1. BRICKS

2. 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
replace stones

3. Jetavanaramaya stupa in Anuradhapura, Sri Lanka is one of the largest brick structures in the world.

4. The world's highest brick tower of St
The world's highest brick tower of St. Martin's Church in Landshut, Germany, completed in 1500

5. The brickwork of Shebeli Tower in Iran displays 12th century craftsmanship
Chile house in Hamburg, Germany

6. Size of Brick used Size of the Brick Standard size 19cm X 9cm X 9cm
Nominal size 20cm X 10cm X 10cm
Nominal size is the thikness of motar with brick size

7. CLASSIFICATION OF BRICKS
First class bricks:
These bricks are table-moulded and of standard shape and they are burnt in kilns.
The surfaces and edges of the bricks are sharp, square, smooth and straight.
These bricks are used for superior work of permanent nature.

8. Second class bricks:
are ground-moulded and they are burnt in kilns.
The surface of these bricks is somewhat rough and shape is also slightly irregular.
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

9. Third class bricks:
ground-moulded and they are burnt in clamps.
not hard and they have rough surfaces with irregular and distorted edges.
give dull sound when struck together.
used for unimportant and temporary structures and at places where rainfall is not heavy.

10. Fourth class bricks:
These are over burnt with irregular shape and dark color.
These bricks are used as aggregate for concrete in foundations, floors, roads, etc.
the over burnt brick have a compact structure ----sometimes found to be stronger that even the first class bricks.

11. Composition Following are the constituents of good brick earth.
Alumina
chief constituent of clay
A good brick earth should contain 20 to 30 percent of alumina.
imparts plasticity to earth moulded.
If alumina is present in excess, raw bricks shrink and warp during drying and burning.

12. 2. Silica
A good brick earth should contain about 50 to 60 percent of silica.
Silica exists in clay either as free or combined form.
Presence of silica prevents crackers, shrinking and warping of raw bricks.
It thus imparts uniform shape to the bricks.

13. 3. Lime
A small quantity in finely powdered state prevents shrinkage of raw bricks.
Excess of lime causes the brick to melt and hence, its shape is lost due to the splitting of brick

14. 4. Oxide of iron
A small quantity of oxide of Iron -- 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.

15. 5. Magnesia
A small quantity of magnesia in brick earth imparts yellow tint to bricks
decreases shrinkage.
excess of magnesia leads to the decay of bricks.
The ingredients like, lime, alkalies, pebbles, organic matter should not present in good brick earth

16. Manufacture of bricks:
The manufacturing of brick, the following operations are involved
Site selection
Preparation of brick earth
Moulding of brick
Drying of bricks
Burning of bricks
Unsoiling
Digging
Cleaning
Weathering
Grinding
Blending
Tempering

17. Selection of site
Must have suitable clay
In sufficient quantity
Location---water table should be atleast 1m below kiln floor

18. (ii) Preparation of clay :-
The preparation of clay involvesfollowing operations
Unsoiling
Top layer of 20cm depth is removed as it contain impurities-organic matter, roots.
Digging
Clay is dug out from ground and spread on level ground about 60cm to 120cm heaps.
Cleaning
Stones, pebbles, vegetable matter etc removed and converted into powder form.

20. Weathering
Clay is exposed to atmosphere from few weeks to full season.
Grinding
hard clay with lumps are crushed in clay crushing rollers
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
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,
done in pug mill

22. iii) Moulding of bricks Hand or machine Mould- Rectangular boxes open at bottom Wood or steel

23. Hand moulding
Ground is levelled
Sprinkle fine sand
Dip mould in water and place on grnd
Lumps of clay are dashed in to it
Pressed and filled----fill corners
Surplus clay removed by using a stricker
Mould is lifted up
Raw brick remains

25. Machine moulding
When,
-large scale production
Clay is hard
Plastic clay machine---wire cut bricks
Dry clay machine---powdered clay filled in moulds ---pour water----pressed----results in hard, well shaped

26. Drying
The damp bricks, if burnt, are likely to be cracked and distorted.
Hence moulded bricks are dried
Bricks are laid along and across the stock in alternate layers.
5-7 % moisture content
Mostly natural or artificial drying

27. Burning:
to impart hardness, strength and makes them dense and durable.
Burning --- clamps or in kilns.
Clamps are temporary structures and to manufacture bricks on small scale.
Kilns are permanent structures and they are adopted to manufacture bricks on a large scale.

30. Clamp
Temporary structures
Stacked in layers with gaps for firewood
6-8 weeks
Strong tough bricks
Quality not uniform
No skilled labour
Kilns
Masonry structures ----permanent
Continuous
Uniform quality
Need skilled labour

31. Qualities of Good Brick
Bricks should be table moulded,
well burnt in kilns, copper coloured,
free from cracks and
with sharp and square edges
uniform shape and should be of standard size
clear ringing sound when struck each other

32. bright homogeneous and compact structure free from voids
should not absorb water more than 20 percent by weight for first class bricks
22 percent by weight for second class bricks
when soaked in coldwater for a period of 24 hours

33. Tests on bricks
A brick is generally subjected to following tests to find out its suitability of the construction work.
Compressive strength
Absorption
Hardness
Presence soluble salts
Shape and size
Soundness
Structure
A good should not absorb not more than 20 percent of weight of dry brick

34. Compressive strength:
Smooth the surface, immerse in water for 24 hrs
in compression testing machine
It is pressed till it 14 N/mm2 per minute
Compr strength = max load at failure/loaded area of brick

35. Absorption
Oven dried for C
270 C for 24 hrs
A good should not absorb not more than 20 percent of weight of dry brick  
%water absorption = ((w2-w1)/w1) X 100
Hardness
Scratch with finger nail -- No impression is left on the surface the brick is treated to be sufficiently hard

36. Presence of soluble salts (efflorescence)
The bricks should not show any grey or white deposits after immersed in water for 24 hours (HW)
Shape and size
It should be standard size and shape with sharp edges

37. Soundness
The brick should give clear ringing sound struck each other
Structure
The structure should be homogeneous, compact and free from any defects

38. Measure greatest distance using the rule
Warpage
Measured with
Flat surface of steel/glass
Steel measuring rule
Clean the surface
Place on the flat
Measure greatest distance using the rule

39. Thank you