Civil engineering - Building Material - Timber

 Timber

Building material  Civil Engineering

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Timber

•         It is wood prepared for use in building and carpentry and other construction works as a building material

Wood 

•         Wood is a hard and fibrous natural substance which forms a major part of the the trunk and branches of a tree.

Dry Rot 

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Types of timber

• Timber is used for Engineering Activities and is obtained from trees that are generally two types.

1. Exogenous

•         Conifer Trees or Soft wood tree
•         Deciduous Trees or Hard wood tree

2. Endogenous

Exogenous Timber

Soft Wood or Conifer tree	Hard Wood or Deciduous Tree
1. Deodar, ChirPine ,spruce,fir,kail and larch. 2. Posses distinct Annular ring and Indistinct Medullary rays. 3. These tree have pointed Needle like leaves. 4. light in weight,colour.	1. Sal, Shishum, Oak,Teak. Babul. 2. Thes tree have flat Broad leaves 3.They shed their leaves in autumn and which grow back again in spring. 4. Posses indistinct annular rings and distinct medullary rays

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Endogenous Timber

Type	Description
Example	Bamboo Cane Palm PCB
Standing Timber	Timber containing a Living Tree.
Rough Timber	Timber which is obtain after falling of tree.
Log Timber	It is trunk of tree felt after cutting leaf of all branches of tree.
Converted Timber	Timber which is cut into commercial tree.

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About Timbers

No	Property	Soft wood	Hard wood
1.	Color	Lighter	Darker
2.	Growth	Faster	Slower
3.	Density	Low	High
4.	Weight	Less	More
5.	Annular Ring	Distinct	Indistinct

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With respect to fire resistance, timber is classified as refractory timber and non-refractory timber.

1. The non-refractory timber

•  it is resinous and it catches fire easily.  Examples of non-refractory timbers are chir, deodar, fir, etc.

2. The refractory timber

•  it is non-resinous and does not catch fire easily. Examples of refractory timbers are sal, teak, etc.

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Classification of Timber on the basis of Durability

Durability	Description  on basis of its average life
1 High         2. Moderate 3.Low	More than 10 years 5 to 10 years less than 5 years

Annular Ring

 These are also called Growth Ring

These are the concentric (same center) layer of wood.

 these are helpful in finding the age of tree

Properties of Timber

Sn	property	description
1.	Specific Gravity	generally SG. of wood is 1.54 IS code tells that wt of timber should be measured at 12% water content.
2.	Strength	The modular ratio of Elasticity of timber is  .5 to 1 × 10^4 Compressive strength of timber is maximum when load is applied parallel to grain On Application of external stress on time It behaves like as elastic material
3.	Moisture content	Timber by nature is hygroscopic, Anisotropic  And Orthographic ( hetrogenous) Recommended moisture content for structural  element is  12 to 20% for door 10 to 16% for windows not be more than 15 % for frame work If a dry piece is kept in a Saturated atmosphere it can absorb 15% of the weight.
4.	Shrinkage	Shrinkage of  timber is about 0.1% along the length. 3-5% along the  radius. 10-15% along the circumference.

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Defects in Timber

1. Defect due to seasoning of Timber

• Bow defect.
• Cup defect.
• End spring.
• Twist defect.

2. Defects due to Conversion

• Chip mark - Rough surface
• Diagonal Grain
• Chip mark,
• Torn grain,
• wane

• (i) Chip mark:These are the marks or signs placed by chips on finished surface of timber.
• (ii) Wane:It is the presence of original rounded surface on the manufactured timber.
• (iii) Diagonal grain: Improper sawing, Indicated by diagonal mark or straight grained surface of timber.
• (iv) Torn grain: It is the small depression on the finished surface due to falling of tool

3. Defect due to Fungi

Fungi attack the timber only when Following two condition are satisfied together:-

• a. Moisture content of timber is above 20%
• b. Presence of air for the growth of fungi.   

Note:- A wood submerged in water will not be attack by fungi because of absence of air.

Following are the defects caused by fungi on the timber

• Dry Rot,
•  wet rot,
•  sap stain, 
• blue stain,
•  Heart Rot,
•  Brown Rot, 
• White Rot, 

Dry Rot

• It is type of defect on timber due to 
  Fungi of some special type feed timber and during feeding they convert the timber into dry powder form.

• It take place due to improper ventilation,
•  no circulation of air ,presence of dampness on place
• It can be prevented by the proper seasoning of timber

  

following two condition is responsible for dry rot

• 1. greater than 20% moisture on timber
• 2. Presence of air for fungi growth

Note:- A wood submerged in water will not be attack by fungi because of absence of air.

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Wet Rot

• Some special type of fungi convert the timber into grayish brown powder
• Wet rot is caused by moisture being absorbed into the timber and make it soft and weak.

4. Defects due to Natural Forces

• a. Knots.
• b. Rind gall
• c. Shakes - heart shakes, star shakes, radial shakes, cup shakes.
• d.Cup shakes

shakes is the Longitudinal separation between annular ring

Heart shakes 

• 1 It starts from pith and move toward the sap wood
• 2 it is wider at pith and diminish towards outward
• 3 it is opposite to star shakes

Star shakes

• Cracks are wider at the circumference and diminish toward the pith or center of tree
• 
  

 5. Defects due to Insect

Is code related to Timber

• IS: 1141-1958- Classification of timber for seasoning purposes

• IS: 399-1963- Classification of commercial timbers and their zonal distribution

• IS: 1708-1969-Methods of testing of small specimen of timber

• IS: 4970-1973-Key for Identification of commercial timbers

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Timber board

• Block board: Block board consists of smaller timber block up to 25 mm in width. These blocks are cemented edge to edge and on each face plies up to 3 mm thickness are glued. Block board is extensively used for construction of railway carriages, bus bodies, marine and river crafts and for furniture making, partitions, panelling, prefabricated houses, etc.

• Batten board: The batten board is a board having a core made up of strips of wood usually 80 mm wide, each laid separately or glued or otherwise joined to form a slat which is glued between two or more outer veneers with the direction of the grain of the core running at right angles to that of the adjacent outer veneers. These are used for door panels, table tops etc.

• Fibre board are used for internal finish, wall panelling, floor, flush doors, table tops. These are used for fire and sound insulation in large commercial buildings and cinema houses. Hard board imparts internal appearance and finish to the structure.

Processing of Timber

Timber processing from trees includes the following stages:

• 1. Felling of trees
• 2. Seasoning of timber
• 3. Conversion of timber
• 4. Preservation of timber

Felling of trees: 

• The trees are knocked down (or) cut down to the ground. This is known as falling of trees.

Preservation of timber

Preservation of timber is carried to achieve the following three objectives:

• 1. Increase the life of timber
• 2. Make the timber durable
• 3. Protect the timber structures from the attack of destroying agencies such as fungi insects.

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Seasoning and Preservation of Timber

Make timber Fire Resistance

• Sir Abel’s Process: The surface of the timber is first painted with a weak solution of sodium silicate. Thereafter slaked fat lime solution of followed by a concentrated solution of silicate of soda. This makes timber fire-resistant.

• The fire resistance of timber can be enhanced by phosphates of ammonia, a mixture of ammonium phosphates and ammonium sulphate, borax and boric acid, sodium arsenate etc.

Types of seasoning and Preservation

Seasoning of timber: 

The process of drying of timber is known as seasoning of timber.

Under controlled environment, as early as possible, moisture is extracted at uniform rate from all parts of timber during seasoning.Seasoning is done in two ways:

• 1. Natural seasoning
• 2. Artificial seasoning

Natural seasoning: In this method, the seasoning of timber is carried out by natural air and hence, it is sometimes referred as air seasoning.

Artificial seasoning: This seasoning can be done in various methods like boiling, kiln seasoning, chemical seasoning,water seasoning and electrical seasoning.

Water seasoning

• Water seasoning means a sap of wood section is removed by the weathering action of water after that it is subjected to natural drying. This results in the reduction of twist and warping

Electrical seasoning

• Electrical seasoning uses high-frequency current which produces heat to dry out the timber. It is very fast method of seasoning. The only disadvantage is that it may cause the splitting of timber from the ends.

ASCU treatment 

• ASCU treatment is a method of preservation of timber, which results in the high durability of wood.
• In this method, one part of Arsenic penta-oxide, 3 parts of Copper Sulphate, and 4 parts of Potassium di-chromate are mixed and applied over timber which increases its resistance against white ants and hence, durability increases.
• This treatment increases resistance against attacks of white ants.

Creosote Oil:

• Produced by distillation of tar wood or coal
• Creosote is obtained from distillation of tar. For creosoting the timber is dried and then creosote oil is pumped under high pressure (1N/mm2) and high temperature. 
• It is one of the best antiseptic against fungi and other agents.
• I almost doubles the life of timber.
• Process is known as creosotic.
• Oil temperature of 50 degree cetigrade.
• Applied Pressure 0.7 to 1 N/mm2 uniformly over the timber

 

Sir Abel’s Process: 

• The surface of the timber is first painted with a weak solution of sodium silicate. Thereafter slaked fat lime solution of followed by a concentrated solution of silicate of soda. This makes timber fire-resistant.

Chemical Salts:

• Copper sulphate, Zinc Chloride, Mercury Chloride, Sodium Fluoride increase the durability of Structure.

Preservation with Coal Tar

• Hot tar is applied over the surface.
• It increase resistance against fire.

Oil paints or Solignum Paints:

• It increases the resistance to water.

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Some Important wood

• Mulberry wood is brown in colour and is so famous because of its elastic nature. It is strong, tough and elastic also. It can be easily turned and carved. It is used for making sports goods like cricket bats, hockey sticks etc.

• Mahogany is reddish Brown in colour and is durable in under-water conditions. It is used in furniture, fancy goods, ornamental panelling etc.

• Sal wood is hard, brown and close grained. It is fibrous and good polishing is difficult to achieve but it is good against moist conditions. It is used in railway sleepers, Wagons, Bridges etc.

• Deodar tree produces soft timber which is used for several purposes. It is used in cheap furniture, railway carriages, packing boxes etc.

Depending upon the ease with which Indian timbers can be seasoned, they are divided into three groups, namely, non- refractory timbers, moderately refractory timbers and highly refractory timbers. 

• 1. Non-refractory timbers can be rapidly seasoned without any trouble. They can be seasoned even in the open air and sun. Examples are deodar, simul, etc. 

• 2. Moderately refractory timbers have tendency to split and to crack during seasoning. They are therefore to be protected against rapid drying conditions. Examples are mango, rosewood, sissoo, teak, etc

• 3. Highly refractory timbers are likely to be damaged severaly during seasoning. They are difficult to season. Examples are axle wood, hopes, laurel, sal, etc. 

Note:

• The cost of seasoning of timber will naturally depend on the thickness of timber and type of timber with respect to seasoning. It will be more for highly refractory timbers and less for non- refractory timbers.

The timber shows high strength in the direction parallel to grains.

• Compressive strength along grain > Compressive strength across grain
• Tensile strength along grain > Tensile strength across grain
• Note:
• Tensile strength along grain is 2 to 4 times Compressive strength along grain.

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The various methods of sawing timber are as follows:

1. Ordinary sawn or flat sawn:

• Parallel cuts made throughout the length of the log, cutting parallel slices of planks, etc.
• Easiest and economical method
• Shrinkage of sapwood more than the heartwood
• Causing warp and twisting of planks

2. Quarter sawing

• Tendency to cup i.e. to curve in a transverse direction.
• When applied to wood, not having distinct medullar rays.
• This method produces very fine wood.

3. Rift or radial sawing

• Timber cut parallel to medullar rays and perpendicular to annual rings.

4. Tangential sawing

• Boards or planks sawn tangentially to annual rings. It is not suitable for flooring
• The different types sawing is as depicted below:

Strength of Timber

Wood has three principal axes namely longitudinal, tangential and radial axes. Since it is orthogonal material m it has three values of modulus of elasticity varying by as much as 150 to 1, three shear moduli varying from 20 to 1, and six Poisson’s ratios varying by 40 to 1.

For different strength:

a) Compressive strength:

•  The compressive strength is found to be highest when acting parallel to the axis of the growth. However compressive strength perpendicular to fibres of wood is much lower than that parallel to fibres of wood. Compressive strength parallel to fibre varies from 30.0 to 77.5 N/cm2.

b) Tensile strength: 

• Tensile strength along direction parallel to the grain is found to have greatest strength that can be developed under any other kind of stress. Tensile strength parallel to fibres is of the order 80.0 to 190.0 N/cm2.

c) Shearing strength: 

• Resistance to shear in across direction is found 3 to 4 times greater than that along fibres. The shear strength along fibre is found of the order 6.5 to 14.5 N/mm2.

• ∴ The strength of timber is highest in the direction of an angle of 0° to the grains.

Defect on timber

Checks:

•  These are also called as cracks which occur on timber.

Shakes:

•  Shakes are nothing but cracks which separates the wood fibres partly or completely. There is a longitudinal separation in the wood between the annual rings.

Knots:

•  These are bases of branches or limbs which are cut-off from tree. 
• The portion from which branch is removed receives nourishment from the stem for the long time and ultimately results in the formation of dark hard rings which are known as knots.

Rind galls:

•  Overgrowth of Timber in some parts of a tree may result in some typical defects. 
• Rind gall are quite common. A rind gall is simply a highly thickened, enlarged wood cover developed over an injured part of the tree. 
• The meaning of rind is bark and gall is abnormal growth.
•  So abnormal growth of the bark of the trees is called Rind galls. Improper cutting of branches causes this abnormal growth

Shakes

• Shakes are defects that occur around the annual ring or growth ring of timber.

Warehouse

• A warehouse is a large building where raw materials or manufactured goods are stored until they are exported to other stores, sites.

Characteristics of warehouse are as follows :

• Building should have minimum number of windows.
• Building should be leak proof as well as moisture proof.
• Roof should be waterproof.

Wood Products

1. Veneer

• Veneering is the process of manufacture of wood based products in which thin sheets of woods are produced which are known as veneers.
• The thickness of  veneers varies from 0.4 to 0.6mm
• In no case it should be exceed 1mm
• Walnut is most preferable wood

2. Plywood

• A wood panel glued under pressure from an odd number usually 3 to 13 of layers/piles of veneers is known as Plywood.
• Used for Partition, ceilings, doors, concrete form work, plywood board, making furniture top sheet.

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Civil engineering - Building Materials - mortar and Lime

 Mortar and lime

Building material Civil engineering

Mortar

Mortar is defined as the mixture containing a binding agent Like lime or cement,water and fine aggregate.

On the basis of Binding agent mortar is classified into following types

1 lime mortar

It does not set quickly

Lime mortar generally made with hydraulic Lime

Its provide better resistance against rain penetration 

It is unliable to crack when compared with cement mortar

2.Cement Mortar

It is most suitable for construction work in Water Logged area

Gives shrinkage crack

3.Gauge Mortar

It is also called as composite mortar or cement lime mortar

with proportion of 1:1:6 to 1:1:8

After addition of cement It should be used with 1 to 2 hr

4 Light weight Mortar

It is Prepared by adding the material 

like as Wood - Powder , saw-dust, etc to lime/cement mortar

5. Surkhi Mortar

Surkhi is a pozzolanic material and it is very fine in size 

and it must be pass from a 4.75 mm sieve

surkhi is added to lime mortar to give hydraulically ability to set in presence of water

Lime-Cement Mortar:

Also known as Gauged mortar.

It is made from cement and lime.

The advantages of lime-cement mortar are 

increased Water retentivity, 

workability,

 bonding properties 

and frost resistance.

This mortar gives good and smooth plaster finish and is used in buildings.

Selection of Mortar

Selection of Mortar

No	work	Proportion cement:sand
1.	Normal Brick work	1:6
2.	Plaster work	1:3 to 1:4 1:2 (lime:mortar)
3.	Pointing in m2	1:1 to 1:2
4.	Damp Proof Work	1:2
5.	Grouting	1:1.5
6.	Guniting	1:3

Note - Addition of 5% to 6% of moisture content by weight increase

the volume of dry sand from 13% to 18%

Lime

CaCO3 = CaO + CO2 

CaO + H2O = Ca(OH)2

Chart for lime reactions

no	Name	Chemical formula
1.	Limestone	CaCO3
2.	Quick lime or Lump lime	CaO
3.	Ca(OH)2	Hydrated lime or slaked lime
4.	H2o	water

When the water is added to quick lime in sufficient quantity then a Chemical

reaction take place due to which quicklime Swell, Crack and Finally we get

Hydrated lime

Types of lime

No	Type	Description
1.	Fat lime	Also known as  Pure lime, Rich lime,  White lime etc. It contains impurity less than 5% hence  It has High Calcium Oxide content It is obtained from Sea shell, Coral Reefs etc It can be used in white washing and Plastering.
2.	Hydraulic Lime	This is called water lime because it can set under water. It contain Silica, Alumina and Iron Oxide in small quantity. It can be suitable for making mortar and using in masonry construction
3.	Poor lime	It is also called Impure lime or Weak lime, lean lime It contains 30% Impurities as compared to pure Lime
4.	Milk of Lime	A thin pour able suspension of slake lime in water is called milk of lime.
5.	Note	slaked lime is utilized in painting and decorative work Hydraulic lime is obtained from Kankar Non hydraulic lime from calcined dolomite stones. Burning of limestone in presence of Oxygen is known as Calcination.

Bulking of Sand

• The increase in moisture of sand increases the volume of sand and is known as bulking of sand.
• The volume of dry sand increases due to absorption of moisture. These volume increase of dry sand is known as bulking of sand. When dry sand comes in contact with moisture, a thin film is formed around the particles, which causes them to get apart from each other. This results in increasing the volume of sand. Addition of 5% and 6% of moisture content by weight increases the volume of dry sand from 18% to 38%.

Reason for the bulking of sand

• The reason is that moisture causes the film of water around sand particles which results in the increase of the volume of sand
• Bulking structure in sand is due to capillary action.
• For a moisture content percentage of 5 to 8, there will be an increase in volume up to 20 to 40 percent depending upon the sand
• If the sand is finer there will be more increase in volume

Graphical representation of bulking of sand is shown below:

Terracotta

• It is refractory clay brick and used in ornamental parts of buildings.
• The clay used for its manufacture should be of superior quality 
• and should have sufficient iron and alkaline matters. 
• It is burnt in special furnace known as Muffle furnace.

Water needed for complete Hydration of Cement

Approximately 23% water by weight is required for hydration and 15% water is entrapped in between the voids of cement. So, the total water required for complete hydration and workability is 38% by weight.

Segregation

• As per clause 13.2 of IS 456: 2000, the maximum permissible free fall of concrete to avoid segregation may be taken as 1.5 m or 150 cm.

• Segregation can be defined as the separation of the constituent materials of concrete.

• Insufficiently mixed concrete with excess water content shows a higher tendency for segregation.

• Dropping of concrete from heights as in the case of placing concrete in column concreting will result in segregation.

Slump and compaction Factor

Consistency	Slump	Compaction Factor
Moist earth	0	0.65-0.7
Very Dry	0-25	0.7-0.8
Dry	25-50	0.8-0.85
Plastic	50-100	0.85-.95
Semi-fluid	100-175	0.95-1

Plastic asphalt 

• It is a mixture of cement and asphalt. Mechanical properties, resilient modulus, temperature susceptibility, water damage, creep and permanent deformation resistance are all improved by the mixing of cement and asphalt altogether.

• It is used for filling patches and cracks of flexible pavements. The temperature sensitiveness of the asphalt is overcome by the application of cement to it. Thus, it is primarily used for repair or reconstruction purpose.

Types of lime:

1. Fat lime: 

It slacks rapidly and its volume is increased by 2 to 2.5 times of its original volume hence, it is referred as fat lime. It is also known as pure lime, rich lime, high calcium lime. It has more than 95% purity.

Properties- Slow setting, High plasticity, Soluble in water, Vigorous slaking, Perfectly white colour

Application- White wash & Plastering

Source- Sea shells

2. Hydraulic lime: 

It is also known as water lime as it is capable of setting in water and damp condition. It has 70% to 90% purity.

Properties- Insoluble in water, Low plasticity, Less slaking, Off white colour, High hydraulicity

Application- Brick masonry or Stone masonry

Source- burning of Kankar

3. Poor lime: 

It is also known as Impure or lean lime. It has less than 70% purity.

Properties- Muddy Colour

Application- Used in brick work around foundation

Floats are used to press mortar and spread it uniformly.

A trowel is a small hand tool used for digging, applying, smoothing, or moving small amounts of viscous or particulate material. Aluminium rod is used to strike off excess mortar.

A brush is used to clean the mortar. Floats are used to press mortar and spread it uniformly.

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Quick Revision of Bricks: Civil engineering study vk

 Quick Revision of Bricks

Building material Civil engineering vk

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

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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

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About Bricks

No.	1.	2.
No of bricks	500	on one  cubic meter
Purpose of Frog providing	to help	bonding between brick and mortar
weight of one brick	in kg	3 to 3.5 kg
unit weight of one brick	in kg/cu m	19 KN/m3

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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	(2-5%) or <10%	prevent shrinkage on drying	melt and brick loose  its shape
Iron Oxide	3-5% or <7%	gives red color, helps lime to fuse with sand	dark blue or black color if greater than 5 %
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

Classification of Bricks

properties	class 1st  or Good Bricks or Grade A	class 2nd  or Grade B	class 3rd  common brick or Grade C
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 AA Grade bricks shall have minimum compressive strength 14 N/mm2 or 140 kg/cm2

Manufacturing process of Brick

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   -  -  -

Manufacturing process of Brick
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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 sunrays.
Burning	900 - 1200°C Bricks should be properly burnt Temperature 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	1. burning can be done by two ways  clamp burning and kiln burning 2. Pugmill is used for making bricks generally for large scale. and in pugmill the soil is prepare for making upto15000 bricks per day.

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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

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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
		3 lac bricks are made in every time. It has 10 to 20 chambers. Generally 12 is suitable. In this kiln generally 900°C temp is used.
Note	both methods are using kiln burning

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Test on Bricks

About Bricks test

20 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 Generally 20 bricks are taken out of 20000 bricks for dimension test.	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

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                                                            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 or Refractory Bricks

These type of bricks are made from fire clay.

In these types of brick generally the amount of sillica is increased and lime is decreased.

In this type of brick earth generally the amount of lime and iron oxide is much less like 2 to 3%

This bricks is made on 1600 to 1700 degree celcius.

Water absorbtion is 5 to 10 % of dry wt of 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 mm)
• 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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