Quick Revision of Bricks
Building material Civil engineering
Brick is one of the oldest building material used by us because of its durability, strength, reliability, low cost and easy availability etc.
Contents
- Size of Bricks
- About Bricks
- Composition of good Brick Earth
- Classification of Bricks
- Manufacturing of Brick
- Types of Burning of Brick
- Types of kiln used for manufacturing of Bricks
- Defects in Brick
- Test on Bricks
- Special Type of Bricks
- As per IS 1077: 1992, clause 7.3
- Type of Fire Bricks
- Tolerances limit of Bricks
- Test on Brick Earth
Quick Revision of Bricks Study
SIZE OF BRICKS
size
composition
classification
Quick Revision of Bricks Study
Quick Revision of Bricks Study>
| Brick | breadth | width | depth |
|---|---|---|---|
| Nominal size brick | 20 cm | 10 cm | 10 cm |
| Modular size brick | 19 cm | 9 cm | 9 cm |
| Standard size brick | 19 cm | 9 cm | 9 cm |
| Non standard brick or Traditional brick or Field brick or Conventional brick |
23 cm | 11.4 cm | 7.6 cm |
| size of frog | 10 cm | 4 cm | 1 to 2 cm |
Quick Revision of Bricks Study
| No. | 1. | 2. | 3. |
|---|---|---|---|
| No of bricks | 500 | on one cubic meter | |
| Purpose of Frog providing | to help | bonding between brick and mortar | a |
| weight of one brick | in kg | 3 to 3.5 kg | a |
| unit weight of one brick | in kg/cu m | 19 KN/m3 | a |
| a |
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Composition of good Brick Earth
| composition | in percent | properties contribution | property on excess |
|---|---|---|---|
| Silica | 50-60% | retaining the shape of brick prevent cracking, shrinkage, warping of raw brick | destroy the cohession between particles and make brick brittle |
| Alumina | 20-30% | plasticity to brick | weak and warp on drying of brick |
| Lime | 10% | prevent shrinkage on drying | melt and brick loose its shape |
| Iron Oxide | <7% | gives red color helps lime to fuse with sand | dark blue color |
| manganese oxide | <1% | yellow tint color decrease shrinkage | decay of brick |
| sulphur oxide carbon dioxide | very small | spongy, swollen structure in the brick decolored by white blotches | |
water | very small | ||
| Note | good clay for making the brick is weathered clay. | ||
| Alkalies | very small | melt and loose their shape | |
| Organic matter | none | after burning leaving pores and make brick porous | |
| Pebbles, Gravels, Grits | lesser | weak and porous not give uniformity during mixture | |
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Classification of Bricks
| properties |
class 1st |
class 2nd |
class 3rd |
|---|---|---|---|
| water absorption | should not greater than 20% | should not greater than 22.5% | should not greater than 25% |
| compressive strength in N/mm2 | >10.5 | 7.5 | 5.5 |
| note | As per IS code 1077-1976 common building brick shall have minimum strength 3.5 N/mm2 water absorption for 1st class brick should be 12 to 15 % of its dry unit wt after 24 hour from emerged in water | ||
Manufacturing process of Brick
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Manufacturing process of Brick
Quick Revision of Bricks Study>
| Term | Process | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Unsoiling | top layer of soil upto depth of 20 cm throw away | ||||||||||||||||
Digging | clay is dug out after unsoiling from the ground and spreadon levelled ground the height of heaps of the clay is about 60 to 120 cm | ||||||||||||||||
Cleaning | free from stones, vegetable, other unimportant matters etc. | ||||||||||||||||
Weathering | exposed to atmosphere for softening to remove the various organic particles etc and for good stability | ||||||||||||||||
Blending | process of mixing clay, water and other ingredient to make the brick for kneading action | ||||||||||||||||
Tempering | mixing untill reach proper hardness suitable for moulding | ||||||||||||||||
Mounding | Give the Brick to its shape by Hand mounding AND Machine moulding size of mould are 8-12% larger area than the brick | ||||||||||||||||
Drying | drying in air from 3 to 8 days not in sun | ||||||||||||||||
Burning | 900 - 1200°C bricks should be properly burnt
| ||||||||||||||||
| Note | burning can be done by two ways clamp burning and kiln burning |
Quick Revision of Bricks StudyTypes of Burning in Bricks manufacturing process
| Factors | clamp Burning | Kiln buring |
|---|---|---|
Initial Cost | Very Low | Very high |
capacity | 20000 to 100000 at a time | avg 25000 bricks per day |
Quality | small approx 60% | 85 to 90% |
| Time | 2 to 6 month | 24 hour for 1 brick and it takes 12 days for cooling |
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Types of kiln used for manufacturing of Bricks
| Action | Bull trench Kiln | Hoffman Kiln |
|---|---|---|
Type | Semi continuous | Perfectly Continuous |
Burning Capacity | 3 lac in 12 days | 40 lac in 1 season |
| Note | both kiln is type of pugmill | |
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Test on Bricks
| Test | Specification | IS codes | Used for | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Dimension Test | Dimension should not greater than below value Length -19×20= 380 ± 12 cm Breadth - 9×20 = 180 ± 6 cm Height - 9×20 = 180 ± 6 cm here 20 indicate 20 no of bricks used in sample | IS 1077 | determining shape | ||||||||||||
Water absorption Test | average water absorption should not be more than 20% by weight and class M125 - 12.5 N/mm2 and 15% by weight for higher | IS 3495 part 2 | detemining water absorption capacity | ||||||||||||
Effloresence Test | It is divided into following types on the basis of area of effected by effloresence
| IS 3495 part 3 | used for determining appearance | ||||||||||||
Compressive Strength Test | for common brick >3.5 N/mm2 or 35 kg/cm2 first class 10.5 second class 7.5 and third class 5.5 | IS 3495 part 1 | |||||||||||||
Warpage Test | concave warpage convex warpagee it is determined with the help of glass or steel sufrace | IS 3495 part 4 |
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Defects in Bricks
| No | Type | Description | cause |
|---|---|---|---|
| 1. | Chuffs | Deformation of shape of brick | Due to rain water falling on the hot surface of brick |
| 2. | Bloating | spongy swells over the surface of burnt bricks | excess carbonaceous matter present on brick earth like alkalies |
| 3. | Over-Burnt | Soft molten mass is produced and bricks loose their shape not suitable for construction work | Bricks are over burn. |
| 4 | under-burnt | Higher degree of water absorption and less compressive strength not suitable for construction work | due to not properly burnt, clay is not softened because of insufficient heat. |
| 5. | Black Core | Seen black core | mainly because of improper burning due to presence of bituminous matter or carbon and they are not completely removed by oxidation |
| 6. | Efflorescence | Grey or white patches are seen after drying of brick or after contact of moisture | alkalies present in brick earth reduced by proper selection of clay material. |
| 7. | Checks or Crackes | expansion of brick after contact with moisture and disintegration of brick, results shrinkage and burning cracks | Presence of lumps of bricks or excess of water used during manufactured of bricks |
| 8. | Spots | Dark Surface spot on brick surface. | Presence of sulphide |
| 9. | Blisters  | show blister on surface of brick | Air imprisoned during their moulding |
| 10. | Lamination | Seen thin lamina on the brick faces which weathered out on exposure weak in surface | entrapped air in the voids of clay |
Special Type of Bricks
| No | Type | IS Code | Description |
|---|---|---|---|
| 1. | Heavy Duty Burnt Clay Bricks <C.S. = not less than 440kg/cm2> | IS:2180 <IMP> | similar to burnt clay bricks and of same size but with high compressive strength free from cracks, flaws and nodules of free base Uses in heavy engineering work such as bridge and industrial foundation and multi-storey building Two types- class 400 and class 450 400 indicate compressive strength in 40N/mm2 Bulk density <2500 kg/m3 Efflorescence - Nill Water absorption - < 10% |
2. | Burnt Clay Perforated Brciks | IS:2222 | have Cylindrical holes throughout theier thickness, have high compressive strength less water absorption area of perforation should not exceed 30 to 45%area of face |
3. | Burning clay Facing Bricks | IS:2691 | used without any further protection of faces of wall used in corrosive environment and high rise building it is economical class 1 - >100 kg/cmm2 class 2 - >75 kg/mm2 availabe on two sizes 19×9×9 cm and 19×9×4 cm |
4. | Burnt Clay paving Bricks | IS:3583 | Iron content more than ordinary brick this cause vitrification of bricks burning at low temperature which give natural glaze to brick and more resistant to abrasion |
5. | Burnt Clay Soiling Bricks | IS:5779 | Compressive strenth >5.0 N/mm2 Water absorption < 20 % Efflorescence - slight |
6. | Burnt clay Hollow Blocks | IS:3962 | these blocks also known as cellular or cavity blocks used to reduce the dead weight of masonry reduce the transmission of heat, sound and dampness Crushing strength >3.5 N/mm2 Water absorption < 20 % |
7. | Sand Lime Bricks | IS:4139 | also known as silicate bricks crushed siliceous rock and lime combined by the action of saturated steam under pressure |
8. | Sewer Bricks | IS:44885 | manufactured from surface clay, fine clay or shale used for lining of walls, roofs and floor of severs average compressive strength > 175 kg /mm2 water absorption <12% |
9. | Acid Resistant Bricks | IS:4860 | Resistant to acid and base |
10. | Refractory Bricks/Fire clay Bricks | IS:4860 | Resist high temperature up 1700 °C |
As per IS 1077: 1992, clause 7.3,
The rating of efflorescence shall not be more than 'moderate' up to class 12·5 and 'slight' for classes higher than 12.5.
The common burnt clay bricks shall be classified on the basis of average compressive strength as given by
Class designation Avg compressive strength not less than (N/mm2)
35 35
30 30
25 25
20 20
17.5 17.5
15 15
12.5 12.5
10 10
7.5 7.5
5 5
3.5 3.5
Types of Bricks based on uses during masonry
(a) Bevelled closer
(b) Queen-closer(half)
(c) Queen-closer(quarter)
(c) Queen-closer(quarter)
(d) King closer
(e) Full brick
(f) Mitred closer
(g) Half bat
(h) Three quarter bat
(i) Bevelled bat
What is the maximum allowable water absorption (%) of Indian burnt brick of class 20?
a. 15
b. 5
c.20
d.10
answer a. 15%
As per IS 1077: 1992, clause 7.2, Bricks after immersion in cold water for 24 hours, water absorption shall not be more than 20 percent by weight upto class 12.5 and for the classes above 12.5 water absorption shall be between 12.5 and 15 percent.
Note:
Water absorption for First class brick should not exceed 12-15 % of its dry weight.
comment if any doubt about first and second class brick water absorption
For second class brick it should be between 16 - 20%.
Type of Fire Bricks
The firebricks are classified on the basis of their reactivity or chemical change at high temperatures:
1. Basic Refractory Bricks:
- They are resistant to the melts of basic composition. Hence, they will not be suitable for use in those furnaces where acidic melts are being heated.
Examples:
- Magnesia bricks, Bauxite bricks.
2. Acid Refractory Bricks:
- They are resistant to the melts of acidic composition (but will react with the melts of basic composition).
Example:
- Fire-clay bricks, silica bricks.
3. Neutral Refractory Bricks:
- They are non-reactive to both the acidic and basic melts. Hence these find applications in heating either type of melts.
Examples:
- Chromite bricks, Chrome-magnesite bricks.
Tolerances limit of Bricks
As per IS 1077 (1992), clause 6.2, Tolerances
- The dimensions of bricks when tested in accordance with 6.2.1 shall be within the following limits per 20 bricks:
a) For modular size
- Length 3720 to 3880 mm (3800 ± 80 mrn)
- Width 1760 to 1840 mm (1800 ± 40 mm)
- Height 1760 to 1840 mm (1800 ± 40 mm)
- (For 90 mm high bricks)
- 760 to 840 mm (800 ± 40 mm)
- (For 40 mm high bricks)
b) For non - modular size 23 *11*7
- Length 4520 to 4680 mm (4600 ± 80 mm)
- Width 2240 to 2160 mm (2200 ± 40 mm)
- Height 1440 to 1360 mm (1400 ± 40 mm)
- (For 70 mm high bricks)
- 640 to 560 mm (600 ± 40 min)
- (For 30 mm high bricks)
Test on Brick Earth
- Ball of about 8 cm diameter are moulded with hands and allow it for sun dry. If the dry ball get deformed and crumble easily, it indicates that soil has sand particles in it.
- Well kneaded soil of plastic consistency which is capable of being rolled in threads of 3 mm in diameter. This test is done to determine shrinkage cracks.
English bond
In this bond, the alternate courses consist of headers and stretchers.
This is considered to be the strongest bond.
Hence it is a commonly used bond for walls of all thicknesses.
Flemish Bond
In this type of bond, each course comprises of alternate header and stretcher.
Alternate courses start with stretcher and header.
Every header is centrally supported on the stretcher below it.
Construction of Flemish bond needs greater skill.
Used to get a good aesthetic view.
To break the continuity of vertical joints
In English bond - Queen closer is used in the beginning and end of a wall after the first header.
In Flemish bond - Queen closers are required if a course starts with a header and in walls having their thickness equal to odd number of half bricks, bats are essentially used to achieve the bond.
In Header bond - 3/4 brick bat as a quoin brick in alternating courses.
Stretcher bond - 1/2 brick bat is provided in alternating courses.English bond
In this bond, the alternate courses consist of headers and stretchers.
This is considered to be the strongest bond.
Hence it is a commonly used bond for walls of all thicknesses.
Flemish Bond
In this type of bond, each course comprises of alternate header and stretcher.
Alternate courses start with stretcher and header.
Every header is centrally supported on the stretcher below it.
Construction of Flemish bond needs greater skill.
Used to get a good aesthetic view.
To break the continuity of vertical joints
In English bond - Queen closer is used in the beginning and end of a wall after the first header.
In Flemish bond - Queen closers are required if a course starts with a header and in walls having their thickness equal to odd number of half bricks, bats are essentially used to achieve the bond.
In Header bond - 3/4 brick bat as a quoin brick in alternating courses.
Stretcher bond - 1/2 brick bat is provided in alternating courses.
Angularity is a measure of angularity of aggregate sample. It gives a general idea of shape, void ratio, denseness, packaging and compactness of the aggregate sample.
Angularity Number = (67−W×100)/(w×G)
where
W = Aggregate weight filled in the cylinder
w = Weight of the water filled in the cylinder
G = specific gravity of aggregate
The angularity number ranges from 0 to 11 for aggregates suitable for making concrete.0
Important Points:
If the angularity number is zero, the solid volume of aggregate is 67% and if angularity number is 11, the solid volume of the aggregate is 56%. Angularity number represents the most practicable rounded aggregates and the angularity number 11 indicates the most angular aggregates that can be tolerated for making concrete which is not so unduly harsh and uneconomical.
Adulterants: Bariun sulphate, calcium carbonate, Magnesium silicate etc
Thinners: Petroleum, Spirit, naptha, turpentine oil
Driers: letharge, Cobalt, zinc
Bases: White lead, Red lead, aluminium powder.
Cement Mortar for Different Work | Proportion of Cement and sand in Mortar |
Cement mortar for normal brick work | 1:6 |
Cement mortar for plastering works | 1:4 |
Cement mortar for grouting the cavernous rocks | 1:1.5 |
Cement mortar for guniting | 1:3 |
Sir Abel's Process
- In this process, timber surface is cleaned and it is coated with a dilute solution of sodium silicate. A cream-like paste of slaked fat lime is then applied and finally, a concentrated solution of silicate of soda is applied on the timber surface. This process is quite satisfactory in making the timber fire- resistant.
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