clayproducts-170809040847, B arch architecture

Architecture building construction

1. Clay Products
Building Construction Material

2. Introduction
•Clayisnaturallyoccurringmineralthatis
foundalmosteverywhereonthesurfaceof
theearthmakingthesoilcoverorthesoft
ground.
•Itissowidespreadinitsoccurrencethatin
commonlanguageitisoftenreferredas
earth.

3. Introduction

4. Introduction
•Minerlogicallypureclaymaybecomposed
ofoneormoremineralsofclaygroupsuch
asKaolinite,Montmorillonite,illite,
vermiculiteandAllohane,etc.Kaoliteisthe
mostimportantmineralcomponentofcommon
clays.
•Clayoccursuniversally.Manhasusedthem
sinceancienttimesformakingearthwareof
greatvariety.

5. minerals of clay group

6. Classification of Clays
•Claysareclassifiedintwoways:Genesisor
theirmodeofformationandtheirdominant
characteristics.
•Allclaysareclassifiedintwoways:
•Genesisortheirmodeofformationandtheir
dominantcharacteristics
•TheResidualClays
•TheTransportedClays

7. The Residual Clays

8. Classification of Clays
•TheResidualClayincludesallvarietiesof
claysthatarefoundcoveringtherocksfrom
whichtheyareformedbynaturalprocesses.
Suchclaysarepureintheirchemical
compositionthatisrelatedbroadlytothe
parentrock.ChinaClayisthebestexample
ofresidualClay.

9. Residual Clay

10. Classification of Clays
TheTransportedClays.
•Thesearethemostcommonclaysspreadonthe
earth.Theyareformedbythedisintegrationand
decompositionofthepre-existingrocksbythe
naturalagenciesfollowedbyremovaland
transportationofbrokenpiecestofaroffplaces
wheretheyarefinallydeposited.Henceanysuch
depositoftransportedclaywillhavealltheparticles
transportedfrommanyplacesanddifferentsource
materials.Thetransportedclayare,thereforequite
heterogeneousinmineralogicalandchemical
composition.

11. The Transported Clays.

12. Classification of Clays
•Thetransportedclaysaresometimes
furtherdistinguishedintoglacialclays,
marineclays,alluvialclaysandlacustarine
claywhenglaciers,seas,rivers,andlakes
respectivelyhaveplayeddominantrolesin
theirformation.

13. Classification of Clays
•OntheBasisoftheirdominant
Characteristics,Claysareclassifiedasinto
fourgroups:
•ChinaClay
•FireClay
•VitrifyingClay
•AndBrickClay

14. Classification of Clays
ChinaClay
•Itisthepuresttypeofclaycontainingvery
highpercentageofmineralKaoliniteor
KaolinAl
2Si
2O
5(OH)
4.ItisConsideredhigh
Gradeclayandisusedforthemanufacturing
ofcrockeryandotherproclainware

15. China Clay

16. Classification of Clays
FireClay
•Theyarealsocalledrefractoryclayand
contain,besidesKaolinite,Silicaandalumina
inveryhightemperaturewithoutsufferingany
deformationoffshapegiventothematthetime
ofmoulding.
•Theyaremainlyusedinmanufacturingof
refractorybricksthatareofgreatimportance
inmanymetallurgical,mechanicaland
chemicaloperations

17. Fire Clay

18. Classification of Clays
VitrifiedClays
•Theseclaysarerichinfluxingcompoundslikeironoxide
andcarbonatesofcalciumandmagnesium.Theseare
easilyfusible.i.e.cannotwithstandhightemperatures
above1100
0
Cthefluxesgetsoftenedandformglasslike
materialthatactsasastrongbondingagentbetweenthe
otherclayparticles.Thisresultsintheformationofasmooth
surfacedhardburntclayproducts.
•TheVitrifyingclayscalledhardburntclayarespecially
usedformanufacturingoffacingbrick,flooringtiles,
sewerpipeandothersimilarornamentalanddenseclay
products.

19. Vitrified Clays

20. Classification of Clays
TheBrickClays
•Thesearelowgradeclaysusedmostforthe
manufacturingofbuildingbricksandsimilarclay
products.Brickclayarerichinsilica,alumina,
oxideofiron,calcium,magnesiumandorganic
matter.Itismutualproportionofthesecomponents
thatdefinetheirsuitabilityorotherwiseformaking
goodqualitybricksforbuildingconstruction.
•Theoxidesofiron,calciumandmagnesiumactas
fluxesthatfuseeasilyatbrick-makingtemperatureand
bindthealuminaandsilicaparticlesthoroughlygiving
thebrickdesiredpropertiesofcohesionandstrength.

21. The Brick Clays

22. Bricks
•Buildingbricksmaybedefinedas
“Structuralunitsofrectangularshapeand
convenientsizethataremadeofsuitable
claysbydifferentprocessesinvolving
moulding,drying,andburning.

23. Bricks

24. Bricks
•Itisnowestablishedthateveninremote
ancientcivilizationsbrickswerecommon
materialofconstruction.Itisbelievedthatit
wasinEgyptthatbrickswereusedsome6000
yearsago.Excavationinprehistoricsitesin
ourcountryhasrevealedthatbrickswere
usedabundantlyinIndusvalleycivilization
atMohanjodaroandHarappa.

25. Bricks

26. Bricks
•Evenatpresentbricksisthemostbasicand
favorablematerialforcommonconstruction
throughouttheworld.Thismaybeattributed
tonooffactors:

27. Bricks
Availabilityofclay
•Claysuitableformakingbricksareavailable
almostuniversally.Hencebrickmakingcanbe
adoptedanywhereintheworld.Thisisnottrue
eitherforstonesorforconcretethatarematerial
whichcompetewithclay.

28. Bricks
SizeShapeandhandling
•Bricksaremadeinready–to-usesizesand
shapes.Thisaffordsveryconvenient
handlinganduse.Forstones,however,some
dressingisabsolutelyessential.Incaseof
concrete,anelaborateformworkandshuttering
arebasicrequirements.Moreovertransporting
andlyingofconcretealsorequiresgreatcare,
cautionandexpertise.

29. Bricks

30. Bricks
Cost
•Bricksasalsobrickworkarecheaper
comparedtostonemasonryand
constructionwithconcreteinmostcases.
Thisisbecauseofthefactorsmentionedunder
availability.Sizeandshapeandconstruction
methods

31. Manufacturing of Bricks
•Theprocessofmanufacturingofbricksis
carriedoutinnumberofstagesItIs
essentialasequentialprocess.Thatis,next
stageisreachedonlywhenthepreviousstages
havebeencompletedinallrespect.No
jumpingoveroromissionofstageis
possible.Eachstagehasitsownsignificance
intheprocess.

32. Manufacturing of Bricks

33. Manufacturing of Bricks
TheStagesarelistedbelow:
•Selectionofsuitabletypeofclay
•Preparationandtemperingofmud
•Mouldingofbrickunits
•Dryingofmouldedbricks
•Loadingofdriedbricksinkilns;
•Firingorburningofdriedbricks;
•Coolingoftheunits;
•Unloadingofthekiln;

34. Selection of Suitable Brick Earth
•Agoodtypeofbrickscannotbemadefromevery
typeofclay.Asuitablebrickearthshouldhavethe
followingcompositioninthedesiredproportions:
•1)Alumina(20-30%)Allclaysarechemically
hydrousaluminumsilicates.Thealuminacontentis
responsibleforgivingtheplasticcharactertotheclay
inwetconditions.Whenaluminacontentishigherthan
30%thebricksbecomesmoreplasticandalsoshrink
ondrying.ButifAluminaContentisLessthan20%,
claymaybedifficulttomouldtopropershapes.
HencedesiredcontentofAluminaisabout20–30
%.

35. Alumina (20-30 %)

36. Selection of Suitable Brick Earth
•Silica(50-60%)
•SilicapresentinIdealProportioni.e.50-
60%impartsthequalitiesofhardnessand
strengthtothebricks.Itisalsoresponsible
forresistanceagainstshrinkageanddurability
ofthebricktoweather.Howeverwhilethe
proportionofsilicaareexceptionallyhighin
theclaysuchbrickswhenburntwouldbe
quitebrittleandporous.

37. Selection of Suitable Brick Earth

38. Selection of Suitable Brick Earth
•IronOxide(4-6%)
•ThisOxideactasaflux,i.e.itlowersdown
SofteningtemperatureofSilicaandother
claycomponentsduringfiring.Further,The
IronOxideintheclaysmaymaketheir
burningdifficultandgivethemyellowish
appearance.

39. Iron Oxide

40. Selection of Suitable Brick Earth
•Lime(4-6%)
•ThisComponentsmaketheburningofbricks
quicker.Provided,
•Itshouldnotbemorethan4%,becauseinthis
casemayresultinexcessivesofteningoftheclay
onheating.
•Itmustbepresentonlyinfinepowderform
otherwiseitmaygiverisetoslaking,whichis
harmfulandmaycauseslowdisintegrationof
bricks.

41. Lime

42. Selection of Suitable Brick Earth
•Magnesia
•Whichisinvariablyassociatedwithlime,has
similareffect

43. Constituents &
Desirable quantity
Significance Effects if Excess quantityEffects if lesser
quantity
Alumina(Al
2O
3)(20-30
%):
plasticcharactertotheclaysinwet
conditionsandresistanceagainstshrinkage
ondrying
moreplasticandshrinkmore
ondrying,whichmaydevelop
cracksinondrying.
claymaybedifficult
tomouldinproper
shape
Silica(SiO
2)(50-60%)
freeorcombinedform
Imparthardnessandstrengthtothebrick.
Preventstheshrinkage,crackingand
warpingofrawbricks,soimpartsuniform
shapetothebricks.Durability-depends
uponpropercompositionofsilica.
notbemouldableeasilyand
maynotburneasily.Ifburnt,
wouldbequitebrittleand
porous.
-
Ironoxides(CaCO
3)(4-
6%)
Actsasflux.Redcolourtotheburnt
bricks
causesbricktoosoftduringthe
burningstage,soshapeislost
causeburningdifficult
andalsogives
yellowishappearance
Lime(Fe
2O
3)(4-6%): Makesburningandhardeningofthe
bricksquicker.Itmustbepresentonlyin
powderedandthoroughlydispersedform.If
limeispresentasnodules,itmaygiveriseto
slakingwhenbrickcomesincontactwith
moisture.
notbemorethan5%,because
itmayresultinexcessive
softeningofclayonheating
-
Magnesia(1%orless)Similareffectlikelimesototalpercentage
shouldbeconsider,providesayellowtintto
thebricks
- -

44. Undesirable Components
brickclayshouldbefreefromthefollowing
components:
Thelimemodules:
•obstructtheproperburning,whenbricksare
placedinkiln.
•Ifitpresent,thenburntbricksarelikelytocause
disintegrationofbricksbytheirslakingaction.
Theorganicmatter:
•Rootsofgrasses,leavesandotherorganicmatter,
whichproducescarbononburningwithinthebody
ofbrick.
•Brickdarkerinappearanceandtooporousin
nature,removeinpreparationstage.

45. Undesirable Components
Sulphidesandsulphates:
•Ironsulphideinformofpyriteandalkalkiesinform
ofpotashandsodaareoftenpresentinsomeclays.
•Ironsulphidecausesdisintegrationofthebrickduring
burningstageitself.
Thealkalisalts:
•Actasfluxesduringburningandcreateadditional
softening.
•Ifitispresentinburntbricks,itabsorbsthemoisture
fromtheatmosphereandformthesolutionwithinthe
bodyofbrick.
•Onevaporation,thesesolutionformwhitepatches.This
effectiscalledefflorescence.

46. Field Tests For Brick Earth
•Whenthemanufactureofbrickisonlargescale,
itisalwaysadvisabletogothroughsurveyof
depositsofclayswhichincludemappingofarea
forconsiderabledepthAnalysisofchemical
compositiontestingtheengineeringpropertiesof
thespecimenmadefromsuchearth.
•Suchsurveyassurethetotalquantityand
qualityoftheclay.

47. Field Tests For Brick Earth

48. Field Tests For Brick Earth
Testforconsistency
•Smallsizedballsaremadefromthesoilsbymixingit
withappropriatequantitiesofsandandwater.
•Ballsareallowedtoairdryunderashadedplace.
•Whentheyarecompletelydry,eachballisobservedfor
itsshape,sizeandappearanceofanycracks.
•Ifsoilisofsuitabletype,itwillnotshowany
deformationorcrackinthem.
•Ifsomeshrinkageisthere,wemayvarythemutual
proportionsofsoil,sandandwaterandobservedagain.
•Byvaryingtheseproportion,arightproportionis
foundformakinggoodqualitybricks.
•Ifnegativeresultsareobtainedinallthetrials,itmeans
thebrickclayisnotsuitable.

49. Test For Consistency

50. Test For Moulding Properties
•Testisperformedonthesoilwhichhavepassedtheconsistency
test.
•Soilisthoroughlymixedafteraddingsomemorewaterfor
preparinghomogeneousmud.
•Thinthreads,about3-4mmthickaremadebyrollingbetween
thepalmsoftwohandsfromsmallamountofmudpaste.
•Lengthofsuchthreadsindicatesgoodplasticnatureofthesoil.
•Longerandthinnerthethreads,thesoilisofgoodplasticity
andthreadsbreakquicklyonrollinginnon-plastictypeof
clays.
•Testbricksaremadefromsuchpasteandallowedtodry.Ifthe
corners,edgesandsurfaceshaperemainintactevenafter
drying,thenclayisdescribedassatisfactory.

51. Field Tests For Brick Earth
Testtodeterminedeformationonburning
•Testhelpsinfindingoutapproximateratiooffluxesinthe
clays.
•Testbricksaremadefromthemudpreparedinfirsttwocases.
•Thisbricksareair-dried.
•Burntinapotter’skilnforthreetofivedaysandcooledinair
•Theclaysareofsatisfactoryqualitywhenbricksshow
•Typicalredcolour
•Havemaintainedtheirdimensionsatcornersandedges
•Haveburntuniformly
•Ifburntbricksshowsdefectslikewarpingofsurfaces,twisting
atedgesandswellingatplaces,thebrickclayisconsidered
defectiveandunsuitableformakinggoodbricks.

52. Test to determine deformation on
burning

53. Field Tests For Brick Earth
Strengthtests:
•Ifclayspassesaboveallthetests,thenonlythis
testiscarriedout.
•Fieldtestinvolvesdroppingtheproperlyburnt
bricks,onebyone,fromaheightof2-3meters
onharddrygroundbelow.
•Ifbrickisofgoodquality,thenitshouldeasily
withstandthisshockwithoutbreaking.
•Ifbrickisofpoorquality,thenitbreakeasily
onfallingfromsuchheights.

54. Strength tests

55. Preparation Of Mud
Winning:
•Obtainbrickearthfromitsnaturaldeposit.
•Clearofffromvegetation,pebblesandother
organicmatter.
•Manualdiggingormechanicalexcavationareused
toobtaindrysoilorbrickmatter.
•Clayisspreadonevengroundforseasoningso
thatclayisexposedtoatmosphereforgoodtime.
•Atthisstage,earthisfurthercleanedoffany
pebbles,stoneslimenodulesandvisibleorganic
matter.
•Theseasonedclayisreadyformakingmudby
mixingwithadequateamountofwater.

56. Winning

57. Preparation Of Mud
•Tempering:Convertingthebrickearthtomud
ofproperconsistencybythoroughlymixing
withdesiredquantitiesofwater.
•Manualtempering:Clayisspreadona
platformandthoroughlymixedunderfeetof
eithermanorcattle.
•Waterisaddedgraduallyinsmallquantitiestill
desiredhomogeneityandplasticityare
obtained.
•Pugmilltempering(pugging):mechanical
devicecalledpugmill.

58. Manual Tempering

59. Pug Mill Tempering
•Asimplepugmillconsistofsteelcylinder
coveredattopandholeatornearthebottom.
•Mostimportantpartofpugmillisacentral
verticalshaftprovidedatthebasewhichcan
berotatedwiththehelpoflongarmthrough
animalormotorpower.
•Centralshaftisattachedwiththehorizontal
blades,eachcarriessomeknives.
•Seasonedclayandwaterareaddedfroman
openingprovidedatthetop.
•Thechurningeffecttotheclay-watermixture,
thatisconvertedintomudofdesired
plasticityandconsistency.
•Themudisthentakenoutfromtheholeatthe
baseandnewchargeisfield.

60. Pug Mill Tempering

61. Moulding Of Bricks
•Moulding:istheprocessofmakinggreen
bricksofpropershapeandsizefromthoroughly
temperedclay.
•TwoMainMethods:handmouldingand
machinemoulding.

62. Moulding Of Bricks
•HandMoulding:Usingskilledmanpower.
•MostcommonmethodinIndia.
•Thequalityoftemperedclayiskeptsoft.
•Morewatercontent(18-25%byweight).So,we
cancallthismethodassoftmudprocess.
•Groundmoulding:bricksareshapedfromsuch
asoftmudbyhandonaspeciallyprepared
ground.
•Tablemoulding:bricksareshapedfromsucha
softmudbyhandonaspeciallydesignedtable.

63. Moulding Of Bricks

64. Table Moulding

65. Tools For Hand Moulding
•Abrickmould:
•woodorsteel.
•Itsinsidedimensionsarekeptslightlybigger
thanthedesireddimensionsoffinishedbrick
becausebricksondryingareliabletoshrinkinsize.
•Itmaybeasingleunitoramultipleunittype.
•Thestockboard(mouldingboard):
•Smallwoodenboardwithraisedcentral
projectioncarryingtheidentificationmarks
(frog)ofthemanufacturer.

66. A Brick Mould

67. The Stock Board
(Moulding Board)

68. Tools For Hand Moulding
•ThePallets:
•Thinwoodenplatesusedforhandlingthegreenbricks
fromthemouldingboardstothedryingfield.
•TheStrike:
•Woodormetal
•Hasitsoneedgequitethintoslashsurplusmudfrom
thetopofthemouldedbrick,whileitisinthemould.
•Sometimesathinwirestrunginawoodenblockfor
holdingisusedforthesamepurpose,itiscalledcutting
wire.

69. Tools For Hand Moulding
Wooden mould& Steel mould
Stock board

70. Ground Moulding
•Common methodof
mouldingbricksinIndia
•Astretchoflandisfirst
flattened,levellingand
cleanedandmadesmooth
bymudplastering.
•Somesandissprinkled
uniformlyoverittomake
itnon-sticky.

71. Ground Moulding

72. Ground Moulding
(a)Formakingordinarybricks:
•Mouldiseitherdippedinwater(slopmoulding)or
somesandissprinkledonitsinsidesurface(sand
moulding).
•Mouldisplacedonthegroundatdesiredspot.
•Lumpofmudisdashedintothemouldbyhand.Mud
shouldreachestothesidesandcornersofthemould.
•Anysurplusmudisremovedbyusingthestrikeorthe
cuttingwire.
•Themouldisthenliftedupwithajerkandleaves
behindthemouldedbrickonthegroundbelow.

73. Ground Moulding
•Mouldingbrickswithfrog(palletmoulding)
•Byusingastockboardandpallets.
•Thestockboardisprovidedwitharaisedprojection
carryingtheidentificationmark.
•Themouldisplacedonthestockboard(insteadof
ground)andabrickismoulded.
•Thebrickisthentakenawayusingtwopallettothe
dryingfield.

74. Ground Moulding
•Frog:anidentificationmarkduringthe
mouldingstagewiththehelpofastock
board.Itservesfollowingpurposes:
•Thenameofthemanufactureofthebrickiseasily
foundandcanbeknownforthequalityofthe
brick.
•Thefrog-facedsideisplacedupwardduring
use,whichaccommodatessomeextramortar,
whichdevelopsstructuralgripbetweenupper
andlowerbrick.

75. Frog

76. Table Moulding
•Theskilledworker–mouldercarriesoutall
themouldingoperationsonaspecially
designedtableofsuitabledimensions.
•Tableislargeenoughtoaccommodateallthe
materialsrequiredinhandmouldingsuchas
stockboard,moulds,cuttingedge,water,
sandandtemperedmud.

77. Table Moulding

78. Table Moulding
•Processissimilartopalletmouldingonground.
•Themoulderisplacedonthestockboardandthen
sprinklessomesandinsidethesurfaceofmould.
•Dashesalumpofmudintoit,pressitthoroughlyand
skillfully.
•Cutsawayanysurplusmudwiththestrikeorthecutting
edge.
•Placesapalletoverthemouldandturnitover.
•Themouldedbrickistransferredtothepallet,whichis
carriedawaybyahelper.
•Thisprocessisrepeatedforeachbrick.
•Initialcostisslightlyhigherthangroundmouldingbut
moreefficientandeconomicalinthelongrunbecause
productionisbetterinqualityandquantity.

79. Table Moulding

80. Machine Moulding
•Essentialprocessinallmechanizedbrick
makingplants.
•Cheaperinlongerrunandgivesuniform
qualitybrick.
•Maintwomethods:Stiffmudmethodand
Dryprocessmethod.
•Stiffmudmethod:Smallquantityofwater(8-
12%byvolume)isaddedtotheclaytocreate
plasticity.
•Thisstiffmixismadetopassoutunder
pressurefrommouldingmachine.

81. Machine Moulding

82. Machine Moulding
•Twoversionsofmachinescanbeusedsuchas:
•Wormgearmouldingmachine
•Avacuumpressforbrickmoulding.
Wormgearmouldingmachine:consistsof
•Afeedingchamberprovidedwithawormgearto
applypressure.
•Ahopperatthetoptoreceivetheclaymixfrom
thepugmill
•Afixeddieprovidedatthefrontnarrowend
•Aconveyorbeltonasetofrollers
•Cuttingwiredeviceadjustedinfrontofthedie

83. Worm Gear Moulding Machine
Theoperationstepsonmachineconsistof
•Feedingtheproperlymixedstiffmudintothechamber
throughthehopper
•Forcingforwardthemudchargeusingthewormgear.
Thepressedmudcomesoutthroughthedieintheformof
continuousrectangularribbonhavingtheheightand
widthofthebricks.
Thisribbongetscutintobricklengthsbypressingdownthe
cuttingwiredevice,whentheconveyorbeltisunderthe
device.
Capacityofmachine:1000–2000unitsperhourormore
dependinguponthemachine.

84. Worm Gear Moulding Machine

85. Machine Moulding
•Drypressprocess:averysmallquantityofwateris
addedtofinelycrushedandthoroughlycleanedbatch
ofclay.
•Mixisalmostdry,atbestdamp.
•Suchdampclayisfedthroughhopperstospecialbrick
moulds.
•Pressure-50-150Kg/cm
2
throughhydraulicpresses.
•Thispressureissufficientenoughtoconverttheloose
dampclaymassintodenseandverycompactbrickunit.
•Brickisremovedfromthemould.
•Thesebricksarehavingperfectshapesonallthesides,
edgesandcorners.
•Suchbricksarealsocalledaspressedbricks.

86. Drying Of Bricks
•ReasonsToDryTheGreen
Bricks:
•ToMakeGreenBrick
StrongEnoughToBear
Rough Handling
DuringStackingInThe
KilnForBurning.
•ToAllowLossOf
MoistureAtASlowRate
ToAvoidDisintegration.
•ToSaveFuelDuring
BurningStage.
Drying
Artificial
method
drying in the
chamber
drying in the
tunnel
Natural
method
Air drying
and Sun
drying

87. Drying Of Bricks

88. Drying Of Bricks
•Naturalmethod(stackingmethod):therearetwo
differentstagesinvolvedinthedryingprocess
suchas:
1)Prestackingstage:Mouldedbricksarelaid
sidewiseandflatwisefor2–3daysinthedrying
fields.So,thattheybecomehardenoughto
handleforstackinginheaps.
2)Stackingstage:Bricksarearrangedinthelayers
(100cmwideand10bricklayerheight)byskilled
workers.
•Stakingisdoneinspeciallyprepareddrying
ground.
•Enoughspaceisleftinbetweentheindividual
bricksandbetweenlayers.

89. Natural method (stacking method)

90. Drying Of Bricks
•Artificialdrying:essentialinmechanized
brickmakingunit.
•Independentofweathercondition.
ChamberDrying:
•Arrangeinstacksindryingchamberbykeeping
sufficientspacesforfreecirculationofhotair
aroundthem.
•Hotairiscirculatedundercontrolconditionof
temperatureandhumidity.
•2–4daysormore,andthennextbatchisstacked.

91. Chamber Drying

92. Drying Of Bricks
Tunneldrying:
•Bricksarestackedonmobilecarsthataremadeon
travelonrailswithinaspeciallydesigneddrying
tunnel.
•Thetunnelisdividedintocompartmentsandeach
carismadetostayinaparticularcompartmentfor
pre-fixedduration.
•Thecarscomeoutfromotherend.
•2–3daysforacarloadofbrickstodrytodesired
extent.

93. Tunnel Drying

94. Burning Of Bricks
•Absolutelyessentialtodevelopinbrick
makingthedesiredbuildingproperties
suchassufficientstrength,hardness,
durabilityandresistancetodecayand
disintegration.

95. Burning Of Bricks

96. Burning Of Bricks
•3chemicalchangestakeplaceduring
burningprocess:
•Dehydration:completeremovalofwaterfrom
theporesofthebricks.
•Completedatthetemperaturerangeof425–
765
0
C.
•Lossesallthefreewater.

97. Burning Of Bricks
•Oxidation:itstarttakingplaceduringheating
ofthebricksattheabovetemperatureand
getscompletedatabout650
0
C-900
0
C.
•Alltheorganicmatterinthebrickearthgets
oxidized.Carbonandsulphurareeliminatedas
oxides.
•Fluxes(lime,magnesia,iron)becomereactiveat
thesetemperature.
•Brickacquirestheredcolourduetotheoxidation
ofironintheclay.

98. Burning Of Bricks
•Vitrification:lastreactiontakesplaceat
temperaturerangeof900
0
Cto1100
0
C.
•Thealuminaandsilicastartsofteninginthe
presenceofthefluxingcompounds.
•Theconstituentgrainsgetboundfirmly.

99. Burning Of Bricks
•Brickscanbeburntusing
thefollowingmethods:
(a)ClampBurning
(b)KilnBurning

100. Burning Of Bricks
ClampBurning:
•(OpenkilnorPazawah)
•Temporarystructure,constructedovertheground
•Height-about4to6m.
•Usedforlowerscalebricks,notsuitableinmonsoon
season.
•Trapezoidalinplan,whoseshorteredgeamongthe
parallelsidesisbelowthegroundandslopeangleof
about15⁰
•Averticalbrickandmudwallisconstructedatthe
loweredgetosupportthestackofthebrick.

101. Clamp Burning

102. Burning Of Bricks
•ClampBurning:
•(OpenkilnorPazawah)
•Firstlayer-fuelislaidasthebottommost
layerwiththecoal,woodandotherlocally
availablemateriallikecowdungandhusk.
•Anotherlayer-4to5rowsofbricks
•Thenagainafuellayerislaidoverit.
•Thicknessofthefuellayerdecreaseswiththe
heightoftheclamp.
•Topsurface-coveredwiththemudsoasto
preservetheheat.
•Fireisignitedatthebottom,oncefireisstarted
itiskeptunderfirebyitselfforoneortwo
monthsandsametimeperiodisneededfor
thecoolingofthebricks.
•Inaclampof10m*7.5msides,aboutone-
lakhbrickscanbeburntintwomonths.

103. Burning Of Bricks
•Advantages of Clamp Burning:
•Easy to erect and operate
•Any type of fuel can be used
•Not requires skilled labourand least supervision after
burning
•Economical
•Clamp is not liable to injury from high wind or
rain

104. Burning Of Bricks
•DisadvantagesofClampBurning:
•Burningofbricksisnotuniform,suchasbricksatthe
bottomareover-burntwhileatthetopareunder-burnt.
•Bricksloosetheirshape,andreasonmaybetheir
descendingdownwardoncethefuellayerisburnt.
•Thismethodcannotemployedforthemanufacturing
oflargenumberofbricksanditiscostlyintermsoffuel
becauselargeamountofheatiswasted.
•Itcannotbeemployedinmonsoonseason.
•Timerequiredforburningistoolong.
•Nopossibilitytoregulateheat,onceitstartburning.

105. Burning Of Bricks (Kiln Burning)
•Kilnsarepermanentstructures,usedforburning.
•Fuel-Coalandotherlocallyavailablematerialslike
wood,cowdungetc.
•Twotypesbasedontheirprincipleofconstruction:

106. Burning Of Bricks (Kiln Burning)
IntermittentKilns:periodickilns,onlyoneprocesscantakeplaceatone
time.
•Thebricksupplyfromsuchkilnsisintermittentandnot
continuous.
•e.g.TheAllahabadkiln
ContinuousKilns:possibletogetsupplyofbricksalmostcontinuously.
•Usedwhenthebricksaredemandedinlargerscaleandinshort
time.
•Operationsinthesechambersaresocontrolledthatatanygiven
time,whenonechamberisintheloadingprocess,anotherchamber
maybeinburningstage,thirdchamberinthepreheatingstage,
fourthchamberinthecoolingstageandfifthchamberinthe
unloadingorsupplystage.
•e.g.TheBull’strenchkiln,TheHoffman’scontinuouskiln,The
Tunnelkiln.

107. Burning Of Bricks
(Kiln Burning)
IntermittentKiln
•Rectangular,FourPermanentWalls.
•TotallyUndergroundOrPartlyUndergroundAndPartlyOver
Ground.
•TheLongerWallsAreRaisedPerpendicularToTheDirectionOf
PrevailingWinds.
•ProvidedWithNumberOfOpeningCalledFlues(F),ExactlyOppositeTo
EachOtherForChargingFuelsAndControllingAir.
•OpeningsAreProvidedWithDoorSheets,WhichCanBeRaisedOr
Lowered.
•TheShorterWallsAreProvidedWithDoorsForLoadingAndUnloading
TheBricks.
•ThereAreFourStagesInTheWorkingOfKiln:
•Loading
•Firing
•Cooling
•Unloading

108. Intermittent Kiln

109. Burning Of Bricks
(Kiln Burning)
Loading:driedbricksarelaidinrowsonthe
raisedportions.
•Eachrow-twotothreebrickthick.
•Height-8to10bricklayers.
•Bricklayinginsuchamannerthat
makearch-shapedopeningfor,
a)supplyoffuelb)supplyofair
•Whilestaking,somespaceisprovided
betweenindividualbricksforcirculation
ofairaroundeachbrick.
•Toplayer-coveredwiththicklayerof
dryearth,whichhelpsinpreventing
escapeofheatfromthekilnduringthe
burningprocess.

110. Burning Of Bricks
(Kiln Burning)
Firing:Afterloading,fuelissuppliedintheopeningatthe
base,isfiredthroughthearchshapedopeningprovided
forthispurpose.
•Lowfires:1–2daysforremovingmoistureleftinthe
brickduringtheprocessofdrying.
•Firingisbroughttofullstrength.
•Theflamesspreadupwardbakingandburningthe
bricksstackedwithinthebodyofthekilnin2–3days
time.

111. Burning Of Bricks
(Kiln Burning)
Cooling:Aftervisualinspectionand
ensuringthatallthefuelhasbeenburnt,
thekilnopeningsareclosedfor7–10
days,whichhelpsinnaturalslow
coolingoftheburntlotofbricks.
•Slowcoolingisessentialfor
avoidingdevelopmentofcracksin
thecoolingbricks.
•Ifcoolingatfastrate,cracksare
likelytooccurandspoilthebrick.
Unloading:aftersufficientcooling,the
toplayerofthedustisremoved.
•Burntbricksareremovedfromthe
toplayertodownwards.
•Theentirekilnisemptiedand
thoroughlycleanforloadingnext
batch.

112. Burning Of Bricks
(Kiln Burning -The Bull’s Trench Kiln)
•Principle:continuoustypeofkiln.
•Numberofcompartments,whichcanbeoperated
insequentialprocess.
•Possibletoobtainaregularsupplyofburnt
bricks.

113. Burning Of Bricks
(Kiln Burning -The Bull’s Trench Kiln)
•Construction:rectangular,circularorovalshapeinthe
plan.
•Belowthegroundlevelbyexcavatingatrenchoftherequired
widthforthegivencapacityofbrickmanufacturing.
•Rangeofdimensionoftrenchdependinguponthedesired
capacityofthebricks:
–Length:50–78m
–Width:6–8m
–Depth:1–2m
•Atypicaltrenchkilnhastwowalls:
–Innerwall-continuousandclosecontactwiththeinnerlandpart.
–Outerwall-numberofopeningsorgatesprovidedwithdampersor
doorswhichcanbeopenedorclosed.

114. Burning Of Bricks
(Kiln Burning -The Bull’s Trench Kiln)

115. Burning Of Bricks
(Kiln Burning -The Bull’s Trench Kiln)
•ThisTrenchisdividedgenerallyin12chamberssothat2
numbersofcyclesofbrickburningcantakeplaceatthe
sametimeforthelargerproductionofthebricks.
•Thestructureisunder-groundsotheheatisconservedtoa
largeextentsoitismoreefficient.
•Oncefireisstarteditconstantlytravelsfromonechamber
totheotherchamber,whileotheroperationslikeloading,
unloading,cooling,burningandpreheatingtakingplace
simultaneously.
•Suchkilnsaregenerallyconstructedtohaveamanufacturing
capacityofabout20,000bricksperday.
•Drawback:notapermanentroof,soitisnoteasyto
manufacturethebricksinthemonsoonseasons.

116. Burning Of Bricks
(Kiln Burning -The Bull’s Trench Kiln)

117. Burning Of Bricks
(Kiln Burning -The Bull’s Trench Kiln)

118. Burning Of Bricks
(Kiln Burning -The Bull’s Trench Kiln)
•Working:
•firstpreparetokeepallcompartmentsofthe
kilninoperation.
•Eachcompartmenthastopassthroughfollowing
sixstagessuchasloading,unloading,cooling,
burning,preheatingandcleaning.

119. Burning Of Bricks
(Kiln Burning -The Bull’s Trench Kiln)
•Loading:
•stackingofbrickisdonecarefullywithinthekiln
boundaries
•Enoughspaceisleftbetweenanytwobricksinalayer
forfreecirculationofhotgases.
•Fuelgalleriesaremadeinthelowerregionsthatare
continuouswiththefluesintheoutsidewall.
•Verticalflues(holes)areleftconnectingthefuelgalleries
andhorizontalflues.Theseholesshouldbeleftat
approximatelyeverymeterduringloading.
•Archedopeningsareleftattheendforplacingthechimney.

120. Burning Of Bricks
(Kiln Burning -The Bull’s Trench Kiln)
•Thetopoftheloadedsectionisthoroughly
coveredwith20–30cmdeeplayerofashand
dust.
•Metalplatesmaybeplacedoverthemduring
theoperationtocoverthetop.

121. Burning Of Bricks
(Kiln Burning -The Bull’s Trench Kiln)
•Preheating:
•hotandwastegasesfromaprecedingburningchamber
aremadetopasstotheloadedchamberbyraisingthe
dampersbetweenthetwochambers.
•Gasesarenotveryhot.
•Tomakethebrickscompletelydryandmakethemreadyfor
finalburning.
•Burning:
•requiredvolumeofairissuppliedbyregulatingthe
openingbyraisingofthegatesprovidedintheouterwall.
•Additionalquantitiesoffuelmaybeaddedfromtheflues
providedatthetop.
•24–30hoursforperfectburning.

122. Burning Of Bricks
(Kiln Burning -The Bull’s Trench Kiln)
•Cooling:
•Alltheoutergatesareclosedbyloweringthedampers.
•Theinterdepartmentalgatesareopenedupforleading
thehotgasestothepreheatingsection.
•3–4daystocooldowncompletelybeforeunloading.
•Unloading:
•Thetoplayerofashanddustarefirstremovedfromthetop
ofthesection.

123. Burning Of Bricks
(Kiln Burning -The Bull’s Trench Kiln)
•Advantages:
1)Costoffuelislessasheatofhotgasesisfully
utilizedforpre-heatingofbricks
2)Continuoussupply
3)Highpercentageoffirstclassbricks
•Disadvantages:
1.Highinitialcost
2.Constantskilledsupervisionisessential

124. Burning of bricks
(Kiln Burning -The Hoffman’s continuous kiln)
•Principle:modernandmorerefined
typeofbrickkiln.
•Forlargenumberofbricks.
•Controlconditionoftemperature.

125. Burning of bricks
(Kiln Burning -The Hoffman’s continuous kiln)
Construction:overground
•Itissometimesknownasflamekiln.
•Circularinplananditisdividedintoa12numberofchambers.
•Permanentroof-canbeworkedthroughouttheyear.
•Theadjacentchambersareinterconnectedbydoorswhich
canbeopenorclosedbyraisingorloweringdampers.
•Centralchimneyisprovided,whichisconnectedtoalltwelve
chamber.
•Eachchamberisalsoprovidedwithseparategateintheouter
wallthroughwhichitcanbeloaded,unloadedandfired.

126. Burning Of Bricks
(Kiln Burning -The Hoffman’s Continuous Kiln)
•Working:atanytime,somechamberscanbein
burning,otherinthepreheating,stillothersin
coolingandsomeintheunloadingstage.
•Themostimportantconditionfortheworkingis
establishmentofupwardcurrentofairwithinthekiln,
whichcanbedonebyclosingalltheoutergatesexcept
ofthechamber,whichisbeingunloaded.
•Naturalairentersthekilnthroughthisgates.

127. Burning Of Bricks
(Kiln Burning -The Hoffman’s Continuous Kiln)

128. Burning Of Bricks
(Kiln Burning -The Hoffman’s Continuous Kiln)
•Itismadetopassthroughdifferentchambersby
openingtheirinterconnectingdoors.
•Theflueatthebackofeachchamberiskeptclosed.
•Theairwilldothejobofcooling,burningandpre-
heating.
•Theairisthenenterthechimneyforpre-heatingstage.
•Aschemeofcyclicoperationispreparedinadvancefor
working.
•Therearemanypossibilities.Basedontimerequirement
foreachstage,wecandecidetheoperationofthekiln.

129. Burning of bricks
(Kiln Burning -The Hoffman’s continuous kiln)
•Advantages:
1.Highpercentageoffirstclassbricks
2.Regularout-turnofbricks
3.Bricksareevenlyburnt
4.Economyinfuelasalltheheatofcombustionis
utilized
•Disadvantages:
1.Highinitialcost
2.Constantskilledsupervisionisessential
3.Economydemandsregularconsumptionofits
output,whichmaynotbepossibleeverywhere.

130. Burning Of Bricks
(Kiln Burning -The Tunnel Kiln)
•Informoftunnel.
•Continuoustypeand
highlyefficient.
•Thetunnelisprovidedwith
railtracksforcars.
•Rawbricksareplacedin
trolleyswhicharethen
movedfromoneendtothe
otherendoftunnel.

131. Burning Of Bricks
(Kiln Burning -The Tunnel Kiln)
•Threesections:pre-heatingsection,theburningsectionand
thecoolingsection.
•Thecarloadedwithrawbricksismovedintothepre-
heatingchamber.Thebricksareheatedbythewaste
gasescomingfromtheburningsection.
•Afterfewhoursstop,thecarismovedintotheburning
chamberfor20to24hrs.
•Thenthecarismovedtothecoolingchamber.
•Whenbricksaresufficientlycooled,theyareunloaded.
•Thekilnprovestobeeconomicalwhenthebricksare
manufacturesonalargescale.
•Astemperatureisundercontrol,uniformbricksof
betterqualityareproduced.

132. COMPARISON BETWEEN CLAMP -BURNING AND
KILN-BURNING
No. Item Clamp-burning Kiln-burning
1. CapacityAbout 20000 to 100000 bricks can be prepared at a
time.
Average 25000 bricks can be prepared per day.
2.Cost of fuelLow as grass, cow dung, litter, etc. may be used.Generally high as coal dust is to be used.
3.Initial costVery low as no structures are to be built.More as permanent structures are to be
constructed.
4.Quality of bricksPercentage of good quality bricks is small about
60% or so.
Percentage of good quality bricks is more about
90% or so.
5.Regulation of fireIt is not possible to control or regulate fire during
the process of burning
Fire is under control throughout the process of
burning.
6. Skilled
supervision
Not necessary throughout the process of burning.Continuous skilled supervision is necessary.
7. Structure Temporary structure. Permanent structure.
8.SuitabilitySuitable when bricks are to be manufactured on a
small scale and when the demand of bricks is not
continuous.
Suitable when bricks are to be manufactured on
a large scale and when there is continuous
demand of bricks.
9.Time of burning
and cooling.
It requires about 2 to 6 months for burning and
cooling of bricks.
Actual time for burning of one chamber is
about 24 hours and only about 12 days are
required for cooling of bricks.
10.Wastage of
heat.
There is considerable wastage of heat from top and
sides and hot flue gas is not properly utilized.
Hot flue gas is used to dry and pre-heat raw
bricks. Hence wastage of heat is the least.

133. Comparison Between Bull’s Trench And
HoffmansKiln
No. Item Bull’s Trench kiln Hoffman’s kiln
1.ContinuitySemi-continuousin strict sense
because it has no roof and can not
burn bricks during monsoon.
Perfect, because it has a
permanentroof and burning
operations can be carried out
through out the year.
2.Initial costLow,because construction is
ordinary type.
High, because construction
requires perfect designing and
high quality material.
3.Operating
cost
Higher,because quantity of fuel
consumed is more and
conservation of heat is less.
Lower, because maximum
conservation of heat is possible
in this type of kiln
4.Quality of
bricks
Ratioof best quality to total bricks
is less.
Ratioof best quality to total
bricks is quite high.
5SuitabilitySuitable for low investment
production of bricks
Most suitable for semi
mechanized and mechanized
production

134. References
•BuildingConstruction:DrB.C.Punmia
•CivilEngineeringMaterial:Prof.Singh
•InternetWebSites

135. Thanks…