Early&Age&Activation&of&SCMs&as&Influenced&by&Alkali& Content&of&Cement&& & & A&thesis&submitted&in&conformity&with&the& requirements&

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1 Early&Age&Activation&of&SCMs&as&Influenced&by&Alkali& Content&of&Cement&& & & A&thesis&submitted&in&conformity&with&the& requirements& for&the&degree&of&master&of&applied&science& Department&of&Civil&Engineering& University&of&Toronto& & & by& & & & Mona&Qouqa& & & & & & & & & &Copyright&by&Mona&Qouqa&2015& & &

2 ii Early&Age&Activation&of&SCMs&as&Influenced&by&Alkali&Content&of&Cement& & & Master&of&Applied&Science& Department&of&Civil&Engineering& University&of&Toronto& Mona&Qouqa& Year&of&Convocation&2015& & Abstract& & AlotofresearchhasbeendoneontheactivationofSCMsinorderto guaranteemaximumperformanceofconcretewhetherthroughdurabilityor strength,especiallyatearlyage.theuseofscmsalongwithlow?alkali cementsmightbesuggestedasanapproachtoensureoptimalconcrete conditionsagainstextremedeteriorationmechanismssuchasalkali aggregatereactions.theissuewiththatisitisthoughtthatthescmsmaybe betteractivatedbyhighalkalicontentcements.thisprojectinvestigates otherdriversforactivation,mainlythecontentofalite.fromthetestresults itisconcludedthatalthoughhighalkalicementcontentwithaveragealite contentsampleshadhighstrength,sodidthelowestalkalicementwiththe highestalitecontent.

3 iii Table&of&Contents& Abstract&...&ii Table&of&Contents&...&iii List&of&Figures&...&v List&of&Tables&...&vii Introduction&...&1 Chapter&1&...&3 Literature&Review&...&3 1.1#Fly#Ash#...#3 1.2#Granulated#Blast#Furnace#Slag#...#5 1.3 Methods#of#activation#...#6 1.4#Data#collected#...#6 Chapter&2&...&9 Experimental&Program&...&9 2.1#Materials#...# PortlandCement Water Aggregates Fineaggregates CoarseAggregates(onlyforconcretemixtures) Admixtures SCMs #Mixing#and#Casting#Procedures#...# MortarCubes Calorimetrytests PoreSqueezing ConcreteMixes #Curing#...# Mortarcubes ConcreteMixtures #Specimen#Testing#...# Calorimeter PoreSqueezing ElectricalResistivity Compressivetesting...16 Chapter&3:&...&17 Results&and&Discussion&...&17 3.1#Mortar#Cubes#Results#...# LafargeSlag(S) HolcimSlag(S2) FlyAsh(F) #Concrete#Mixtures#...#25

4 iv 3.3##Calorimetry#...# FlyAsh HolcimSlag LafargeSlag #Pore#solution#Analysis#...# Flyash HolcimSlag Mortar#Cube#specimens#with#different#curing#solutions#...#31 Chapter&4&...&32 Conclusions&and&Recommendations&...&32 4.1#Conclusions#...#32 4.2#Recommendations#...#32 References&...&33 Appendix&A&...&37 Data&collected&From&the&Literature&...&37 Appendix&B&...&47 Mortar&Cube&Test&Results&...&47 Appendix&C&...&62 Concrete&Mixtures&Test&Results&...&62 Appendix&D&...&65 Pore&Squeezing&Data&...&65

5 v List&of&Figures& Figure1:Strengthratiosat1,3,7daystostrengthat28daysversuscementalkali content...7 Figure2:Strengthsat1,3,7daysasarationtostrengthat28daysversusflyash alkalicontentfromliterature...8 Figure3:Mixingofmortar...12 Figure4:Stainlesssteelcubemolds...12 Figure5:Poresqueezingapparatus...15 Figure6:Compressivestrengthdevelopmentfordifferentalkalicementsand50% LafargeSlag(S)...18 Figure7:Strengthsforthethreehighestearlyagestrengthforcementswith50% Lafargeslag...18 Figure8:Resistivitydevelopmentfordifferentalkalicementswith50%Lafarge slag...19 Figure9:Compressivestrengthdevelopmentforcementwith50%HolcimSlag(S2)...20 Figure10:Strengthswithstandarddeviationerrorbarsforthethreehighestearly agestrengthdevelopmentcementsforcementsblendedwith50%holcimslag...20 Figure11:Resistivitydevelopmentformixeswith50%Holcimslag...21 Figure12:Strengthdevelopmentwithalkalicontentatdifferentagesforallcements (bothslags)...21 Figure13:Strengthdevelopmentforcementshavingdifferentalitecontentat differentagesforallcements(bothslags)...22 Figure14:Strengthdevelopmentforallcementswith25%flyashreplacement...23 Figure15:Standarddeviationerrorbarsforthefourhighestearlyagestrength developmentcementsforcementswith25%flyash...23 Figure16:Strengthdevelopmentforcementswithdifferentalkalicontentat differentagesforallcementswithflyashreplacement...24 Figure17:Strengthdevelopmentwithalitecontentatdifferentagesforallcements withflyashreplacement...24 Figure18:StrengthDevelopmentovertimefor100%cementconcretemix...25 Figure19:StrengthDevelopmentfor50%Holcimslagconcretemix...25 Figure20:Powerchangewithtimeforflyashspecimens...26 Figure21:Energychangewithtimeforflyashspecimens...26 Figure22:PowerchangewithtimeforHolcimslagspecimens...27 Figure23:EnergychangewithtimeforHolcimslagspecimens...27 Figure24:PowerchangewithtimeforLafargeslagspecimens...28 Figure25:EnergychangewithtimeforLafargeslagspecimens...29 Figure26:Hydroxylconcentrationsof25%flyashconcretestohydroxyl concentrationofportlandcementcontrolforeachcementused...29 Figure27:Hydroxylionconcentrationof50%slagmixturestohydroxyl concentrationofportlandcementforeachcementalkalicontentused...30

6 vi Figure28:StrengthdevelopmentforSlagandcontrolmixeswithdifferentcuring solutions...31

7 List&of&Tables& Table1:Chemicalcompositionoftheeightcementsused...9 Table2:AggregateProperties...10 Table3:PropertiesofSCMsused...11 Table4:Mortarmixdesignfor6cubes...11 Table5:Concretemixturedesigns...13 Table6:Freshconcretemixtureproperties...14 vii

8 1 Introduction& Supplementarycementitousmaterials(SCM)areby?productmaterialsofindustrial processes.theyoftenhavelittleornocementitiousvalue,butwiththeadditionof cement,theyreactchemicallywithcalciumhydroxidefromthecement?water reactionatroomtemperaturetoformcompoundssimilarinstructuretothemain buildingcomponentsofconcrete. SCMshavebeenusedaspartialreplacementforcementinconcreteproductionin NorthAmericasincethe1970s.Notonlydotheyimprovestrength,durabilityand workabilityofconcretewithouthinderingitsperformancecharacteristics,butmay alsohelpreducethecostofconcreteandreducepollution(debrito2013). ThetwoSCMsfocusedoninthisprojectwereflyashandslag.Theybothare structurallymadeofglassymaterial.inordertochemicallyreactinconcrete, producingthedesiredmechanicalproperties,theglassystructureincreasestheir potentialfordissolutioninanalkalineenvironmentforthesubsequentproduction ofcalciumsilicatehydrates(diamond1981). Activationoftheflyashandslag,andstrengthdevelopment,areconsideredby researcherstobemainlybasedonthealkalinityoftheporesolutioninconcrete, whichisinfluencedbythealkalicontentofthecementsused(nixonandpage1987, Hobbs1981).Therefore,theuseoflow?alkalicementsinaconcretemixture,often usedtohelppreventdeteriorationduetoalkali?aggregatereaction,mightaffectthe activationoftheaforementionedscms. Thisprojectfocusedondeterminingwhetherthecementalkalicontentisthesole driverbehindtheactivationofscmsorifachangeinthemineralogicalcomposition (aliteandbelite)ofcementhasaneffectontheactivationaswell.withfactorslike, curingtemperatureconditionsandfinenessofcementkeptconstant,theproject wasundertakenintwophases;phaseoneinvolvedcastingofmortarcubesand PhaseTwoinvolvedcastingofconcrete.Moreover,calorimetryandporesolution extractionwerealsodonetoprovideinsightontheeffectofcementpropertieson heatofhydrationandalkalicontentofporesolution.

9 2 Eightdifferentcementswereused;fivefromdifferentcementplantsandthree blendsoftheotherfivecreatingarangeofdifferentcementalkalicontentsaswell asaliteandbelitecompositions.eachmixturewasusedwith25%flyash replacementofcementor50%replacementofcementwithholcimandlafarge slags.

10 3 Chapter&1& Literature&Review& Alkalisinconcretemainlyderivefromthecementiousmaterialsused,namely cementsandpozzolans.initially,ascementismixedwithwater,calciumandalkali sulfatesdissolveandreactwithtricalciumaluminate.solublealkalisalsogointo solution,causinganincreaseinthehydroxylconcentrationinthesystem,andthe poresolutionbecomessaturatedwithrespecttocalciumhydroxide.afterafew hours,thehydrationreactionsprogresscausingsulphatestodecreasein concentrationandafurtherincreaseinhydroxylsoccurs.afteroneday,calciumis reducedtoverylowamountsandtheresultantporesolutionisconstitutedmainly ofsodiumandpotassiumhydroxides(diamond1981). 1.1&Fly&Ash& FlyAshisamanmadesupplementarycementitiousmaterialwithpozzolanic propertiesproducedfromcoalcombustion.itisusedasapartialreplacementfor portlandcementcontentsinconcrete.asperastmc618,pozzolansaredefinedas: siliceous,orsiliceousandaluminousmaterials,whichinthemselvesposseslittleor nocementitiousvaluebutwill,infinelydividedformandinthepresenceof moisture,chemicallyreactwithcalciumhydroxideatordinarytemperaturestoform compoundspossessingcementitiousproperties. FlyAshismainlyconstitutedofveryfineglassyspherical?likeparticlesthatarefiner thanportlandcements.chemically,itismadeofmainlysilica(sio2),alumina (Al2O3),ironoxides(Fe2O3),andcalciumoxides(CaO)(JoshiandLohtia1997). Therecognitionofthispozzolanicmaterialdatesasfaras1914,withthefirst researchstudyreportedofitsuseinconcreteconductedbydavisandhisassociates attheuniversityofcaliforniain1937.datafromliteratureonflyashusein concrete,between1934and1959,wascollectedandcompiledbyabdunnurina

11 4 publicationin1961.severalpublicationsbyknownresearcherswereconducted afterthatsuchassynder1962,joshi1979,berryandmalhotra1986. Dependingontheorigin,chemicalandmineralogicalcompositionofflyash,itcanbe classifiedintotwomainclasses:low?calciumflyashesandhigh?calciumones.low? calciumflyashes,orastmc618classfaretypicallyusedforasrmitigation (Diamond1981). Theuseofflyashinconcreteproducesspecialpropertiesrequiredforstrengthand durabilityofconcreteforfieldapplications.generallyflyash,irrespectiveofits composition,reducesthewaterdemandofconcreteprovidingabetterresistanceto fluidmovementanddiffusionofharshions(gillot1975). Understandardcuringconditions,thepozzolanicreactionofthelowcalciumflyash issloweratearlyagesthanportlandcements.itisbelievedthatafteraperiodof weeks,thattheglassyparticlesarebrokendownbythealkalicontentofthepore solution,thisallowsthemtoreactwiththecalciumhydroxidesinthesystemfrom thecementhydration.thereactionproducesacalciumalkalisilicatehydratethatis verysimilarinstructuretothecalciumsilicatehydrateformedbyhydration reactionofcement.itisalsoassumedthattheslowerstrengthdevelopmentatearly agesmightbeduetothefactthatlesscementisavailableintheconcretewiththe replacement(diamond1981). Researcherssuggestthatflyashimprovethedurabilityofconcretebyseveralways: 1. Dilutionofcementalkalisbythefactthattheflyashisreplacing paretofthecementused(onlyincaseofcementalkali>flyash alkali),improvingdurabilityagainstalkali?aggregatereactions (Nixonetal1986) 2. Reductionoftheconcretepermeabilityanddiffusivitybythe productionofmorecsh(thepozzolanicreaction),therefore protectingagainstexternalaggressiveagents(massazza1998).

12 5 3. Theflyashreactswiththealkalispresentintheporesolutionto enhanceitsactivation.thisreducesthetotalalkalicontentinthe systemtopreventaar(hobbs1981,nixonandpage1987). Pointsoneandthreeassumethatalkaliintheporesolutionisthemainactivator behindtheflyash. AstudyconductedbyNixonandPage(1987)statesthatthreemainfactorsaffect thehydroxylionconcentrationintheporesolution:thealkalicontentofthecement, thereplacementamountandalkalicontentoftheflyash.theirresultsshowa decreaseinthehydroxylionconcentrationswithincreasinglevelofcement replacementwithflyash,albeitthecorrelationisnon?linear. Hobbs(1981)studiedtheeffectofusingclassFflyashinimprovingthedurabilityof concreteagainstaar.theresultshaveshownthatsampleswitha30?40%flyash replacementweremoredurablethanoneswith100%portlandcement.moreover, itwasconcludedthattheflyashneededalkalicontenttoreact. 1.2&Granulated&Blast&Furnace&Slag& Granulatedblastfurnaceslagisaproductofpigironproductionandisusedasa cementitiousmaterialintheconcreteindustry. ItwasfirstusedasanSCMbyEmilLangenin1868inGermany(Papadakisand Venuat1966). ThecompositionmainlyconstitutesofSiO2,Al2O3,CaO,andFe2O3.Unlikeandfly ash,slagshowshydraulicpropertieswhenusedwithcementinconcrete.slag s glassystructurereactswith,calciumsulphates,andalkalisinthesystem. Whenmixedwithwater,theslagparticlesreleasecalciumionsintosolution,andan impermeablelayerformsaroundtheslagparticle.uponthehydrationofcement andtheproductionofcalciumhydroxide,theaforementionedlayerisdestroyed. Theliberatedslagparticlesthenproceedtoreactwithcalciumsulphatesandalkalis toproducecalciumsilicatehydrate.similartoslag,theearlyagestrength developmentofslagisslowerthanthatofportlandcement(tanakaetal1983).

13 6 AstudyconductedbyDuchesneandBerube(2001)statedthattheglassystructures oftheflyashandslagusedinaconcretemixisbrokendownandactivatedfasterby thesolublealkalispresentinsolutionfromcement.theirfindingsshowthatthe alkalisareboundtothecshformedfromtheaddedscms. 1.3 &Methods&of&activation&& Othermethodsofactivationmentionedinstudieswere: 1. Mechanicalactivation(grindingofSCM) 2. Chemicalactivation 3. Thermalactivation Theactivationofflyashandslagwasinvestigatedwithadditionofsodium hydroxidesolution(naoh)tothesystem.witheverythingelsekeptconstant,the mainparametersvariedwere:curingtemperaturesandnaohconcentrations. Resultsshowedalinearcorrelationbetweenstrengthdevelopment,asignof activation,andnaohconcentrations.theincreaseincuringtemperature,however, improvedstrengthforthefirstfewdaysofhydration,buthadaworseeffectonlong termstrength(puertaselat2000). Otherstudies(Arjunan2001)examinedtheactivationofflyashwithacombined chemical/mechanicalmechanismfortheactivationprocess.severalcompounds wereusedalongwithflyashofdifferentfineness.whenusedtogether,theeffectsof chemicalactivatorsincludingsodiumhydroxide,sodiumcarbonate,andcalcium hydroxideactivationwereenhanced.withanychemicalactivatorused,finerashes wereactivatedmorethancoarserones. 1.4&Data&collected&& Inthissection,datafromtheliteraturewascombinedinagraphicalrepresentation inordertotryandfindacorrelationbetweencementalkalicontentandstrength development(asanindicatorofactivation)offlyash.initially,thecollecteddata includedarangeofflyashreplacements,curingconditionsandtemperatures.the informationwasthennarroweddowntocertainfactorssuchas,standardroom

14 7 temperatureconditions,similarcuringconditionstothoseusedthisproject,water? to?cementratiosnothigherthan0.55,andflyashreplacementlevelsbetween25 and30%.theselectedinformationwas: 1. Sodiumandpotassiumlevelsincement(%). 2. Cementcontent(kg/m 3 ). 3. Sodiumandpotassiumlevelsinflyash(%). 4. Flyashcontent(kg/m 3 ). 5. Watertocementratio. 6. Curingcondition. 7. Curingtemperature. 8. Strengthat1,3,7and28days(MPa). TwographswereplottedandareshowninFigure1andFigure2.Thecomplete tablewiththereferencesisprovidedinappendixa fc'/fc'&28days&(mpa)& day 3day 7day Cement&Alkali&Content&(%)& Figure&1:&&Strength&ratios&at&1,&3&,&&&7&days&to&strength&at&28&days&versus&cement&alkali&content&

15 fc'/fc'&28days&(mpa)& day 3day 7day FA&Alkali&Content&(%)& Figure&2:&Strengths&at&1,&3&,7&days&as&a&ratio&to&strength&at&28&days&versus&fly&ash&alkali&content&from& literature& & Strengthvalueswereplottedasstrengthateachtestingdaytostrengthat28days. Asexhibitedinbothfigures,nodistinctcorrelationwasdeduced.

16 9 Chapter&2& Experimental&Program& Understanding+the+activation+mechanisms+of+SCMs+in+a+concrete+matrix+is+imperative+for+ evaluating+the+adequacy+of+a+concrete+mix+and+the+materials+of+which+it+is+composed.+ The+following+program+investigates+the+activation+of+the+SCMs+through+the+mechanisms+ described+in+chapter+1.+the+methods+and+materials+used+are+of+high+importance+in+ achieving+good+and+reproducible+results.+ 2.1&Materials& This+section+provides+details+of+the+materials+used &Portland&Cement& The+portland+cements+were+provided+by+Lafarge s+whitehall,+alpena,+and+ravena+plants,+ as+well+as+st+marys+bowmanville,+and+holcim+mississauga+plants.+the+cements+selected+ meet+astm+type+i+specifications+and+canadian+specification+can/csaka3001general+ use.+a+vkblender+was+used+at+35+rpm+to+blend+additional+three+cements+from+the+other+ five+plantkprovided+cements+to+form+a+range+of+alkali+contents+for+testing+purposes.+the+ chemical+compositions+for+all+cements+are+shown+in+table+1.+ Table&1:&Chemical&composition&of&the&eight&cements&used& Low& Alkali Whitehall Medium& Alkali St&Marys High Low+HighMed+low Med+& High Alkali&Content& (%) C 3S&(%) C 2S&(%) C 3A&(%)

17 10 C 4AF&(%) &Water& The+water+used+in+the+concrete+mixtures+consisted+of+potable+tap+water &Aggregates& Fine+aggregates++ ASTM+C778+graded+Ottawa+sand+was+used+for+all+mortar+mixtures.+For+concrete,+natural+ glacial+sand+was+used.++the+physical+properties+are+provided+in+table Coarse+Aggregates+(only+for+concrete+mixtures)+ As+for+the+coarse+aggregates,+20mm+crushed+limestone+was+used.+The+physical+ properties+can+be+viewed+in+table2.+ Table&2:&Aggregate&Properties& Aggregate' Type' Relative'Density' Absorption'(%)' Fine+ Silica Coarse+ Limestone &Admixtures&& WaterKreducing+admixtures+were+used+in+the+concrete+mixtures+in+order+to+achieve+the+ required+slump.+a+superplasticizer+was+also+used+to+increase+the+fluidity+to+obtain+ suffient+slump &SCMs& Two+supplementary+cementing+materials+were+used:+Fly+ash+(Lafarge,+Stoney+Creek+)+and+

18 11 Slag+(from+both+Holcim,+Mississauga+and+Lafarge,+Stoney+Creek).+The+Blaine+fineness+and+ alkali+contents+are+provided+in+table+3.+ Table&3:&Properties&of&SCMs&used& Holcim& Slag&& Lafarge& Slag&& Fly&Ash& Surface&Area& Blaine&(m²/kg)& Alkali&Content& (%)& & & 2.2&Mixing&and&Casting&Procedures& &Mortar&Cubes& Mortar+mixtures+were+designed+as+per+C109/C109M+.+A+water+to+cement+ratio+of was+used+for+the+mortar+cubes.++a+total+of+32+mixes+were+cast+which+were+a+combination+ of+the+8+cements:+8+with+100%+cement+(control),+8+with+25%+fly+ash,+8+with+50%+holcim+ slag,+and+8+with+50%+lafarge+slag.+the+mix+design+is+shown+in+table+4.+ Table&4:&Mortar&mix&design&for&6&cubes& Material& Quantity&(g)& CementitousMaterial Sand 1375 Water 242 A+mechanical+mixer+with+a+stainless+steel+bowl+with+a+stainless+steel+paddle+was+used+as+ per+astm+c305+(figure3).++after+mixing,+the+mortar+is+placed+in+stainless+steel+50mm+ cube+molds+(figure4)+and+covered+with+plastic+wrap+and+left+to+set+for+24+hours+in+a+ plastic+container+at+standard+conditionsofroomtemperatureat23.0±3.0 Cand

19 12 55%relativehumidity+before+deKmolding Figure&3:&Mixing&of&mortar Figure&4:&Stainless&steel&cube&molds& 2.2.2&Calorimetry&tests& Sample+made+for+the+calorimetry+tests+were+designed+as+the+mortar+cubes+in+the+ previous+section.+samples+of+100g+of+mortar+are+placed+in+plastic+vials+and+inserted+in+ the+vial+holders+in+the+calorimeter+for+testing &Pore&Squeezing&& Mortar+samples+for+the+pore+squeezing+tests+were+also+the+same+as+the+mortar+cubes+in+ the+preceding+section.+samples+were+cast+in+50mm+in+diameter+by+100mm+long+cylinders+ and+sealed+and+stored+under+standard+conditions+until+testing.++

20 &Concrete&Mixtures& Only+six+concrete+mixtures+with+three+different+cements+where+selected+and+prepared+ for+this+experimental+investigation.+the+three+cements+included+low,+medium+and+high+ cement+alkali+contents.+a+0.43+water+to+cementitious+materials+ratio+was+selected+for+all+ mixtures.+the+individual+mixture+designs+are+detailed+in+table+5.+ Table&5:&Concrete&mixture&designs& Mixture& ID& 0.803:PC& 0.573:PC& 1.07:PC& 0.803:50S& 0.573:50S& 1.07:50S& W/CM& Batch& Volume&(m 3 )& Materials& Mass(kg/m 3 ) Cement& Slag&??? Water& Fine& Aggregate& Coarse& Aggregate& Water& Reducer& ml/batch& Supere Plasticizer& ml/&batch& ml 18ml 15ml 20ml 15ml 15ml 10ml 10ml 10ml 20ml 15ml 5ml Aggregate+preparation+and+mixing+procedures+were+carried+out+as+per+the+ASTM+C172+ and+astm+c192+standards.+fresh+concrete+properties+were+measured+(table6).+ Concretes+were+cast+into+100+x+200+mm+(4+x+8+in)+cylindrical+specimens.++

21 14 Table&6:&Fresh&concrete&mixture&properties& Mixture&ID& 0.803:PC& 0.573:PC& 1.07:PC& 0.803:50S& 0.573:50S& 1.07:50S& Slump&& (ASTM&C143)& Percent&Air&Content& (ASTM&C173)& 100mm 105mm 100mm 110mm 110mm 105mm 3% 2.7% 3% 3% 2.9% 2.9% Temperature&& (ASTM&C1064)& 25.2 O C 25.5 O C 25.1 O C 25.6 O C 25.5 O C 25.6 O C Unit&Weight&& (ASTM&C138)& kg/m 3 kg/m 3 kg/m 3 kg/m 3 kg/m 3 kg/m &Curing& 2.3.1&Mortar&cubes&& Mortar+cubes+were+cured+in+limewater+until+the+required+testing+ages+of+1,+3,+7,+and+28+ days.+after+demolding,+samples+tested+at+one+day+were+immersed+in+limewater+for+20+ min+before+testing.+samples+are+removed+from+their+curing+basin+for+testing+at+the+same+ time+they+were+dekmolded+and+immersed+at+to+ensure+accuracy+and+reproducibility+of+ results.++ For+experimental+purposes,+three+mixtures+were+made+with+the+1.070%+alkali+content+ cement+and+were+immersed+in+three+other+curing+solutions:+ 1. Tap+water %+Alkali+content+solution %+Alkali+content+solution+ & &

22 &Concrete&Mixtures& All+concrete+samples+are+cured+in+their+plastic+sealed+molds+for+24+hours+before+they+are+ immersed+in+limewater+solutions+at+standardized+conditions+until+day+of+testing.+day+one+ samples+are+immersed+in+solution+for+20+min+before+testing &Specimen&Testing& Tests+included+compressive+strength+development+over+time,+electrical+resistivity,+ isothermal+calorimerty,+and+alkali+content+through+pore+squeezing &Calorimeter& As+per+the+ASTM+C1679,+Standard'Practice'for'Measuring'Hydration'Kinetics'of'Hydraulic' Cementitious'Mixtures'Using'Isothermal'Calorimeter,+the+heat+released+by+the+hydration+ of+cementitious+materials+was+measured+over+a+period+of+seven+days &Pore&Squeezing&& Pore+squeezing+was+done+at+1,+3,+7,+and+28+days+for+the+Holcim+slag,+fly+ash+and+control+ mixtures+for+three+different+cements+with+different+alkali+contents+(1.070%,+0.803%+and %).+Mortar+cylinders+were+prepared+in+50x100mm+molds+and+sealed+until+the+day+ of+testing.+fluid+is+extracted+out+of+the+hardened+samples+by+high+pressure+and+is+tested+ for+hydroxyl,+potassium+and+sodium+ion+concentrations.+figure+5+shows+a+schematic+of+ the+pore+squeezing+apparatus+(23).++ Figure&5:&Pore&squeezing&apparatus&'

23 &Electrical&Resistivity& Electrical+resistivity+was+measured+and+calculated+as+per+ASTM+C1760,+Standard'Test' Method'for'Bulk'Electrical'Conductivity'of'Hardened'Concrete &Compressive&testing& The+compressive+strength+testing+of+concrete+was+done+as+per+ASTM+C39,+Standard'Test' Method'for'Compressive'Strength'of'Cylindrical'Concrete'Specimens.+As+for+the+mortar+ cube+samples,+the+procedure+followed+was+the+astm+c109/c109m,+standard'test' Method'for'Compressive'Strength'of'Hydraulic'Cement'Mortars

24 17 Chapter&3& + Results&and&Discussion& 3.1&Mortar&Cubes&Results& Results+of+strength+and+resistivity+development+graphs+are+shown+in+this+section.+ Strength+development+was+plotted+against+time,+alkali+content+of+cement,+and+cement+ alite+content.+resistivity+was+monitored+over+time.++++ The+mix+codes+used+in+the+graphs+below+show+the+alkali+content+with+the+percent+of+ SCM+replacement+(alkali+content:+percent+replacement) &Lafarge&Slag&(S)& Figure6+shows+that+the+highest+strength+development+at+1,+3,+and+7+days,+occurred+for+ the+highest+alkali+content+cement:+1.003%,+followed+closely+by+the+0.9%+and+the+0.543%+ one+both+at+almost+the+same+values.+chemical+analysis+in+table1+in+chapter+2,+also+ shows+that+the+0.54%+alkali+cement+also+had+the+highest+level+of+alite,+that+may+also+be+a+ cause+for+the+activation.+figure7+displays+strengths+for+the+three+cements+with+ standard+deviation+error+bars.+1,+3,+and+28+day+strengths+for+all+cements+have+very+small+ standard+deviation+values:+the+1.00%+and+0.54+%+cements+showed+standard+deviations+ of+2+mpa+at+7+days.+++ Resistivity+values+over+time+are+shown+in+Figure8.+It+is+observed+that+the+1.00%+and+ 0.9%+alkali+cements+had+the+highest+resistivity+values.++ +

25 18 60 Compressive&Strength&(MPa)& Time&(Days)& 0.9:50S 1.003:50S 0.543:50S 0.603:50S 0.573:50S 0.773:50S 0.803:50S 1.07:50S + Figure&6:&Compressive&strength&development&for&different&alkali&cements&and&50%&Lafarge&Slag&(S)& 60 Compressive&Strength&(MPa)& :50S 1.003:50S 0.543:50S Time&(Days)& Figure&7:&Strengths&for&the&three&highest&early&age&strength&for&cements&with&50%&Lafarge&slag&

26 Resistivity&(ohmem)& :50S 0.9:50S 0.543:50S 0.603:50S 0.573:50S 0.773:50S 1.07:50S 0.803:50S Time&(days)& Figure&8:&Resistivity&development&for&different&alkali&cements&with&50%&Lafarge&slag& &Holcim&Slag&(S2)& Results+in+Figure9+are+similar+to+that+for+the+Lafarge+slag+in+the+previous+section+where+ the+highest+early+age+strength+development+occurred+for+the+highest+alkali+content+ cements:+0.9%+and+1.00%,+as+well+as+the+lowest+alkali+content+one:+0.54%.+figure10+ displays+the+three+cements+with+standard+deviation+error+bars.+resistivity+values+over+ time+are+shown+in+figure11.+it+is+observed+that+the+1.00%+and+0.90%+alkali+cements+ show+the+highest+resistivity+values,+followed+closely+by+the+0.54%+one.++

27 20 50 Compressive&Strength&(MPa)& :50S :50S :50S :50S :50S :50S :50S2 1.07:50S Time&(Days)& Figure&9:&Compressive&strength&development&for&cement&with&50%&Holcim&Slag&(S2)& 50 Compressive&Strength&(MPa)& :50S :50S :50S Time&(Days)& Figure&10:&Strengths&with&standard&deviation&error&bars&for&the&three&highest&early&age&strength& development&cements&for&cements&blended&with&50%&holcim&slag&

28 Resistivity&(ohmem)& :50S2 0.9:50S :50S :50S :50S :50S2 1.07:50S :50S Time&(days)& Figure&11:&Resistivity&development&for&mixes&with&50%&Holcim&slag& Compressive&Strength&(Mpa)& S21day S23day S27day S228day S11day S13day S17day Cement&Alkali&Content&(%)& S128day Figure&12:&Strength&development&with&alkali&content&at&different&ages&for&all&cements&(both&slags)'

29 22 + Compressive&Strength&(Mpa)& S21day S23day S27day S228day S11day S23day S17day C3S&(%)& S128day Figure&13:&Strength&development&for&cements&having&different&alite&content&at&different&ages&for&all& cements&(both&slags)& + Figure12+and+Figure13+show+the+strength+development+data+for+different+cement+ alkali+content+and+alite+content+for+mixtures+made+with+both+slags.+the+results+match+ the+ones+mentioned+above+in+the+preceding+two+sections.+moreover,+both+slags+act+ similarly+at+early+ages+while+there+is+some+noise+in+the+data+at+the+28kday+results.++ & 3.1.3&Fly&Ash&(F)& + Results+in+Figure14+show+a+similar+outcome+to+that+of+the+slags+in+the+previous+sections+ where+the+highest+early+age+strength+development+occurred+for+the+highest+alkali+ content+cements:+0.9%+and+1.00%,+as+well+as+the+low+alkali+content+ones:+0.54%+and+ 0.60%.+Figure15+displays+strengths+for+these+four+cements+with+standard+deviation+ error+bars.+++

30 23 Figure16+and+Figure17+both+show+that+the+highest+strength+had+occurred+for+the+ 1.00%,+0.90%+and+0.54%+alkali+cements.+ & 60 Compressive&Strength&(MPa)& :25F 1.003:25F 0.543:25F 0.603:25F 0.773:25F 0.573:25F 0.803:25F :25F Time&(Days)& Figure&14:&Strength&development&for&all&cements&with&25%&fly&ash&replacement& 60 Compressive&Strength&(MPa)& :25F 1.003:25F 0.543:25F 0.603:25F Time&(Days)& Figure&15:&Standard&deviation&error&bars&for&the&four&highest&early&age&strength&development&cements& for&cements&with&25%&fly&ash&

31 Compressive&Strength&(Mpa)& day 3day 7day 28day Alkali&Content&(%)& Figure&16:&Strength&development&&for&cements&with&different&&alkali&content&at&different&ages&for&all& cements&with&fly&ash&replacement& 60 Compressive&Strength&(Mpa)& day 3day 7day 28day C3S&(%)& Figure&17:&Strength&development&with&alite&content&at&different&ages&for&all&cements&with&fly&ash& replacement&

32 25 3.2&Concrete&Mixtures& Thissectionshowstheresultsforthesixconcretemixturesselectedtoverifythat themortarcuberesultsareconsistentwithconcreteresults. Themixesonlyused50%Holcimslagreplacementsfortheconcreteswiththree differentalkalicements. Thethreecementsusedhad1.00%,0.80%and0.57%alkalicontents,chosento coverthealkalicontentrange. Compressive&Strength&(MPa)& Time&(days)& 1.07:PC 0.803:PC 0.573:PC Figure&18:&Strength&Development&over&time&for&100%&cement&concrete&mix& Compressive&Strength&(MPa)& :50S :50S :50S Time&(days)& Figure&19:&Strength&Development&for&50%&Holcim&slag&concrete&mix& &

33 26 3.3&&Calorimetry& Theisothermalcalorimetrytestresultsareshowninfollowingfigures &Fly&Ash& Figure&20:&Power&change&with&time&for&25%&fly&ash&specimens& &Figure&21:&Energy&change&with&time&for&25%&fly&ash&specimens&

34 27 Figure20showsthepowerlevelchangesofthesampleswithtime.Thethree cementsthatproducedhigheststrengthresultsintheprecedingsectiondidnot matchuptothecalorimetryresultsshownhere.mediumalkalicontentcements producedthehighestenergy &Holcim&Slag& Figure&22:&Power&change&with&time&for&50%&Holcim&slag&specimens& Figure&23:&Energy&change&with&time&for&50%&Holcim&slag&specimens&

35 28 Figure22showsthepowergraphfortheHolcimslagwithtime.Theresultsshows thatthehighestthreepeaksbelongtothe0.54%,0.90%and1.00%alkalicontent cements.thelowestalkalicontentcementhastheearliestpeakateighthours followedbythe0.9%and1.00%at14and16hoursrespectively.figure23shows similarresultswiththehighestlevelsofenergyreleasedwereforthe aforementionedcementsfollowedcloselybythe0.80%alkalicontentcement. & 3.3.3&Lafarge&Slag& Figure&24:&Power&change&with&time&for&50%&Lafarge&slag&specimens& Figure24showsthatthe0.54%alkalicementhadtheearliestpeak,butthe1.00% alkalicementhadthehighestpeak.figure25showsthatthehighestenergylevel belongstothe0.80%alkalicementfollowedcloselybythe0.54%one,withthe 1.00%alkalicementbeingthelowest.

36 29 Figure&25:&Energy&change&with&time&for&50%&Lafarge&slag&specimens& 3.4&Pore&solution&Analysis& Inthissectionthesamethreecementsselectedfortheconcretemixingwere usedforporesolutionanalysis &Fly&ash& [OHe]&of&SCM&/&[OHe]&of&PC& :25F 0.773:25F 0.573:25F Cement&Used& Figure&26:&Hydroxyl&concentrationsof&25%&fly&ash&concretes&to&hydroxyl&concentration&of&portland& cement&control&for&each&cement&used&

37 30 Figure26showsthechangeinhydroxylionconcentrationswithtimeandwith cementalkalicontentdecreasefor25%flyashspecimens.withtime,thehydroxyl leveldropsforeachmix.somemixesdonothave28daymaterialbecausenofluid hasbeenabletobeextractedfromthespecimen. Moreover,asexpected,asthecementalkalicontentdecreasessodoesthelevelof hydroxylionconcentration.fromfigure16,itisalsoshownthatthestrength decreaseswithalkalicontentofcementforthosethreecementsandthereforeso doesthehydroxyl. & 3.4.2&Holcim&Slag& [OHe]&of&SCM&/&[OHe]&of&PC& :50S 0.773:50S 0.573:50S Cement&Used& Figure&27:&Hydroxyl&ion&concentration&of&50%&slag&mixtures&to&hydroxyl&ion&concentration&of&Portland& cement&for&each&cement&alkali&content&used& Figure27showsthatthelevelsofhydroxylionsdecreasewithtimeforeach mixture.thevaluesdonotchangealotbetweenthemixturesforages1and3,but showadecreaseofhydroxylwithdecreaseofalkalicontentfor7dayage.similarto themixtureswithflyash,figure12showsthatthesethreecementsexhibited reducedstrengthvalueswithincreasesincementalkalicontent &

38 &Mortar&Cube&specimens&with&different&curing&solutions& Inthissection,asinglecementwasselectedandtestedwithmultiplecuring solutions:limewater,tapwater,0.3%na2oalkaliequivalentand0.6%na2oalkali equivalenttocheckifthecuringsolutionaffectstheactivation.the1.07%alkali contentcementwasused,andtwomixeswerecast,onewith50%slagandtheother 100%Portlandcement. Figure&28:&Strength&development&for&50%&Slag&and&control&mixes&with&different&curing&solutions& Figure28showsthatthefastestactivationoccurredforthesamplescuringin limewateraswellasthe0.6%alkalisolution.

39 32 Chapter&4& Conclusions&and&Recommendations&& 4.1&Conclusions& Fromtheexperimentalresultsitisconcludedthat: 1. CementalkalicontentisanactivatorforSCMs.AstheresultsinChapter3 show,thevaluesforstrengthwerethehighestforthehighestalkalicontent cement(1.07%).thisprovesthatalkalisarebeneficialtoenablescmsto startreactingandformingcalciumsilicatehydrate?likeconstituents. 2. Highalitecontentinthecementhadalsobeenproventobeadriverforthe activationofscmsevenwithcementshavinglowalkalicontents.from Chapter3,itwasobservedthatstrengthvaluesofthelowestalkali/highest C3Scontentcement(0.543%)wereveryclosetothoseobtainedwiththehigh alkalicements(1.07%and0.9%).calorimetryvaluesalsoshowthatthere wasoftenanearlyhighspikeinpowervaluesforhighalitecement. 3. Curinginasolutionsimulatinghighalkalicementhelpspreventleachingof alkalisfromtheporesolutionintheconcrete,andresultsinincreased strength.fromthelastsectioninchapter3,itwasshownthatstrength developmentforearlyages(1,3,and7days)ofmortarcubeswasthehighest formixturesstoredinthe0.6%na2oalkaliequivalentcuringsolution.this provesthatthealkaliswereabsorbedintotheporewaterandusedin activatedthescmfaster. 4.2&Recommendations& Recommendationsforfurtherresearchincludeevaluationofcementswithawider rangeofalkaliandalitecontents.moreover,otherfactorsthatwerekeptconstant couldbeinvestigatedsuchascuringtemperaturesandadditionofalkaliactivators tothesystemduringthemixingprocess.

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44 37 Appendix(A( Data(collected(From(the(Literature( Reference(( K2O( of( PC((( (%)( Na2O( of(pc(((( (%)( Na2O( equ( of(pc( (%)( Amoun t(of(pc( (kg/m3 )( Amount(of(( Fly(Ash( (kg/m3)( Curing( condition( w/c( TempeI rature( ( o C)( Na2O( of(fa(((( (%)( K2O(of( FA((( (%)( Na2O( equ(of( Fly(Ash( (%)( F'c(at( 1d((((( (Mpa)( F'c(at( 3d( (Mpa )( F'c(at( 7d( (Mpa )( F'c(( at( 28d( (Mpa )( %Fly( Ash( f'c1/f' c28( f'c3/f'c 28( f'c7/f'c 28( Thomas(et(al( 96( Prisms demoulded at24hours andthen curedat20 degrees < < < < < < (( Prisms demoldedat 24hours andthen curedat20 degrees < < < < < < Poon(et(al( 2000( < < Water immersed < < 0.14 < < < < 0.72 < < Water immersed < < 0.14 < < < < 0.70 ( (

45 38 ( Water immersed < < < < 0.77 (( Water immersed < < < < 0.88 Ramezanianpo Iur(and( Malhotra(1995( moist (( moist (( roomtemp after demoulding (( roomtemp after demoulding Thomas(et(al( 1989( ( waterstored < < <

46 39 ( waterstored (( curedfor1 daythenair stored, rh= < < < (( curedfor1 daythenair stored, rh= (( curedfor2 daysthenair stored, rh= < < (( curedfor3 daysthenair stored, rh= < < (( curedfor7 daysthenair stored, rh= < < < < 0.69 Plante(and( Bilodeau(1989( wetburlap atroom tempforday 1thenmoist room100% rh < < 0.79

47 40 (( wetburlap atroom tempforday 1thenmoist room100% rh < < 0.71 Gebler(and( Klieger(1986( Moistinfog room (( Moistinfog room (( Moistinfog room (( Moistinfog room (( Moistinfog room (( Moistinfog room

48 41 (( %rh (( %rh (( %rh (( %rh (( %rh (( %rh Cabrera(et(al( 1986( water immersed < <

49 42 (( water immersed < < (( water immersed < < (( water immersed < < (( water immersed < < (( water immersed < < (( water immersed < < (( water immersed < <

50 43 (( water immersed < < ( dmoist thenroom temp (( dmoist thenroom temp Whiting(1989( moist < < < < < < < 0.81 (( moist < < < < 0.81 (( moist < < < < 0.74 Whiting(1987( water immersed < <

51 44 (( water immersed < < (( water immersed < < (( water immersed < < (( water immersed < < (( water immersed < < (( water immersed < < (( water immersed < <

52 45 (( water immersed < < (( water immersed < < (( water immersed < < (( water immersed < < (( water immersed < < (( water immersed < < (( water immersed < <

53 46 (( water immersed < <

54 47 Appendix(B( Mixture(ID( 1.070:PC 1.070:25F Cube( FrequI ency( (khz)( ResistI ance( (Ω)( Resistivity( (Ω m)( Mortar(Cube(Test(Results( Average(Resistivity((((((((((((((((((((((( (Ω m)( 1(Day(( 3(Day( 7(Day( 28(day( ϕ(((((( ( )((((( Compressi Load(((((( ve( (kn)( Strength(((( (MPa)( Average(Compressive( Strength(((((((((((((((((((( (MPa)( ( Day(( 3( Day( 7( Day( 28( day(

55 :S 1.070:S

56 :PC 1.003:25F