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

**About Bricks**
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

**About Bricks**
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

Quick Revision of Bricks Study>

Composition of good Brick Earth

**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

Quick Revision of Bricks Study

Classification of Bricks

**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

- - - - - -

- - -

Manufacturing process of Brick
Quick Revision of Bricks Study>

Manufacturing of Bricks

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

Temp action during burning of Brick earth
stage	name	temperate	action
first	dehydration	400-650°C	Removal of water
second	oxidation	650-900°C	Removal of Carbon Compound
final	Vitrification	900-1200°C	Convert the mass into glass like substance

Note

burning can be done by two ways clamp burning
and kiln burning

Quick Revision of Bricks Study
Types of Burning in Bricks manufacturing process

Types 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

Quick Revision of Bricks Study

Types of kiln used for manufacturing of Bricks

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

Quick Revision of Bricks Study

Test on Bricks

About Bricks test20 Bricks are taken as a sample

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

Type	area affected
Nill Effloresence	Very Low
Slight	0-10%
Moderate	10-50%
Heavy	>50%
Serious	>50% + deposit are present in powder forms Heavy Flakes

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

Quick Revision of Bricks Study>

Defects in Bricks

**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

**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)

(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 23 117

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.