- Brick is one of the oldest building materials, it continues to be the most popular and leading construction material.
Table of Contents
SIZE OF BRICKS:-
- Standard size of Bricks (modularize)=19cm x 9cm x 9cm
- Nominal size of Bricks (with mortar) = 20cm x 10cm x 10cm
- Conventional size of Bricks = 23cm x 11.4cm x 7.6cm
Classification of bricks
- First class bricks
- Thoroughly burnt, deep red, cherry or
copper colour. - Smooth, rectangular surface, sharp and straight edges.
- maximum Water absorption 20% of its dry weight when immersed in cold water for 24 hours
- Crushing strength – should not be less than 10N/mm
- USES:- Used for exposed face work in masonry, flooring, and Ranford brickwork.
- Second class brick
- Small racks and distortions permitted
- Water absorption– 22 % of its dry wt.
- Cushing strength– should not be less than
- Uses– second class bricks are recommended for all unimportant hidden masonry works
PROPERTIES | 1ST CLASS BRICK | 2ND CLASS BRICK | 3RD CLASS BRICKS | 4TH CLASS BRICK |
COLOR | Deep red cherry or copper color | Uniform red | Pale yellow color as this under burnt | Dark red, bluish color. As this over burnt |
WATER ABSORPTION | 20% of dry weight | 22% of dry weight | 25% of dry weight | More than 25 % of dry weight |
CRUSHING STRENGTH | Minimum crushing strength 10N/mm2 | 7.0N/mm2 | Less then 7.0 | 5.0N/mm2 |
ABRASION | No impression should be left on a brick when scratched with a nail | No impression | Impression present | Impression is present |
IMPACT RESISTANCE | Should not break into pieces when dropped from a height of 1.0 meter | Should not break | break | break |
SOUNDNESS | Brick should not break and produce a clear ringing sound when struck with each other. | Brick should not break & produce a clear ringing sound | Dull sound | Brick break easily & produce a dull sound |
USES | For pointing, exposed masonry work | Used for hidden masonry work | For temporary structure | Used as ballast in lime concrete |
CHARACTERISTICS OF GOOD BRICKS
- Size and shape – uniform size, rectangular surface with parallel sides and sharp straight edges
- Color – uniform deep red color indicative of uniformity in chemical composition and thoroughness in burning
- Hardness & soundness – The brick should be so hard that when scratched by a fingernail, no impression is made. When two bricks stuck together, a metallic sound should be produced
- Impacts:- Brick should not break into the piece when – dropped from a height of 1.0 meter
- Water absorption – should not exceed 20 % of its dry weight when kept immersed in
water for 24 hours. - Crushing strength:- Should not be less than 10N/mm2
- Bricks earth:- should be free from stones, kantars, organic matter.
Ingredients of good brick earth
- Silica – 50 – 60 % – Prevents shrinkage and warping. excess of silica makes the brick brittle
- Alumina – 20 – 30 % – Provide plasticity to bricks earth. excess of alumina produce
- cracks on drying bricks
- Lime – 10 %- Reduces shrinkage, helps in a fusing of silica and alumina
- Ferric oxide < 7 % -Reddish tinge to brick, give strength and hardness,
- Magnesia < 1 % – magnesia gives a yellowish tinge to be bricks
- Alkalis – < 10 % – excess of alkali cause efflorescence
The function of various Ingredients of Brick earth
- SILICA ( 50 – 60 ) %
- It enables the brick to retain its shape and import durability.
- It prevents shrinkage and warping
- The excess of silica makes the bricks brittle and weak on burning.
- ALUMINA (20 – 30 ) %
- It absorbs water and renders the clay plastic.
- If alumina is present in excess of a specified quantity, it produces cracks in brick on drying
- Lime (10%)
- reacts with silica during burning and thus helps to bind it.
- Magnesia (< 1%)
- gives yellowish tings to brick
- Iron oxide (< 7 %)
- give reddish tings to bricks
- gives strength and hardness improves impermeability & durability
Harmful substance in brick earth
Lime: the appropriate quantity of lime outcomes in correct bricks:- however if lime is found in lumps, it absorbs moisture swells and reasons the disintegration of the bricks.
:- lime must be found in finely divided slots & lumps if any must be eliminated in starting itself.
- Pebbles, grovels, grits:- do not allow the clay to mixed thoroughly and spoil the appearance of brick.
- Iron pyrites:- tend to oxidize and decompose the brick burning, pyrites decolorize the brick
- Alkalies:- forming less than 10% of row clay, are of great value as fluxes
- mainly present in the form of soda or potash
- alkalies absorb moisture when bricks come in contact with moisture, on drying moisture evaporates leaving behind grey or white powder deposits
- Organic matter:- If left in bricks, undergoes decomposition over a period of time, resulting in the formation of gases, escape of gases making brick porus
The manufacturing process of bricks
- Unsoiling:- Top 20 cm of soil is removed because it contains high organic matter.
- Digging:- After removing the top 20 cm of soil, the remaining soil is dug out and spread over the level field.
- Cleaning:- is the process of removal of impurities from the soil i, e. organic matters, stones, pebbles, etc.
- Weathering:– cleaned soil left in heap and exposed to the atmosphere for at least one month. This is done to develop – homogeneity in the mass of soil, particularly if they are from different sources.
- Blending:- clay is made loose and any ingredient – deficiency spread over it.
- Tampering:- water is added in clay in order to bring it up to req. Plasticity is required. for the next operation of molding. Kneading the brick earth
Frog (indentation mark )
Purpose – act as a key for mortar
- provide lateral stability to brick
3. Drying – is done either naturally or artificially.
- the water content of brick is reduced up to 2.0% so that energy consumption during the burning process reduces.
- during drying bricks must be placed along the edges, not along the surface, so that maximum surface area exposed to the atmosphere.
4. Burning – temp. is (900 – 1200)
EFFLORESCENCE IN BRICKS
IS:- 3495 – Liability of efflorescence will be mentioned as nil, slight, moderate, heavy or serious.
(a) Nil- When there is no perceptible deposit of efflorescence
(b) Slight – When not more then 10 percent of the exposed area of the brick is covered with a thin deposit of salts
(c) Moderate:-when there’s a heavier deposit then below mild and protecting much as 50% of the uncovered place of the brick floor however unaccompanied through powdering or flaking of the floor.
(d) Heavy:- when there is a heavy deposit of salts covering 50 % or more of the exposed areas but unaccompanied by powdering or flaking of the surface.
(e) Serious:- when there are heaving deposits of salts accompanied by powdering or flaking of exposed surfaces.
Notes;- – wt. of 1 m3 of brick is approximately = 1800 kg
- wt. of 1 brick is (3 – 3.5)Kg
- 1m3 = 500 – 550 Brick
Other types of brick
Perforated bricks
- Small holes may exceed 25 percent of the total volume of the brick
- Lighter in weight & provides insulation against heat, due to voids present in it.
Autoclave Bricks
- has less water absorption compared to other bricks
- Noise reduction
- Autoclave bricks are bricks cured in pressurized steam,
- bricks got cured in less than 10 hours as compared to over 10 days.
Refractory Bricks
- are those bricks providing resistance against decomposition of brick due to chemical action, high temperature, Dampness
- Compressive strength of this bricks various from Types – acid bricks
- Basic bricks – Magnesite, Mullite, carbon & basic ramming brick.
- Neutral bricks
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