building materials and constructions (1)

8/7/2019 Building materials and Constructions (1)

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Building materials andBuilding materials andConstructionsConstructions

UnitUnit--11Building StonesBuilding Stones--Classification and quarryingClassification and quarrying

PropertiesProperties--structural requirementsstructural requirements--dressing.dressing.BricksBricks--Composition of Brick earthComposition of Brick earth--

Manufacture and structural requirementsManufacture and structural requirements


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IntroductionIntroduction Building material is anyBuilding material is any materialmaterial which is used for awhich is used for a

constructionconstruction purpose.purpose.

Natural materialsNatural materials

2 Fabric2 Fabric

3 Mud and clay3 Mud and clay

4 Rock4 Rock

5 Thatch5 Thatch 6 Brush6 Brush

7 Ice7 Ice

8 Wood8 Wood

9 Concrete9 Concrete

10 Metal10 Metal

11 Glass11 Glass 12 Plastic12 Plastic

13 Foam13 Foam

14 Cement composites14 Cement composites


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STONESSTONES

Mud, stone, and Brick are the most basicMud, stone, and Brick are the most basicbuilding materials.building materials.

The stone is always obtained from rock.The stone is always obtained from rock.The rock quarried from quarries is calledThe rock quarried from quarries is calledstone.stone.

Quarried stone may be in the form ofQuarried stone may be in the form ofstone blocks, stone aggregate, stonestone blocks, stone aggregate, stoneslabs, stone lintels etc.slabs, stone lintels etc.


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uses of stoneuses of stone

For masonry workFor masonry work

For lintels and vertical columnsFor lintels and vertical columns For covering floors and buildingsFor covering floors and buildings

For paving of roads and footpathsFor paving of roads and footpaths

As an aggregate in cement as well as limeAs an aggregate in cement as well as limeconcretes.concretes.


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Properties Of StonesProperties Of Stones

Strength & Durability:Strength & Durability:

The more compact grained and heavier aThe more compact grained and heavier astone the harder it is. Due to alternatestone the harder it is. Due to alternatewetting and drying the resulting crushingwetting and drying the resulting crushingstrength can be reduced even up to 30strength can be reduced even up to 30--

40%. Being dry stones allow more40%. Being dry stones allow morecrushing strength than when wet.crushing strength than when wet.


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SUNLIGHT:SUNLIGHT:

When some stones are used in exterior applications and exposed toWhen some stones are used in exterior applications and exposed todirectdirect sunlight they fade or change colorsunlight they fade or change color.. Dark colored stones andDark colored stones andthose that contain organic matter (those that contain organic matter (matter that has come from a oncematter that has come from a once--

living organismliving organism ) will generally fade to a much lighter color. The Coral) will generally fade to a much lighter color. The Coralstone being of a biogenic origin contains organic material thatstone being of a biogenic origin contains organic material that willwillbe affected by ultraviolet exposure.be affected by ultraviolet exposure.

MOISTURE:MOISTURE:

Some stones have moisture sensitive mineral contents that willSome stones have moisture sensitive mineral contents that willcause the stone to develop rust spots, or other color variations, orcause the stone to develop rust spots, or other color variations, orcontain moisture sensitive substances that will cause blotchy andcontain moisture sensitive substances that will cause blotchy andstreaking discolorations. Certain lime stones contain bituminousstreaking discolorations. Certain lime stones contain bituminousmaterials that are soluble when exposed to moisture. Some marblesmaterials that are soluble when exposed to moisture. Some marblesare also moisture sensitive when in high moisture areas, showersare also moisture sensitive when in high moisture areas, showersandand those with steam features; these stones have a tendency tothose with steam features; these stones have a tendency todevelop dark botches.develop dark botches.


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Porosity & Permeability:Porosity & Permeability:

PorosityPorosity is the ratio of pores (microis the ratio of pores (micro--voids) in the stone, to its total solidvoids) in the stone, to its total solid

volume. Pores and the capillary structure develop differently in each of thevolume. Pores and the capillary structure develop differently in each of thethree stone groups. Dense and compact stones have very few or no pores inthree stone groups. Dense and compact stones have very few or no pores inthem. An important feature of sedimentary rocks is their porosity. Pores arethem. An important feature of sedimentary rocks is their porosity. Pores arenatural holes in the stones which allow fluids like rainwater to enter and leavenatural holes in the stones which allow fluids like rainwater to enter and leavethe fabric. Some free fluid flow through a rock is necessary to maintain thethe fabric. Some free fluid flow through a rock is necessary to maintain therock's durability, and it is not always advisable to block such flow by usingrock's durability, and it is not always advisable to block such flow by usingincorrect mortar mixes or by injecting unsuitable synthetic fluids.incorrect mortar mixes or by injecting unsuitable synthetic fluids.

Very high porosities, however, may allow excessive volumes of corrosiveVery high porosities, however, may allow excessive volumes of corrosivefluids such as acid rainwater to enter and cause severe damage to the rock.fluids such as acid rainwater to enter and cause severe damage to the rock.

Thin section rock analysis can identify where such problems are likely toThin section rock analysis can identify where such problems are likely tooccur. Most durable sedimentary building stones commonly have moderateoccur. Most durable sedimentary building stones commonly have moderateporosity.porosity.

Associated with stones porosity is its permeability. This is the extent to whichAssociated with stones porosity is its permeability. This is the extent to whichthe pores and capillary structures are interconnected throughout the stone.the pores and capillary structures are interconnected throughout the stone.These networks, their size, structure and orientation affect the degree andThese networks, their size, structure and orientation affect the degree anddepth to which moisture, vapors and liquids can be absorb into the interior ofdepth to which moisture, vapors and liquids can be absorb into the interior ofthe stone or migrate from the substrate by capillary action through the stone.the stone or migrate from the substrate by capillary action through the stone.

Permeability is increased when a stone is highly fractured or the veiningPermeability is increased when a stone is highly fractured or the veiningmaterial is soft or grainy. A particular variety of stone may be highlymaterial is soft or grainy. A particular variety of stone may be highly

permeable (a well defined interconnected network of pores), although itspermeable (a well defined interconnected network of pores), although itsporosity is low (a low percentage of voids).porosity is low (a low percentage of voids).

TThe size and shapes of pores and the capillary structure differs in stones andhe size and shapes of pores and the capillary structure differs in stones andis an important factor in relation to stone decay.is an important factor in relation to stone decay.


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Color, Surface Texture andColor, Surface Texture andVeining:Veining:

Hardness & weathering:Hardness & weathering:

HardnessHardness is the property of a material to avoid and resist scratching. It isis the property of a material to avoid and resist scratching. It isdetermined by comparison with the standard minerals of the Mohs scale. Thedetermined by comparison with the standard minerals of the Mohs scale. Theobjective of the MOH Scale is to measure stones resistance to hardness.objective of the MOH Scale is to measure stones resistance to hardness.

Measurement ofHardness:Measurement ofHardness: TalcTalc

GypsumGypsum

Calcite (Most Marbles)Calcite (Most Marbles)

FluoriteFluorite

ApatiteApatite

Feldspar (Granite)Feldspar (Granite)

Quartz (Granite)Quartz (Granite)

TopazTopaz CorundumCorundum

DiamondDiamond

WeatheringWeathering


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WeatheringWeathering

ItIt is a complex interaction of physical, chemical andis a complex interaction of physical, chemical andbiological processes that alters the stone in some general orbiological processes that alters the stone in some general orspecific way. The physical properties of stone differs widelyspecific way. The physical properties of stone differs widelybetween stone groups and even within the same stone type.between stone groups and even within the same stone type.

The mineral composition, textural differences, varyingThe mineral composition, textural differences, varyingdegrees of hardness and pore/capillary structure are thedegrees of hardness and pore/capillary structure are themain reasons why stone nor all the surface of the samemain reasons why stone nor all the surface of the samestone shows signs of alteration the same and evenly. Thesestone shows signs of alteration the same and evenly. Theseminerals can be broken down, dissolved or converted to newminerals can be broken down, dissolved or converted to newminerals by a variety of processes which are grouped asminerals by a variety of processes which are grouped asMechanical and Chemical. Intensity and duration are two keyMechanical and Chemical. Intensity and duration are two keyelements that govern to what extent weathering reactionselements that govern to what extent weathering reactions

will have on stone.will have on stone.


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How are rocks classifiedHow are rocks classified

The rocks may be classified in theThe rocks may be classified in thefollowing 4 ways.following 4 ways.

i.Geological classificationi.Geological classification

ii. Physical classificationii. Physical classification

iii. Chemical classificationiii. Chemical classification


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Geological classification ofGeological classification ofstonesstones


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Geological classification of stonesGeological classification of stones

Geological classification of stonesGeological classification of stones Geologically the stones can be classified as follows:Geologically the stones can be classified as follows: 1) Sedimentary stones:1) Sedimentary stones: (a)Characteristics:(a)Characteristics:

Sandstone, limestone, dolomite originally formed mainly in sea water, or lakes, fromSandstone, limestone, dolomite originally formed mainly in sea water, or lakes, fromthe remains of animals and plants, also from transportation and deposition of rockthe remains of animals and plants, also from transportation and deposition of rockproducts.products.

A. Formed at or near the surfaceA. Formed at or near the surfaceB. Distinctive strataB. Distinctive strataC. Many fossils have been found in this type of rockC. Many fossils have been found in this type of rockGrain shapeGrain shapeA. RoundedA. Rounded

B. AngularB. Angular (b) Classification:(b) Classification: .A. Detrital is made from disintigrated pre.A. Detrital is made from disintigrated pre--existing rock.existing rock.

B. Biogenetic is made from shells and other fossilized fragments.B. Biogenetic is made from shells and other fossilized fragments.C. Chemical is made from chemical precipitation.C. Chemical is made from chemical precipitation.


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examples of sedimentary rocks.examples of sedimentary rocks.

Sand stoneSand stone

limestonelimestone

LigniteLignite

slate andslate and

shaleshale


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3)Igneous stones:3)Igneous stones: These stones are formed when the magma from the earth cools inside the earth or on the earth surface.These stones are formed when the magma from the earth cools inside the earth or on the earth surface. (a) Characteristics:(a) Characteristics:

AA.. IntrusiveIntrusive -- subsurface crystallizationsubsurface crystallizationB. ExtrusiveB. Extrusive-- above surface crystallizationabove surface crystallization*note Temperature and time has alot of effect on crystal sizes i.e.: Heat + time = Larger crystal*note Temperature and time has alot of effect on crystal sizes i.e.: Heat + time = Larger crystalIgneous form occurrence below ground presents itself in 2 basic ways:Igneous form occurrence below ground presents itself in 2 basic ways:I

ntrusive basic dike, which is like having layers of cardboard over your head and punching your fist up into it.I

ntrusive basic dike, which is like having layers of cardboard over your head and punching your fist up into it.Plutonic, this is like a huge hot ball of stone burning its way around deep below the surface and it usually hasPlutonic, this is like a huge hot ball of stone burning its way around deep below the surface and it usually has"hot arms" that reach out from its main mass. Crystal habit can successfully delineate a Igneous stones origin,"hot arms" that reach out from its main mass. Crystal habit can successfully delineate a Igneous stones origin,usually. Dikes are cooler thus forming smaller crystals and Plutons are hotter thus forming larger crystals.usually. Dikes are cooler thus forming smaller crystals and Plutons are hotter thus forming larger crystals.C. MineralcontentC. MineralcontentD. GrainsizeD. Grainsize, Plutonic >3/16" coarse. Extrusive 1/64", Plutonic >3/16" coarse. Extrusive 1/64" -- 3/16" Medium and < 1/64" fine3/16" Medium and < 1/64" fineE. CrystalshapeE. CrystalshapeF. TextureF. Texture % A, %B, crystal angle.% A, %B, crystal angle.G. ColorG. Color

(c) Classification:(c) Classification: A. Acid rocks > 65% Si + > 10% Modal QuartzA. Acid rocks > 65% Si + > 10% Modal Quartz

B.I

ntermediate rocks 55%B.I

ntermediate rocks 55% -- 65% Si65% SiC. Basic rocks 45%C. Basic rocks 45% -- 55% Si < 10% Modal Quartz55% Si < 10% Modal QuartzD. UltraD. Ultra--Basic < 45% Si.Basic < 45% Si.

Related PagRelated Pag


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2) Metamorphicstones:2) Metamorphicstones: (a) Characteristics:(a) Characteristics: Marble, serpentine, onyx, slate, quartzite, gneiss are produced from sedimentary or igneous rocks by the action ofMarble, serpentine, onyx, slate, quartzite, gneiss are produced from sedimentary or igneous rocks by the action of

heat and pressure.heat and pressure.A. No pressureA. No pressure -- fossils survivefossils surviveB. Low pressureB. Low pressure -- fossils distorted or destroyedfossils distorted or destroyedC. Moderate pressureC. Moderate pressure -- Grains form moderatelyGrains form moderatelyD. High pressureD. High pressure -- Active fluids may circulateActive fluids may circulateE. Heat alone, Metamorphic Aureole surrounding a deep plutonic intrusions, possibly with active fluidsE. Heat alone, Metamorphic Aureole surrounding a deep plutonic intrusions, possibly with active fluidsF. Dynamic MetaF. Dynamic Meta -- Large scale movement phenomenaLarge scale movement phenomenaG. Crushing actions produce Xylonite Meta rock from powderG. Crushing actions produce Xylonite Meta rock from powderH. Low angle thrust fault: Plate pressure coupled with subsidenceH. Low angle thrust fault: Plate pressure coupled with subsidenceI. Thrust movement, plate movementI. Thrust movement, plate movement

(b) Classification:(b) Classification:

1. Structure1. StructureA. Contact type is crystallineA. Contact type is crystallineB. Regional type is usually foliatedB. Regional type is usually foliated

2. Grain size2. Grain sizeA. +0 Big grain, High pressureA. +0 Big grain, High pressureB. 00 Med grain, Med pressureB. 00 Med grain, Med pressureC.C. --o Small grain, Low pressureo Small grain, Low pressure

3. Basic PSI and temperature:3. Basic PSI and temperature: Basic PSI and temperature of occurrence is 480* FBasic PSI and temperature of occurrence is 480* F -- 1472* F 2,0001472* F 2,000 -- 10,000 K10,000 K


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examples of metamorphic rocks.examples of metamorphic rocks.

MarbleMarble

LateriteLaterite

GneissGneiss


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igneous rocks classifiedigneous rocks classified

Volcanic igneous rocksVolcanic igneous rocks

eg. Basalteg. Basalt

HypaHypa--bysal rocksbysal rocks

eg. Doleriteeg. Dolerite

Plutonic rocksPlutonic rockseg. Graniteeg. Granite


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physical classification of rocksphysical classification of rocks

I. Stratified rocksI. Stratified rocks

ii. Unstratified rocksii. Unstratified rocks

:compact granular in nature:compact granular in nature PEGMATITEPEGMATITE

iii. Foliated or laminated rocks:iii. Foliated or laminated rocks: Splits up in one directionSplits up in one direction--MicaMica


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Chemical classification of rocksChemical classification of rocks i.Silicious rocksi.Silicious rocks ((Silica predominatesSilica predominates))Ex:Ex:-- Granite, quartzite, trap, basalt, sand stone:Granite, quartzite, trap, basalt, sand stone:

ii. Argillaceous rocks (ii. Argillaceous rocks (Clay predominatesClay predominates))

Ex:Ex:--Laterite, slateLaterite, slate


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Chemical classification of rocksChemical classification of rocks

iii. Calcareous rocks (iii. Calcareous rocks (Calcium Carbonate predominatesCalcium Carbonate predominates))

Ex:Ex:---- Limestone, marble, dolomite, kankarLimestone, marble, dolomite, kankar

Limeston

e (Jersey)vinylflooring

housetohome.co.uk


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Stone QuarryingStone Quarrying

Process of Taking out stones from naturalProcess of Taking out stones from naturalrock beds is known as quarr(exposedrock beds is known as quarr(exposed

surface of natural rocks)ying.surface of natural rocks)ying.

Difference between quarrying and miningDifference between quarrying and miningis that operations are carried out atis that operations are carried out at

ground level in an exposed condition.ground level in an exposed condition.


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Stone QuarryingStone Quarrying

Process of Taking out stones from natural rockProcess of Taking out stones from natural rockbeds is known as quarr(exposed surface ofbeds is known as quarr(exposed surface ofnatural rocks)ying.natural rocks)ying.

Difference between quarrying and mining is thatDifference between quarrying and mining is thatoperations are carried out at ground level in anoperations are carried out at ground level in anexposed condition.exposed condition.

Methods of Quarrying:Methods of Quarrying:

I. Quarrying with hand toolsI. Quarrying with hand toolsii.Quarrying with channeling machineii.Quarrying with channeling machineiii.Quarrying by blasting.iii.Quarrying by blasting.


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Quarrying with hand toolsQuarrying with hand tools

A) Digging or excavatingA) Digging or excavating

1.Hammer1.Hammer

2.Drills2.Drills 3.chisel3.chisel


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Quarrying with hand toolsQuarrying with hand tools

B) HeatingB) Heating

C) Wedging 4.Plug and featherC) Wedging 4.Plug and feather

5.wedges5.wedges


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Quarrying with channeling machineQuarrying with channeling machine


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Quarrying by blastingQuarrying by blasting


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Tools for BlastingTools for Blasting

1)Dipper:1)Dipper:

2)Jumper:2)Jumper:

3)Priming Needle:3)Priming Needle: 4)Scarping spoon:4)Scarping spoon:

5)Tamping bar:5)Tamping bar:


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Precautions in BlastingPrecautions in Blasting


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Materials for blasting:Materials for blasting:somesome

blasting materialsblasting materials 1. Detonators:1. Detonators:

2.Explosives:2.Explosives:

Gun powder, Dynamite, Gun cotton,Gun powder, Dynamite, Gun cotton,Cordite, Blasting gelatinCordite, Blasting gelatin

3.fuses3.fuses


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methods of quarrying stonesmethods of quarrying stones

1. Digging or excavating1. Digging or excavating

2. Heating2. Heating

3. Wedging3. Wedging

4. Blasting4. Blasting


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Dressing of stonesDressing of stones

Stones obtained from quarry are in irregularStones obtained from quarry are in irregularsizes and shapes and cannot be usedsizes and shapes and cannot be used

as such oin masonry work, without dressing.as such oin masonry work, without dressing.Dressing of stones is a process, carried out withDressing of stones is a process, carried out withthe help of hand tools, to give proper shape andthe help of hand tools, to give proper shape andsurface to the stone, before its use in masonrysurface to the stone, before its use in masonryor any other work.or any other work.


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Purpose of dressing of stonesPurpose of dressing of stones

To get the appearance of stone masonryTo get the appearance of stone masonry

To suit the requirements of stone masonryTo suit the requirements of stone masonry

To make the transportation of stone easyTo make the transportation of stone easyand economical from the quarry.and economical from the quarry.


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Dressing Of StonesDressing Of Stones


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FINISHESFINISHES

A POLISHEDA POLISHED SURFACE CREATES A BEAUTIFUL GLOSSY SHINE FROM THE NATURALSURFACE CREATES A BEAUTIFUL GLOSSY SHINE FROM THE NATURAL

REFLECTION OF THE STONE]S CRYSTALS. THE MIRRORREFLECTION OF THE STONE]S CRYSTALS. THE MIRROR--LIKE SHINE ISLIKE SHINE IS

ACCOMPLISHED BY USING PROGRESSIVELY FINER POLISHING HEADS DURINGACCOMPLISHED BY USING PROGRESSIVELY FINER POLISHING HEADS DURING

THE POLISHING PROCESS, SIMILAR TO THE WAY THAT SANDPAPER SMOOTHESTHE POLISHING PROCESS, SIMILAR TO THE WAY THAT SANDPAPER SMOOTHES

HARDWOOD FURNITUREHARDWOOD FURNITURE..

An acidAn acid--washed finishwashed finish is shiny withis shiny withsmall etching marks (pits in the surface).small etching marks (pits in the surface).This finish shows fewer scratches and isThis finish shows fewer scratches and is

much more rustic in appearance than amuch more rustic in appearance than ahoned finish.honed finish.


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A flamed finishA flamed finish is achieved by heatingis achieved by heatingthe surface of the stone to extremethe surface of the stone to extreme

temperatures, followed by rapid cooling.temperatures, followed by rapid cooling.


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Droved finish:Droved finish: finish known asfinish known as drovedroveworkwork is somewhat similar to tooled work,is somewhat similar to tooled work,

but is generally executed on harder stone.but is generally executed on harder stone.There are two general classes of droveThere are two general classes of drovework, namely,work, namely,hand drovehand drove andand machinemachinedrovedrove,,


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ssss


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Engineering MaterialEngineering Material

BrickBrick

CEE, KUKTEMCEE, KUKTEM

B i kB i k I t d tiI t d ti


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BricksBricks Introduction:Introduction:

Bricks will categorized with different used:Bricks will categorized with different used: load bearing wallload bearing wall

NonNon--Load bearing wallLoad bearing wall

Insulation wallInsulation wall

Covering wall.Covering wall. Selection of bricks based on their using.Selection of bricks based on their using.

Brick shape : 4 side geometric with lengthBrick shape : 4 side geometric with length

2 x from width. The thickness is 2/3 of2 x from width. The thickness is 2/3 ofwidthwidth

Standard size of bricks is 215 x 102.5 x 65Standard size of bricks is 215 x 102.5 x 65mm

40


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Composition of goodbrickearthComposition of goodbrickearth

AluminaAlumina

SilicaSilica

Lime:Lime:

Oxide ofIronOxide ofIron

MagnesiaMagnesia


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Manufacture Of bricksManufacture Of bricks

Preparation of clay:Preparation of clay:

Moulding:Moulding:

Drying:Drying:

Burning:Burning:

ClampsClamps

KilnsKilns


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Clamp burningClamp burning

use of brick clamps is by far the oldest anduse of brick clamps is by far the oldest andmost rudimentary method of firing bricks. Whenmost rudimentary method of firing bricks. When

"scoved" (that is, plastered on the outside for"scoved" (that is, plastered on the outside forgreater efficiency), they become scove clampsgreater efficiency), they become scove clampsor kilns. If the clamp is enclosed within fouror kilns. If the clamp is enclosed within fourpermanent walls, it becomes a rectangularpermanent walls, it becomes a rectangular

Scotch kiln, but in its most basic form it is aScotch kiln, but in its most basic form it is acarefully constructed stack or clamp of bricks.carefully constructed stack or clamp of bricks.


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Clamp BurningClamp Burning

Disadvantages of brick clampsDisadvantages of brick clamps Basic brick clamps are the least energy efficient method of firing bricks, with a lot of heat being lost by radiation throughBasic brick clamps are the least energy efficient method of firing bricks, with a lot of heat being lost by radiation through ththe walls, ande walls, and

convection from the top of the clamp. The fuel is not consumed efficiently as there is litt le or no control over its combusticonvection from the top of the clamp. The fuel is not consumed efficiently as there is litt le or no control over its combustionon once theonce theclamp is lit. Fuel consumption of 2,800 to 3,500 kJ/kg fired brick is to be expected, depending on the size and design of theclamp is lit. Fuel consumption of 2,800 to 3,500 kJ/kg fired brick is to be expected, depending on the size and design of the clclamp, plusamp, plusthe fuel and method of combustion. This low figure is partially due to the high percentage of broken and over or under firedthe fuel and method of combustion. This low figure is partially due to the high percentage of broken and over or under fired bribrickscksproduced.produced.

They are very labour intensive, being assembled and disassembled by hand, and if not built correctly and fired badly, can resThey are very labour intensive, being assembled and disassembled by hand, and if not built correctly and fired badly, can resultult in a veryin a veryhigh percentage of incompletely fired bricks. Up to 20% of the bricks produced by a basic brick clamp can normally be expectehigh percentage of incompletely fired bricks. Up to 20% of the bricks produced by a basic brick clamp can normally be expected td to beo beover or under fired by this method.over or under fired by this method.

They are very slow to fire, taking several days to heat up and cool down, and there is little or no control over the firing oThey are very slow to fire, taking several days to heat up and cool down, and there is little or no control over the firing oncence it hasit hasstarted.started.

They are highly susceptible to the prevailing weather conditions, especially strong winds, which will result in a very unevenThey are highly susceptible to the prevailing weather conditions, especially strong winds, which will result in a very uneven fifiring, withring, withmany more underfired and overfired bricks.many more underfired and overfired bricks.


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BULLS TRENCH KILNBULLS TRENCH KILN


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Working PrincipleWorking Principle


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Continuous KilnsContinuous Kilns


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Firing of Bricks:Firing of Bricks: Bricks are burnt either in a periodic kiln or aBricks are burnt either in a periodic kiln or a

continuous tunnel kilncontinuous tunnel kiln -- In a perio

dic kilnIn a perio

dic kiln bricks are loaded in afterbricks are loaded in afterinitial drying, fired, cooled, and unloaded; and the process is repeatedinitial drying, fired, cooled, and unloaded; and the process is repeatedafter a certain period (say a month)after a certain period (say a month) -- In a continuous tunnel kilnIn a continuous tunnel kilnthe bricks are loaded onto special railcars that pass continuously throughthe bricks are loaded onto special railcars that pass continuously throughvarious processes to emerge at the other end fully burnedvarious processes to emerge at the other end fully burned

Stages of burning:Stages of burning: WaterWater--smoking and dehydration (drives off thesmoking and dehydration (drives off the

remaining water from clay at 40remaining water from clay at 40oo to 150to 150oo C)C) -- Oxidation andOxidation andVitrification:Vitrification: Temperature of furnace rises to 1000Temperature of furnace rises to 1000oo to 1300to 1300oo CC -- ClayClaytransformed to a ceramic materialtransformed to a ceramic material -- FlashingFlashing:: Fire is regulated toFire is regulated tocreate a reducing atmosphere in the kiln that develops a color variation increate a reducing atmosphere in the kiln that develops a color variation in

the bricksthe bricks -- Cooling:Cooling: BricksBricks are cooled under controlled conditions toare cooled under controlled conditions toachieve the desired color and to avoid any thermal crackingachieve the desired color and to avoid any thermal cracking -- The entireThe entireprocess of firing takes from 40 to 150 hoursprocess of firing takes from 40 to 150 hours

Color of a brick:Color of a brick: Depends on the chemical composition of clay,Depends on the chemical composition of clay,temperature, and chemistry of firetemperature, and chemistry of fire -- Iron in clay turns to red in oxidizingIron in clay turns to red in oxidizingfire and to purple in reducing firefire and to purple in reducing fire -- Calcium oxides gives creamy/whiteCalcium oxides gives creamy/whitecolorcolor -- For bright colors, all faces of bricks can be glazed like potteryFor bright colors, all faces of bricks can be glazed like pottery

during normal firing or during subsequent firingduring normal firing or during subsequent firing

9.4 MANUFACTURE OF BRICKS FROM CLAY9.4 MANUFACTURE OF BRICKS FROM CLAY(Contd)(Contd)


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