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Development of Light Weight Concrete

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Development Of Light Weight Concrete journal paper
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engineeringcivil.com http://www.engineeringcivil.com/developmentoflightweightconcrete.html Development Of Light Weight Concrete By Dhawal Desai IIT Bombay ABSTRACT This paper deals with the development of two types of lightweight concrete the one using lightweight aggregate (Pumice stone) and the other water floating type using Aluminium powder as an air entraining agent. This also shows the importance of water/cement ratio as in first type of concrete it relates to the smoothness of the surface and in second one it is a major factor which controls the expansion of concrete. INTRODUCTION: Lightweight concrete can be defined as a type of concrete which includes an expanding agent in it that increases the volume of the mixture while reducing the dead weight. It is lighter than the conventional concrete with a dry density of 300 kg/m 3 up to 1840 kg/m 3 . The main specialties of lightweight concrete are its low density and low thermal conductivity. There are many types of lightweight concrete which can be produced either by using lightweight aggregate or by using an air entraining agent. In this project I have worked on each of the above mentioned types. Both of them are nonstructural concrete. 1) By using Pumice stone as a lightweight aggregate: Pumice stone is a lightweight aggregate of low specific gravity. It is a highly porous material with a high water absorption percentage. In this we do not use the conventional aggregate and replace it by the pumice stone. 2) By using Aluminium powder as an air entraining agent: Water floating aerated concrete is made by introducing air or gas into slurry composed of Portland cement and sand, so that when the mix sets and hardens, uniform cellular structure is formed. Thus it is a mixture of water, cement and finely crushed sand. We mix fine powder of Aluminium to the slurry and it reacts with the calcium hydroxide present in it thus producing hydrogen gas. This hydrogen gas when contained in the slurry mix gives the cellular structure and thus makes the concrete lighter than the conventional concrete. ADVANTAGE: Lightweight concrete is of utmost importance to the construction industry. The advantages of lightweight concrete are its reduced mass and improved thermal and sound insulation properties, while maintaining adequate strength. The marginally higher cost of the lightweight concrete is offset by size reduction of structural elements, less reinforcing steel and reduced volume of concrete, resulting in overall cost reduction. The reduced weight has numerous advantages; one of them is reduced demand of energy during construction. TYPES OF LIGHTWEIGHT CONCRETE: Using lightweight aggregates: This type is produced using lightweight aggregate such as volcanic rock or expanded clay. It can be produced with the use of naturally mined lightweight aggregates (bulk density in the range of 880 kg/m 3 ) or manmade lightweight aggregates like “Aardelite” or “Lytag” (bulk density 800 kg/m 3 ). Using foaming agents: This one is produced through the addition of a foaming agent in cement mortar. This creates a fine cement matrix which has air voids throughout its structure. Aerated cement mortar is
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  • engineeringcivil.com http://www.engineeringcivil.com/developmentoflightweightconcrete.html

    DevelopmentOfLightWeightConcrete

    ByDhawalDesaiIITBombay

    ABSTRACTThispaperdealswiththedevelopmentoftwotypesoflightweightconcretetheoneusinglightweightaggregate(Pumicestone)andtheotherwaterfloatingtypeusingAluminiumpowderasanairentrainingagent.Thisalsoshowstheimportanceofwater/cementratioasinfirsttypeofconcreteitrelatestothesmoothnessofthesurfaceandinsecondoneitisamajorfactorwhichcontrolstheexpansionofconcrete.

    INTRODUCTION:Lightweightconcretecanbedefinedasatypeofconcretewhichincludesanexpandingagentinitthatincreasesthevolumeofthemixturewhilereducingthedeadweight.Itislighterthantheconventionalconcretewithadrydensityof300kg/m3upto1840kg/m3.Themainspecialtiesoflightweightconcreteareitslowdensityandlowthermalconductivity.

    Therearemanytypesoflightweightconcretewhichcanbeproducedeitherbyusinglightweightaggregateorbyusinganairentrainingagent.InthisprojectIhaveworkedoneachoftheabovementionedtypes.Bothofthemarenonstructuralconcrete.

    1)ByusingPumicestoneasalightweightaggregate:Pumicestoneisalightweightaggregateoflowspecificgravity.Itisahighlyporousmaterialwithahighwaterabsorptionpercentage.Inthiswedonotusetheconventionalaggregateandreplaceitbythepumicestone.

    2)ByusingAluminiumpowderasanairentrainingagent:WaterfloatingaeratedconcreteismadebyintroducingairorgasintoslurrycomposedofPortlandcementandsand,sothatwhenthemixsetsandhardens,uniformcellularstructureisformed.Thusitisamixtureofwater,cementandfinelycrushedsand.WemixfinepowderofAluminiumtotheslurryanditreactswiththecalciumhydroxidepresentinitthusproducinghydrogengas.Thishydrogengaswhencontainedintheslurrymixgivesthecellularstructureandthusmakestheconcretelighterthantheconventionalconcrete.

    ADVANTAGE:Lightweightconcreteisofutmostimportancetotheconstructionindustry.Theadvantagesoflightweightconcreteareitsreducedmassandimprovedthermalandsoundinsulationproperties,whilemaintainingadequatestrength.Themarginallyhighercostofthelightweightconcreteisoffsetbysizereductionofstructuralelements,lessreinforcingsteelandreducedvolumeofconcrete,resultinginoverallcostreduction.Thereducedweighthasnumerousadvantagesoneofthemisreduceddemandofenergyduringconstruction.

    TYPESOFLIGHTWEIGHTCONCRETE:Usinglightweightaggregates:Thistypeisproducedusinglightweightaggregatesuchasvolcanicrockorexpandedclay.Itcanbeproducedwiththeuseofnaturallyminedlightweightaggregates(bulkdensityintherangeof880kg/m3)ormanmadelightweightaggregateslikeAardeliteorLytag(bulkdensity800kg/m3).

    Usingfoamingagents:Thisoneisproducedthroughtheadditionofafoamingagentincementmortar.Thiscreatesafinecementmatrixwhichhasairvoidsthroughoutitsstructure.Aeratedcementmortaris

  • producedbytheintroductionofagasintocementitiousslurrysothatafterhardeningacellularstructureisformed.

    TYPESOFLIGHTWEIGHTAGGREGATE:Lightweightaggregatesusedinstructurallightweightconcretearetypicallyexpandedshale,clayorslatematerialsthathavebeenfiredinarotarykilntodevelopaporousstructure.Otherproductssuchasaircooledblastfurnaceslagarealsoused.Alsotherearesomenonstructurallightweightaggregateswithlowerdensitymadewithotheraggregatematerialsandhigherairvoidsinthecementpastematrix.Thesearetypicallyusedfortheirinsulationproperties.

    Naturalaggregates:InorganicNaturalAggregates:Diatomite,pumice,scoriaandvolcaniccindersarenatural,porousvolcanicrockswithabulkdensityof500800kg/m3whichmakeagoodinsulatingconcrete

    OrganicNaturalAggregates:Woodchipsandstrawcanbemixedwithabindertoprovidealightweightnaturalaggregate.Thesearecellularmaterialswhichhaveairtrappedwithintheirstructuresoncetheyhavelowmoisturecontent.

    Manufacturedaggregates:1.Bloatedclay,sinteredflyashandfoamedblastfurnaceslag.2.Lightweightexpandedclayaggregate:Thisisproducedbyheatingclaytoatemperatureof10001200oC,whichcausesittoexpandduetotheinternalgenerationofgasesthataretrappedinside.Theporousstructurewhichformsisretainedoncoolingsothatthespecificgravityismuchlowerthanwhatwasbeforeheatingit.

    Foamingagents:Therearesomefoamingagentswhichwhenaddedtothecementslurryformsairvoidsthroughoutitsstructure.Alsotherearesomeagentswhoreactwiththechemicalspresentinthecementslurryandevolvegaseswhichresultsintheexpansionoftheslurryandwhenithardens,leavesairvoidsintheconcretethusmakingitlighterthanthenormalconcrete.

    Thebulkdensityoffinelightweightaggregatesisaround1200kg/m3.Thebulkdensityofcoarselightweightaggregatesisaround960kg/m3.

    GENERALPROPERTIES:LightWeight:Densityrangefrom650Kg/m3to1850Kg/m3ascomparedto1800Kg/m3to2400Kg/m3forconventionalbrickandconcreterespectively.Despitemillionsoftinyairfilledcells,itisstronganddurable.ThereisLightweightadvantageforthestructuredesign,leadingtosavingsinsupportingstructuresandfoundation.

    CompressiveStrength:2.0to7.0N/mm2.

    ExcellentAcousticPerformance:Itcanbeusedaseffectivesoundbarrierandforacousticsolutions.Hence,highlysuitableforpartitionwalls,floorscreens/roofingandpanelmaterialinauditoriums.

    EarthquakeResistant:Sincelighterthanconcrete&brick,thelightnessofthematerialincreasesresistanceagainstearthquake.

    Insulation:Superiorthermalinsulationpropertiescomparedtothatofconventionalbrickandconcrete,soreducestheheatingandcoolingexpenses.Inbuildings,lightweightconcretewillproduceahigherfireratedstructure.

    Workability:Productsmadefromlightweightconcretearelightweight,makingthemeasytoplaceusingless

  • skilledlabour.Thebrickscanbesawed,drilledandshapedlikewoodusingstandardhandtools,regularscrewsandnails.Itissimplerthanbrickorconcrete.

    Lifespan:Weatherproof,termiteresistantandfireproof.

    SavingsinMaterial:Reducesdeadweightoffillerwallsinframedstructuresbymorethan50%ascomparedtobrickworkresultinginsubstantialsavings.Duetothebiggeranduniformshapeofblocks,thereisasavinginbedmortarandplasterthickness.Inmostcasesthehighercostofthelightweightconcreteisoffsetbyareductionofstructuralelements,lessreinforcingsteelandreducedvolumeofconcrete.

    WaterAbsorption:Closedcellularstructuresandhencehavelowerwaterabsorption.

    SkimCoating:Donotrequireplasterandwaterrepellentpaintsuffices.Wallpapersandplasterscanalsobeapplieddirectlytothesurface.

    ModulusofElasticity:Themodulusofelasticityoftheconcretewithlightweightaggregatesislower,0.50.75tothatofthenormalconcrete.Thereforemoredeflectionisthereinlightweightconcrete.

    MANUFACTURING:Itisproducedbyincludinglargequantitiesofairintheaggregate,matrixorinbetweentheaggregateparticlesorbyacombinationoftheseprocesses.Lightweightaggregatesrequirewettingpriortousetoachieveahighdegreeofsaturation.Iftheaggregatesarentfullysaturatedtheyhaveatendencytofloattowardsthesurfaceofthemixafterithasbeenplaced.

    Duetothehighermoisturecontentoflightweightconcrete,dryingtimesaretypicallylongerthanregularconcrete.Typically,a0.5watertocementratioslurryisusedasabasemixtureforlightweightconcrete.Thewatercementratiovariesaccordingtospecificprojectrequirements.

    Notethatlightweightconcreteobtainsitsnaturalfluidityfromtheairbubblestructure,notfromexcesswatercontent.

    EffectofaddingFlyash:Flyashaddedtothecementdoesnotadverselyaffectthebasichardenedstateoflightweightconcrete.Infusingandsupportingthelightweightconcretewiththeaircellsystemisamechanicalactionandisnotproblematicwithflyashorotheradditives.NotethatsomeflyashmixesmaytakelongertosetthanpurePortlandcementapplications.

    USES:Theprimaryuseoflightweightconcreteistoreducethedeadloadofaconcretestructurewhichthenallowsthestructuraldesignertoreducethesizeofcolumns,footingandotherloadbearingelements.Sothemarginallyhighercostofthelightweightconcreteisoffsetbythesizereductionofstructuralelements,lessreinforcingsteelandreducedvolumeofconcrete,thusresultinginloweroverallcost.

    Theycanalsobeusedforfireprotection,wheretheycanshieldstructuralsteelfromfire.Theyarealsousedasaninsulatingblock.

    Lightweightconcretehasbeenusedtoconstructextremelylargecantilevers,asthemembercanbenarrowerduetothedecreaseddeadload.Usingconcreteofalowerdensityresultsinalowerdeadloadandcanresultinsavingsduetosmallermembersizes.Occasionallythiscanallowconstructionongroundwithalowloadbearingcapacity.

    Theporosityoflightweightaggregateprovidesasourceofwaterforinternalcuringoftheconcretethatprovidescontinuedenhancementofconcretestrengthanddurability,butthisdoesnotpreventtheneedforexternalcuring.

    Structurallightweightconcretehasbeenusedforbridgedecks,piersandbeams,slabsandwallelements

  • inconcreteandsteelbuildings,parkingstructures,tiltupwalls,toppingslabsandcompositeslabsonmetaldecking.

    Note:Theconcretecovertoreinforcementusinglightweightaggregatesinconcreteshouldbeadequate.Usuallyitis25mmmorethanthatofnormalconcretebecauseofitsincreasedpermeabilityandalsoconcretecarbonatesrapidlybywhichtheprotectiontothesteelbythealkalinelimeislost.

    AUTOCLAVEDAERATEDCONCRETEUSINGALUMINIUMPOWDER(AAC)AutoclavedAeratedConcrete(AAC)orAutoclavedLightweightConcrete(ALC)isaprecastconstructionmaterialthatismadefromavarietyofaggregatepartsnolargerthansand.Atroughlyonefifthoftheweightofnormalconcrete,itisanincrediblylightweightbuildingmaterial.Itprovidesexcellentthermalandacousticresistanceandalsoprotectsagainsthouseholdhazardsastermitesandfire.AACiscommonlyreferredtoasautoclavedcellularconcretebecausehydrogenbubblesformduringtheproductionprocess,resultinginsmallpocketsofairwithintheconcretethatsubstantiallyincreasethevolumeofthefinalconcreteproduct.Thoughtheprecisecompositionofautoclavedaeratedconcretemayvary,itisgenerallymadeupofquartzsandorsomeotherfineaggregate,cementandwaterorsomeotherbindingcomponentandaluminiumpowder.Thealuminiumpowderreactswiththecementandformshydrogenbubblestoformwithinthemix,therebyincreasingthevolumetoweightratiooftheconcretemix.Afterthemixiscastintothedesiredformandthevolumeincreasingchemicalreactionsoccur,theconcretemix,whichisstillsoft,isautoclaved.

    MANUFACTURINGPROCESS:Therawmaterialsarebatchedbyweightanddeliveredtothemixer.Measuredamountsofwaterandexpansiveagentareaddedtothemixerandthecementitiousslurryismixed.

    SteelmouldsarepreparedtoreceivethefreshAAC.IfreinforcedAACpanelsaretobeproduced,steelreinforcingcagesaresecuredwithinthemoulds.Aftermixing,theslurryispouredintothemoulds.Theexpansiveagentcreatessmall,finelydispersedvoidsinthefreshmixture,whichincreasesthevolumebyabout50percentinthemouldswithinthreehours.

    Withinafewhoursaftercasting,theinitialhydrationofcementitiouscompoundsintheAACgivesitsufficientstrengthtoholditsshapeandsupportitsownweight.Aftercutting,theaeratedconcreteproductistransportedtoalargeautoclave,wherethecuringprocessiscompleted.Autoclavingisrequiredtoachievethedesiredstructuralpropertiesanddimensionalstability.Theprocesstakesabouteightto12hoursunderapressureofabout174psi(12Bars)andatemperatureofabout180oC.

    TECHNICALSPECIFICATIONS:Density:300to1600kgpercumthisislightenoughtofloatinwaterCompressivestrength:300to900psiAllowableshearstress:8to22psiThermalresistance:0.8to1.25perin.ofthicknessSoundTransmissionClass(STC):40for4in.thickness45for8in.thickness

    TECHNICALPERFORMANCE:FireResistance:Autoclavedaeratedconcreteprovidesthehighestsecurityagainstfireandmeetsthemoststringentfiresafetyrequirements.Duetoitspurelymineralcomposition,AACisclassifiedasanoncombustiblebuildingmaterial.Itisbothresistanttofireupto1200oCandheatresistant.

    StructuralPerformance:Autoclavedaeratedconcreteisstronganddurabledespiteitslightweight.AACssoliditycomesfromthecalciumsilicatethatenclosesitsmillionsofairporesandfromtheprocessofcuringinapressurizedsteamchamber,anautoclave.Itsexcellentmechanicalpropertiesmakeittheconstructionmaterialofchoiceforearthquakezones.

  • SoundInsulation:AAChasexcellentsoundinsulationpropertiescomparedtootherbuildingmaterialswiththesameweight.

    Durability:Itretainsitspropertiesfortheentirelifeofabuildingandcanresistwind,earthquake,rain(alsoacidrain),stormandawiderangeofexternaltemperatures.

    ADVANTAGES:Ithasbeenrefinedintoahighlythermallyinsulatingconcretebasedmaterialusedforbothinternalandexternalconstruction.BesidesAACsinsulatingcapability,oneofitsadvantagesinconstructionisitsquickandeasyinstallation,forthematerialcanberouted,sandedandcuttosizeonsiteusingstandardcarbonsteelbandsaws,handsawsanddrills.

    SustainableConstructionThechoiceoftherightbuildingmaterialisoneofthekeyfactorsforsustainablebuildings.AACisabuildingmaterialwhichoffersconsiderableadvantagesoverotherconstructionmaterials.Itshighresourceefficiencygiveslowenvironmentalimpactinallphasesofitslifecycle,fromtheprocessingofrawmaterialstothedisposalofAACwaste.

    EnvironmentalPerformance:Resources:AACismadefromnaturallyoccurringmaterialsthatarefoundinabundancelime,finesand,othersiliceousmaterials,waterandasmallamountofaluminiumpowder(manufacturedfromabyproductofaluminium).FurthermoretheproductionofAACdemandsrelativelysmallamountsofrawmaterialsperm3ofproduct,anduptoafifthasmuchasotherconstructionproducts.

    Environmentalimpactduringproduction:Norawmaterialsarewastedintheproductionprocessandallproductionoffcutsisfedbackintotheproductioncircuit.ThemanufactureofAACrequireslessenergythanforallothermasonryproducts,therebyreducinguseoffossilfuelsandassociatedemissionsofcarbondioxide(CO2).Industrialqualitywaterisusedandneitherwaternorsteamisreleasedintotheenvironment.Notoxicgasesarecreatedintheproductionprocess.

    Environmentalimpactduringuse:AACsexcellentthermalefficiencymakesamajorcontributiontoenvironmentalprotectionbysharplyreducingtheneedforspaceheatingandcoolinginbuildings.

    Inaddition,AACseasyworkabilityallowsaccuratecuttingthatminimizesthegenerationofsolidwasteduringuse.ThefactthatAACisuptofivetimeslighterthanconcreteleadstosignificantreductionsinCO2emissionsduringtransportation.

    Reuse,recoveryanddisposal:ThroughoutthelifecycleofAAC,potentialwasteisreusedorrecycledwhereverpossibletominimizefinaldisposalinlandfill.WhereAACwasteissenttolandfill,itsenvironmentalimpactisminorsinceitcontainsnotoxicsubstances.

    DISADVANTAGES:Autoclavedaeratedconcreteisnotwithoutitsdisadvantages.Forexample,itisnotasstrongaslessporousvarietiesofconcrete,soitmustoftenbereinforcedifitistobeusedforintenseloadbearingwork.Thoughitcanbeshippedjustaboutanywherewithrelativeeasebecauseofitslightweight,autoclavedaeratedconcreteisnotwidelyproduced,soitmaybedifficultformanytoobtainitlocally.Itmustalsobecoatedwithsomeformofprotectivematerial,asittendstodegradeovertimebecauseofitsporousnature.

    USES:Itisalightweight,precastbuildingmaterialthatsimultaneouslyprovidesstructure,insulation,andfireandmouldresistance.AACproductsincludeblocks,wallpanels,floorandroofpanelsandlintels.

    USEOFALUMINIUMPOWDER:Thereactantsinaeratedconcretearelime(whichispresentincement)andaluminiumpowder.Whenthe

  • aluminiumpowderisaddedtoslurryoflime,hydrogenisproducedintheformofbubbles.Thickslurryismadewithlime/cementalongwithaggregates.Aluminiumpowderisaddedinthefinalstageofmixing.Themixispouredintomoulds.Themouldsareautoclavedwhichimpartsstrength.AACisproducedusingnoaggregatelargerthansand.

    Quartzsand,limeand/orcementandwaterareusedasabindingagent.Aluminiumpowderisusedatarateof0.05%0.08%byvolumeofcement.

    Thehydrogengasfoamsanddoublesthevolumeoftherawmix(creatinggasbubblesupto1/8inchindiameter).Attheendofthefoamingprocess,thehydrogenescapesintotheatmosphereandisreplacedbyair.Dependingonitsdensity,upto80%ofthevolumeofanAACblockisair.AACslowdensityalsoaccountsforitslowstructuralcompressionstrength.Itcancarryloadsupto1,200Psi,approximatelyonlyabout10%ofthecompressivestrengthofregularconcrete.

    AACmaterialcanbecoatedwithastuccocompoundorplasteragainsttheelements.SidingmaterialssuchasbrickorvinylsidingcanalsobeusedtocovertheoutsideofAACmaterials.

    EXPERIMENTSOFAAC:SincetheautoclavefacilitywasunavailableattheplacewhereIwasworking,Ididnotautoclavemysamplesandthuswasunabletofinditsactualstrength.

    Themixdesignforthefirstsamplewasdecidedbasedonstudies.Thenfurthersamplesweremadebychangingsomeproportionsinthepreviousones.

    Sampleno.1:Inthisthecement/sandratiotakenis1:1.Alsothew/cmratiotakenis0.4.Aluminiumpowderis0.40.5%byweightofcement.

    Cement(OPC):1.08kgSand:1.08kgWater:440gmAluminiumpowder:45gm

  • Themixturewashotjustaftermixingwhichconfirmedthechemicalreactioninthat.Alsohissingsoundwascomingwhichconfirmedtheevolutionofgas.Sincethisisaeratedconcrete,itshouldexpand.Butitdidnot.Thereasonwaslessamountofwatersinceitdidnotformslurryandthereweregapsbetweentheparticlesthroughwhichalltheevolvedgasesescapedoutfromtheconcrete.Thesegasesshouldremainthereonlysothattheconcreteexpandsbutitdidnothappen.

    Soforthenextsample,Iincreasedthew/cmratiotomaketheslurry.Sampleno.2:Withw/cmratio=0.45Cement(OPC):540gmSand:540gmWater:243gmAluminiumpowder:3gm

    Thismixturemadeslurrywhichwaseasilyflowing.Inthisjustafterfillingthecubetheinitialdepthofthetopsurfaceoftheslurrywas11.5cm.Afterjust5minutes,thedepthwas10cmwhichshowedthatitexpandedaswepredicted.

    Weightofthesample:1.14kgVolume:15x15x5cm3

    Density:1013.33kg/m3

    Sampleno.3:Toreducedensityfurther,Idecreasedthequantityofsand.Cement(PPC):1080gmSand:940gmWater:490gmAluminiumpowder:6gm

    Inthissampletheinitialdepthofthetopsurfaceoftheslurrywas6.8cmandjustafter5minutesthedepthwas3cm.

    Weightofthesample:2.02kgVolume:15x15x12cm3

    Density:748.15kg/m3Thiswasfloatinginwater.

    Sampleno.4:InthisnewsampleItriedtousePumiceStonepowderandreducedthequantityofsandinthemixture.InthissampleIhadtousemorequantityofwatersincepumicestoneabsorbswater.Cement(PPC):1080gmSand:840gmPumiceStonePowder:120gmWater:660gmAluminiumpowder:6gm

    Inthissampletheinitialdepthofthetopsurfaceoftheslurrywas8.6cmandthefinaldepthwas4.5cm.

  • Weightofthesample:2.04kgVolumeofthesample:15x15x10.5cm3

    Density:863.49kg/m3

    Sampleno.5:Sampleof2cubes.Cement:16202=3240gmSand:12602=2520gmPumicestonepowder:1802=360gmWater:9252=1850gmAluminiumpowder:92=18gm

  • Sampleno.6:Sampleof2cubes

    Cement:12962=2592gmSand:10082=2016gmPumicestonepowder:1442=288gmWater:7402=1480gmAluminiumpowder:72=14gm

    Heretheinitialdepthoftopsurfaceofboththecubeswas6cmandthefinaldepthwas0cm.

    Weightofeachcube:2.45kgVolumeofeachcube:15x15x15cm3

    Density:725.92kg/m3

  • Soinall,samplenumbers3,4,5and6werethesuccessfulones.Theyallwerefloatinginwater.

    LIGHTWEIGHTCONCRETEUSINGPUMICESTONE:ThewordPumiceisageneraltermusedforarangeofporousmaterialsproducedduringvolcaniceruptions.Pumicestonecanbeweakandporousorstrongandlessporous.Itswaterabsorptionisashighas55%sinceitisahighlyporousmaterial.Themajorreasonbehindusingpumiceasanaggregateisitsmuchlightweightandcomparativelyhighstrength.

    Pumicestone:light,spongy,highlyporouskindoflavawithavitreoustexture.Pumicehashighsilica&alkaliandlowcalcium&magnesiacontent.Itsspongycellulartextureisaresultofthegasesescapingfromhot

  • lava.Itishavinglowstrengthanditisagoodthermalinsulator,soundinsulatorandfireinsulator.

    TESTSONLIGHTWEIGHTCONCRETEUSINGPUMICESTONEASALIGHTWEIGHTAGGREGATE:Forthisproject,wegotpumicestoneasbigas50mmsize.Sowecrushedittothesizelessthan20mm.Themixdesignforthefirstsamplewasdecidedbasedonstudies.Thenfurthersamplesweremadebychangingsomeproportionsinthepreviousones.

    Sampleno.1:1cubeCement:1.18kgSand:2.63kgPumice:(>10mm):590gm(4.7510mm):910gm(10mm):600gm(4.7510mm):430gm(

  • TheadmixtureusedwasSikaViscocrete5001.Thismadewaterreleasefromcementparticles.

    Afteropeningitwefoundthatitsfinishwasnotgood.Someareasweresmoothandsomewerenot.Itsreasoncameouttobethelargerparticlesofpumicestone.SonexttimeIdidnotuseparticlesbiggerthan10mm.

    Sampleno.3:for3cubesusingaggregateslessthan10mm.Cement:3540gmSand:1800gmPumice(smallerthan10mm):4100gmWater:3400gmAdmixture:21gm

    Thesecubeshadlowdensityandalsosmoothsurface.

    7dayscubetesting:

    S.no,Weightofcube(Kg),Density(Kg/m3),Load(kN)Strength(MPa)1,4.2,1244.44,163.0,7.242,4.4,1303.70,148.4,6.60

    Sampleno.4:Samplefor2cubes.Cement:3540gmSand:2100gmPumice:(4.7510mm):2180gm(

  • architecturalconcrete.Itisagoodinsulatorofheatandsoundandthushasthesameusesasoftheaboveaeratedconcrete.

    REFERENCES1)AmbujaKnowledgeCentreLibrary.AmbujaCementsLtd.2)SamuelGreen,NicholasBrookeandLenMcSaveney.Pumiceaggregateforstructurallightweightandinternallycuredconcretes3)Keertana.B,SiniSaraManiandM.Thenmozhi.Utilizationofecosandandflyashinaeratedconcreteforarichestmixdesign4)HjhKamsiahMohd.Ismail,MohamadShazliFathiandNorpadzlihatunbteManaf.Studyoflightweightconcretebehavior5)HandbookonaeratedconcreteproductsbyPTYLtd6)GiuseppeCampioneandLidiaLaMendola.Behaviorincompressionoflightweightfibrereinforcedconcreteconfinedwithtransversesteelreinforcement(2002)

    ACKOWLEDGEMENTI,DhawalDesai,2ndyearundergraduatestudentofCivilEngineeringdepartment,IndianInstituteofTechnologyBombay,gratefullyacknowledgethesupportandlabfacilityprovidedbyM/sAmbujaCementsLtd.Mumbai,tocarryoutthisprojectworkonLightweightConcreteduringmyinternshipinDec,2011wintervacation.

    Weatengineeringcivil.comarethankfultoErDhawalDesaiforsubmittinghispaperonDevelopmentOfLightWeightConcretetous.Wearehopefulthiswillbeofgreatusetoallthosewhowishtoknowmoreaboutthistopic.


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