dark blue or blackish. 
Magnesia- A small quantity of magnesia in brick earth imparts yellow 
tint to bricks, and decreases shrinkage. But excess of magnesia decreases 
shrink leads to the decay of bricks. 
 The ingredients like, lime, iron pyrites, alkalies, pebbles, organic 
matter should not present in good brick earth  
Manufacture of bricks: 
The manufacturing of brick, the following operations are involved 
1. Preparation of clay 
2. Moulding 
3. Drying 
4. Burning 
(i) Preparation of clay :- The preparation of clay involves 
following operations 
a) Unsoiling :- Top layer of 20cm depth is removed as it contain 
impurities.  
 
 
b) Digging: - Clay dug out from ground is spread on level 
ground about 60cm to 120cm heaps. 
c) Cleaning:-Stones, pebbles, vegetable matter etc removed and 
converted into powder form. 
d) Weathering:- Clay is exposed to atmosphere from few weeks 
to full season. 
e) Blending:- Clay is made loose and any ingradient to be added 
to it is spread out at top and turning it up and down in vertical 
direction. 
f) Tempering:- Clay is brought to a proper degree of hardness, 
then water is added to clay and whole mass is kneaded or 
pressed under the feet of men or cattle for large scale, 
tempering is usually done in pug mill as shown in the fig 2.1 
Page 4


CHAPTER-2 
BRICKS 
Bricks are obtained by moulding clay in rectangular blocks of uniform 
size and then by drying and burning these blocks. As bricks are of 
uniform size, they can be properly arranged, light in weight and hence 
bricks replace stones. 
2.1 Composition - Manufacture Process. 
Composition – Following are the constituents of good brick earth. 
Alumina: - It is the chief constituent of every kind of clay. A good brick 
earth should contain 20 to 30 percent of alumina. This constituent 
imparts plasticity to earth so that it can be moulded. If alumina is present 
in excess, raw bricks shrink and warp during drying and burning. 
Silica-A good brick earth should contain about 50 to 60 percent of silica. 
Silica exists in clay either as free or combined form. As free sand, it is 
mechanically mixed with clay and in combined form; it exists in 
chemical composition with alumina. Presence of silica prevents crackers 
shrinking and warping of raw bricks. It thus imparts uniform shape to the 
bricks. Durability of bricks depends on the proper proportion of silica in 
brick earth. Excess of silica destroys the cohesion between particles and 
bricks become brittle. 
Lime – A small quantity of lime is desirable in finely powdered state to 
prevents shrinkage of raw bricks. Excess of lime causes the brick to melt 
and hence, its shape is last due to the splitting of bricks. 
Bricks                                                                
  
 
Oxide of iron- A small quantity of oxide of Iron to the extent of 5 to 6 
percent is desirable in good brick to imparts red colour to bricks. Excess 
of oxide of iron makes the bricks dark blue or blackish. 
Magnesia- A small quantity of magnesia in brick earth imparts yellow 
tint to bricks, and decreases shrinkage. But excess of magnesia decreases 
shrink leads to the decay of bricks. 
 The ingredients like, lime, iron pyrites, alkalies, pebbles, organic 
matter should not present in good brick earth  
Manufacture of bricks: 
The manufacturing of brick, the following operations are involved 
1. Preparation of clay 
2. Moulding 
3. Drying 
4. Burning 
(i) Preparation of clay :- The preparation of clay involves 
following operations 
a) Unsoiling :- Top layer of 20cm depth is removed as it contain 
impurities.  
 
 
b) Digging: - Clay dug out from ground is spread on level 
ground about 60cm to 120cm heaps. 
c) Cleaning:-Stones, pebbles, vegetable matter etc removed and 
converted into powder form. 
d) Weathering:- Clay is exposed to atmosphere from few weeks 
to full season. 
e) Blending:- Clay is made loose and any ingradient to be added 
to it is spread out at top and turning it up and down in vertical 
direction. 
f) Tempering:- Clay is brought to a proper degree of hardness, 
then water is added to clay and whole mass is kneaded or 
pressed under the feet of men or cattle for large scale, 
tempering is usually done in pug mill as shown in the fig 2.1 
Bricks                                                                   
  
 
Fig 2.1  Pug Mill 
Process:- Clay with water is placed in pug mill from the top. When the 
vertical staff is rotated by using electric pair, steam or diesel or turned by 
pair of bullocks. Clay is thoroughly mixed up by the actions of 
horizontal arms and knives when clay has been sufficiently pugged, hole 
Page 5


CHAPTER-2 
BRICKS 
Bricks are obtained by moulding clay in rectangular blocks of uniform 
size and then by drying and burning these blocks. As bricks are of 
uniform size, they can be properly arranged, light in weight and hence 
bricks replace stones. 
2.1 Composition - Manufacture Process. 
Composition – Following are the constituents of good brick earth. 
Alumina: - It is the chief constituent of every kind of clay. A good brick 
earth should contain 20 to 30 percent of alumina. This constituent 
imparts plasticity to earth so that it can be moulded. If alumina is present 
in excess, raw bricks shrink and warp during drying and burning. 
Silica-A good brick earth should contain about 50 to 60 percent of silica. 
Silica exists in clay either as free or combined form. As free sand, it is 
mechanically mixed with clay and in combined form; it exists in 
chemical composition with alumina. Presence of silica prevents crackers 
shrinking and warping of raw bricks. It thus imparts uniform shape to the 
bricks. Durability of bricks depends on the proper proportion of silica in 
brick earth. Excess of silica destroys the cohesion between particles and 
bricks become brittle. 
Lime – A small quantity of lime is desirable in finely powdered state to 
prevents shrinkage of raw bricks. Excess of lime causes the brick to melt 
and hence, its shape is last due to the splitting of bricks. 
Bricks                                                                
  
 
Oxide of iron- A small quantity of oxide of Iron to the extent of 5 to 6 
percent is desirable in good brick to imparts red colour to bricks. Excess 
of oxide of iron makes the bricks dark blue or blackish. 
Magnesia- A small quantity of magnesia in brick earth imparts yellow 
tint to bricks, and decreases shrinkage. But excess of magnesia decreases 
shrink leads to the decay of bricks. 
 The ingredients like, lime, iron pyrites, alkalies, pebbles, organic 
matter should not present in good brick earth  
Manufacture of bricks: 
The manufacturing of brick, the following operations are involved 
1. Preparation of clay 
2. Moulding 
3. Drying 
4. Burning 
(i) Preparation of clay :- The preparation of clay involves 
following operations 
a) Unsoiling :- Top layer of 20cm depth is removed as it contain 
impurities.  
 
 
b) Digging: - Clay dug out from ground is spread on level 
ground about 60cm to 120cm heaps. 
c) Cleaning:-Stones, pebbles, vegetable matter etc removed and 
converted into powder form. 
d) Weathering:- Clay is exposed to atmosphere from few weeks 
to full season. 
e) Blending:- Clay is made loose and any ingradient to be added 
to it is spread out at top and turning it up and down in vertical 
direction. 
f) Tempering:- Clay is brought to a proper degree of hardness, 
then water is added to clay and whole mass is kneaded or 
pressed under the feet of men or cattle for large scale, 
tempering is usually done in pug mill as shown in the fig 2.1 
Bricks                                                                   
  
 
Fig 2.1  Pug Mill 
Process:- Clay with water is placed in pug mill from the top. When the 
vertical staff is rotated by using electric pair, steam or diesel or turned by 
pair of bullocks. Clay is thoroughly mixed up by the actions of 
horizontal arms and knives when clay has been sufficiently pugged, hole 
at the bottom of tub, is opened cut and the pugged earth is taken out from 
ramp for the next operation of moulding. 
Moulding: Clay, which is prepared form pug mill, is sent for the next 
operation of moulding. Following are the two ways of moulding. 
Hand Moulding: Moulds are rectangular boxes of wood or steel, which 
are open at top and bottom. Steel moulds are more durable and used for 
manufacturing bricks on large scale as shown in fig 2.2. Bricks prepared 
by hand moulding are of two types. 
 
Fig 2.2 Wooden mould & Steel mould 
a) Ground moulded bricks 
b) Table moulded bricks 
(a) Ground moulded bricks: ground is first made level and fine sand is 
sprinkled over it. Mould is dipped in water and placed over the 
ground to fill the clay. Extra clay is removed by wooden or metal 
strike after the mould is filled forced mould is then lifted up and raw