Effect of elevated temperature on properties of geopolymer concrete: A review

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 09 Issue: 08 | Aug 2022 www.irjet.net p-ISSN: 2395-0072

Effect of elevated temperature on properties of geopolymer concrete: A review

S. D. Sayyad1 , H. S. Jadhav2

1PG Student, Department of civil engineering, Rajarambapu Institute of technology, Islampur, MH, 415411, India

2Professor, Department of civil engineering, Rajarambapu Institute of technology, Islampur, MH, 415411, India ***

Abstract - Geopolymers have been identified as apotentially effective alternativebindertoordinaryPortlandcement(OPC) for lowering carbon dioxide emissions and increasing waste recycling efficiency. Because of their availability and high silica and alumina concentrations, fly ash (FA) and groundgranulated blast-furnaceslag(GGBFS)hasbeenpreferredraw materials for geopolymer concrete (GPC). The FA/GGBFSbased GPC offers a green technological solution for long-term development. As a consequence, the specialized evaluation of FA/GGBFS-based GPC used to replace traditionalconcretehas become incredibly important, as the relevant study results on the FA/GGBFS-based GPC may stimulate further research and implementation of this green building material. The response process of geopolymers, as well as the characteristics and durability of fresh and hardened FA/GGBFS-based GPC when subjected to extreme temperatures, are examined in this paper. Because of their ceramic-like characteristics, geopolymers are oftenthoughttohavesuperiorfireresistance. Various experimental factors and their effects on the compressive strength of geopolymer concrete at increased temperatures have been researched, including specimen sizing, aggregate sizing, aggregate type and superplasticizer type, molarities of NaOH, and additional added water. The study identified specimen size and aggregate size as the two most important elements governing geopolymerperformance at high temperatures(800°C).Thethermalmismatchbetween the geopolymer matrix and the aggregatecausesstrengthloss at high temperatures.

Key Words: Elevated temperature, Fly ash, Ground granulated Blast furnace Slag, Geopolymer concrete, Compressive strength.

1. INTRODUCTION

Becauseofmanufacturingmethodsofconstituentmaterials such as cement binder, coarse and fine aggregates, and reactions in the cement hydration process, conventional Portlandcementconcrete,whichiscommonlyusedincivil construction,hasaconsiderableimpactonthegreenhouse effect.Accordingtoreports,thecementsectorcontributed roughly 5% of world CO2 emissions. Then, Geopolymer Concrete (GPC) emerged as one of the most significant technologies in the concrete industry for lowering carbon dioxide emissions in civil engineering operations. Geopolymer is created by the geopolymerization of

aluminosilicate materials such as fly ash, metakaolin, and silicafumewithanalkalineliquidactivatorsuchassodium hydroxideand/orsodiumsilicate. Incomparedtocement, the use of fly ash or silica fume in GPC manufacture decreased CO2 emissions by up to 5-6 times. As a result, expertsthroughouttheworldarepayingcloseattentionto thisalternativecement-freematerialforbothenvironmental andeconomicreasons.

When exposed to extreme temperatures, such as in a fire, concreteexperiencesmajorphysical-chemicalchanges.This exposure, among other things, can cause significant deterioration in the concrete, such as loss of strength, reduction of modulus of elasticity, and degradation of durability, as well as cracking, spalling, destruction of the bond between the cement paste and the aggregates, and gradualdeteriorationofthehardenedcementpaste.Because of moisture loss, the density of concrete reduces as temperaturerises.Thethermalandmechanicalqualitiesof concrete influence the fire resistance of structural components. These properties change dramatically with temperatureandarealsoaffectedbythecompositionand qualitiesofthematerials,aswellasthepaceofheatingand otherexternalfactors.

Significant study has been undertaken on geopolymer concrete, with mechanical and durability qualities being intensivelyexplored.However,nothingisknownaboutthe behaviorofgeopolymerconcreteathightemperatures.The majority of the published papers indicated the residual strength of geopolymer concrete measured at room temperaturefollowingexposuretoincreasedtemperatures of up to 800°C. The compressive strength of geopolymer concreteunderfireisextremelybeneficialinthedesignand stability of reinforced concrete constructions. There is currently little information available on the compressive strengthofgeopolymerconcreteatextremetemperatures. The behavior of geopolymer concrete at increased temperatures would differ from that of concrete due to thermal incompatibility between geopolymer paste and aggregates. The compressive strength of fly-ash-based geopolymerconcreteisinvestigatedinthisreviewworkat variousraisedtemperaturesof200,400,600,and800°C.

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 09 Issue: 08 | Aug 2022 www.irjet.net p-ISSN: 2395-0072

2. Literature Review

(Kotha & Rao, 2020) evaluated the compressive and flexuralstrengthofgeopolymerconcreteformedofMsand subjected to heat curing at 60°C and 70°C with varied activator solution ratios, molarities of alkaline solution exposed to increased temperature are investigated. When compared to heat cured cubes at 60 °C, the compressive strength of GPC cubes exposed to 200°C cured at temperature70°Cisdegradedbyabout3.2%,1.15%,and 4.5%for1:2.5ratioofactivatorsolutionwithmolaritiesat 12,16,and20molarityandabout1.35%,11.9%,and9.55% for 1:2 ratio of alkaline activator combination with concentrations of 12, 16, and 20 M of sodium hydroxide. Cubeswitharatiocontentof1:2at16molarityhavehigher strength than all other conditions that are heat cured at 60°C, whereas cubes with a ratio content of 1:2.5 at 20 molarity cured at 70°C have the lowest strength. As a consequence,thecompressivestrengthofGPCheatcuredat 60°C for 24 hours outperformed specimens cured at 70°C after being exposed to a high temperature to test thermal resistance.

( Luo, S.H., K.M, H.J.H, & Yu, 2021)analysesandshowsthe synergeticimpactofphysicochemicalcharacteristicssuchas crystallinephaseandbindergelstability,skeletonandbulk density,porestructure,crackingbehavior,andmechanical strengthofAAFSupto800°C.Tounderstandaboutcracking behavior,a quantitativeevaluationofthecrackiscreated. The findings indicate that fracture density has a linear correlation with ultrasonic pulse velocity. Before 100°C, fracturedensityandcompressivestrengthhaveapositive connection, while beyond 100°C, they have a negative association. The incorporation of slag into geopolymers reduces geopolymeric behaviors such as additional geopolymerization and viscous sintering, but also exacerbates thermal damage due to its modular structure and unstable hybrid gel. The AAF and AAFS conceptual modelsaredevelopedtodescribethedegradingmechanism of low slag containing geopolymers at increased temperatures

( Zhang, et al., 2020) examines the behavior of ambientcured and heat-cured low-calcium fly ash geopolymer concreteafterprolongedexposuretohightemperaturesThe concrete specimens were heated at 5°C/min to 100, 200, 400,600,800,and1000°C.Theeffectofincreasingexposure duration on geopolymer concrete was investigated using visual examination, mass loss, cracking extent, residual strength,andmicrostructureanalysis.Theoveralllengthof cross-section cracks and surface cracks peaked at 800°C beforedecliningat1000°C.Thefindingsrevealthatallthe concrete specimens could be heated at 600°C for 2 hours withoutlosingstrength.Forallexposuretemperatures,heatcured geopolymer concrete specimens had greater compressive strengths than ambient-cured specimens A crushingindexof7.7%mightbeconsideredthelowerlimit

forcoarseaggregateinordertosustaintheinitialconcrete's compressive strength at temperatures up to 600°C. Thus, SEM pictures demonstrate microstructural degradation, thermogravimetric analysis shows dehydration of geopolymer, and reduced strength of coarse aggregate as contributing reasons to strengths losses at temperatures over 600°C. Lastly, several prediction equations are developed that match very well with test findings of this workaswellasthosereportedintheliterature.

( L.Y. Kong & Sanjayan, 2009) The effect of higher temperature on geopolymer paste mortar and concrete preparedusingflyashasaprecursorisinvestigated.Sodium silicate and potassium hydroxide solutions were used to create the geopolymer. Several experimental factors, includingspecimensize,aggregatesize,aggregatetype,and superplasticizer type, have been investigated. The study identifiedspecimensizeandaggregatesizeasthetwomost importantelementsgoverninggeopolymerperformanceat hightemperatures(800°C).Largeraggregatesizesproduced good strength performances at both ambient and higher temperatures. The thermal mismatch between the geopolymermatrixandtheparticlesinitiatesstrengthlossin geopolymerconcreteathightemperatures.

(Y., K.M., H.J.H, & Qingliang, 2022) studiestheactivationof LSinconjunctionwithClassFflyash,aswellastheeffectof ladle slag on fly ash geopolymer, with an emphasis on activation, hydrates assembly, conversion process, and thermal behavior. The results suggest that the distinct reactionprocessofladleslaginanalkaliactivationsystem hasafavorableeffectonflyashgeopolymers.Theinitially hydrated CAH phases change into C-A-S-H in an alkaline environment rich in soluble Si, which not only delays conversion and increases mechanical strength but also preserves geopolymerization. The hybrid geopolymer system outperforms pure fly ash geopolymers in terms of thermal performance, especially at high temperatures. At high temperatures, more stable crystalline phases are generatedasladleslagreplacementincreases.With25wt.% ladleslagaddition,ahighresidualcompressivestrengthof 64.7MPaisattainedafter800°Cexposure,comparedto55.2 MPainpureflyashgeopolymers.

(Hager, Mateusz, & Katarzyna, 2021) The effect of temperatureexposure(upto1000°C)onthemicrostructure and mechanical characteristics of geopolymer mortars is assessed.Fourmixeswithflyashasthemajorprecursorand fouramountsofslagreplacement(0,10,30,and50wt.%) wereexamined.Thefollowingmechanicalperformancesand identificationtests were carriedout todetermine damage evolution: ultrasonic pulse velocity, scanning electron microscope,mercuryintrusionporosimetry,thermalstrain measurements, differential thermal analysis, and thermogravimetry. The study sought to create a mortar compositionthatisthermallystableathightemperatures. Although slag inclusion significantly enhances the

2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page626

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 09 Issue: 08 | Aug 2022 www.irjet.net p-ISSN: 2395-0072

mechanical properties of fly ash geopolymer mortar (compressivestrengthabove100MPa),themortarwithout slag addition performed better at high temperatures. At 200°C,producedmortarsincreasedtheirstrengthby30% and doubled their tensile strength. Furthermore, compressivestrengthrecoveryofupto90%at1000°Cwas reportedfordevelopedmixtures,revealingthepotentialof fly ash geopolymer as a high-temperature application material.

( Valencia Saavedra & de Gutiérrez, 2017) Alkaline activatedconcretesmadeofflyash(FA)andblastfurnace slag(GBFS),aswellasFAandPortlandcement(OPC)inan 80:20ratio,weresubjected totemperatures rangingfrom 25°C to 1100°C. The physicochemical and mechanical changes were then assessed. The results show that the activatedconcretesoutperformthecontrolconcretes(100 percent OPC). The residual strengths of the FA/GBFS and FA/OPC concretes at 1100°C are 15 and 5.5 MPa, respectively,buttheOPCconcretelost100%ofitsstrength.

The activated matrix densifies at temperatures exceeding 900°C, and crystalline phases including such sodalite, nepheline,albite,andakermanitearefound.

( Zhang, et al., 2020) offersa reviewofFA/GGBFS-based GPCusedtoreplacetraditionalconcretehasbecomecritical becausetheassociatedstudyresultsontheFA/GGBFS-based GPC may support further research and implementation of this green building material. The reaction process of geopolymers,aswellasthecharacteristicsanddurabilityof fresh and hardened FA/GGBFS-based GPC, are covered in this paper. Furthermore, the most recent statistics on the FA/GGBFS-based GPC are provided. The GPC offers great characteristicsandadiversesetofapplicationpossibilities. However, there remain barriers to its widespread use in engineering and industry. As a result, researchers and engineersmustdomorestudytogiveacomprehensivesetof theoryandtechnicalapplicationsfortheFA/GGBFS-based GPCsystem.

( Amin, Elsakhawy, Abu-Al-Hassan,&Abdelsalam,2022)

Industrialwastessuchasflyash,metakaolin,andgranulated blastfurnaceslagwereemployedasthefoundationforthis paper's high strength geopolymer concrete (HSGC). Four Portlandcement-basedhighstrengthconcrete(HSC)mixes were created for comparison with fifteen different geopolymerconcretemixes. All ofthemixtureswerecast, cured,andtested.Asfreshqualities,slumpandaircontent wereassessedforbothHSCandHSGCmixtures.Mechanical parameters examined and assessed were compressive strengthat3,7,28,and91days,splittingtensilestrength, flexural strength, and modulus of elasticity. Water permeabilitycoefficient,dryingshrinkageat3,7,14,21,28, 56,and91days,aswellastemperaturestudiesfrom100°C to 700 °C, were explored. The cement and geopolymer concrete mixes were analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX)

spectroscopy.Intermsoffreshproperties,thegeopolymer concretebasedonslagwith500kg/m3demonstrated225 mmslump,whereasintermsofhardenedproperties,themix contained200kgofmetakaolinwith300kgofslaghadthe greatest compressive strength in both early and late age 63.3,82.6MPa,respectively,aswellasthegreatestsplitting tensilestrength6.2MPa,flexuralstrengthreached9.2MPa, and modulus of elasticity was 37. Furthermore, the coefficientofpermeabilityfallswithincreasinggranulated blast furnace slag. Mineral additions helped to reduce dry shrinkage in geopolymer concrete. SEM pictures revealed thatthegeopolymermatrixhadmorescatteredsmall-sized holes,indicatingthatithadastrongercompressivestrength thantheotherexperimentalmixes.

( Toufigh & Alireza , 2021) based on the chemical compositions of its parts, gives a complete model for forecasting the compressive strength of fly ash-based geopolymerconcrete(FAGC).Toaccomplish thispurpose, 172 mix designs were collected from published studies between the years 2000 and 2020. To determine the relationship between input and output variables, the Bayesian linear regression technique was utilized. The findings emphasized the significance and influence of the chemicalcompositionsofflyashandsodiumsilicatesolution onthecompressivestrengthofFAGC,andtheseparameters could clearly explain discrepancies between optimal mix designsestablishedinprevious investigations.Finally,the suggestedmodelcouldaccuratelypredictthecompressive strengthoflowcalciumFAGC,savingtimeandmoney.When the intended compressive strength is between 10 and 75 MPa, the suggested model can correctly estimate the compressivestrengthofFAGC.

( Su, Xu, & Ren, 2015) carry out The mechanical characteristics of geopolymer concrete (GC) subjected to dynamic compression at extreme temperatures are investigatedexperimentally.Asthedatashow,weightlossis spectacular at temperatures ranging from ambient temperatureto200°C,aswellas600°Cto800°C.At200°C, thedynamiccompressivestrengthofGCincreasesmorethan atambienttemperature,butdropsdramaticallyat800°C.At extremetemperatures,thecriticalstrainisgreaterthanat ambient temperature. Its energy absorption capability is superiortothatofroomtemperatureat200°Cand600°C, respectively. However, at 400°C and 800°C, it performs worsethanatambienttemperature.

(Hui-Teng, et al., 2022) Thethermalstabilityofflyash(FA) and fly ash-ladle furnace slag (FA-LS) geopolymers was compared.FA-LSgeopolymerwascreatedbycombiningFA and LS (in an 80:20 weight ratio) with an alkali activator. Geopolymers were matured for 28 days at room temperature before being subjected to high temperatures (200°C - 1000°C). When compared to unexposed FA geopolymer, the compressive strength of FA geopolymers fellby6.5-38.4%from200°C(42.8MPa)to1000°C(24.0

2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page627

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 09 Issue: 08 | Aug 2022 www.irjet.net p-ISSN: 2395-0072

MPa) (38.9 MPa). When compared to unexposed FA-LS geopolymers, the compressive strength of FA-LS geopolymersreducedbyjust2.2-8.7%from200°C(43.1 MPa)to1000°C(39.2MPa)(40.5MPa).Asaresultoftheir superiorcompressivestrengthretention,FA-LSgeopolymers outperformedFAgeopolymersinmechanical andthermal performance.ThiswasduetothefactthattheexposedFA-LS geopolymersdidnotcrackandhadlowerbulkdensity(2.95.5%)andvolume(2.3-6.8%)changesthantheexposed FAgeopolymers(densitychangeof2.9-25.2%andvolume changeof2.3-19.5%),aswellaslowerwaterabsorption (7.4-13.2%)andapparentporosity(17.4-23.0%)(water absorptionof9–20%andapparentporosityof19–30%). The combined influence of LS as a filler and precursor, as well as the existence of coexisting C-A-S-H and N-A-S-H matrices, improved microstructure compactness in FA-LS geopolymers.CrystallinephasesweregeneratedinbothFA and FA-LS geopolymers at high temperatures, but FA-LS geopolymershadahighercrystallinecontent(53.0-74.5%) thanFAgeopolymers(40.3-69.6%),resultinginincreased strength in FA-LS geopolymers. The final compressive strength of geopolymers was influenced by porosity, microstructurecompactness,internalandexternaldamages, andthedevelopmentofcrystallinephases.Theinclusionof LSeffectivelyenhancedthethermalandstructuralintegrity of FA geopolymers. Instead of FA geopolymers, FA-LS geopolymersarerecommendedasaheat-resistantmaterial.

(Hai Yan Zhang, Venkatesh Kodur, Bo Wu, Jia Yan, &

Sheng Yuan, 2017) offersexperimental findings on thebondbehaviorofgeopolymerconcreteandrebar.Pulloutexperimentswereperformedongeopolymer concrete specimensimplantedwithplainandribbedrebarsatroom temperatureandafterexposureto100,300,500,and700°C. The test specimens were prepared using two batches of geopolymerconcretewithcompressivestrengthsof48and 64MPa,respectively,andfiverebardiameters(of10,12,14, 18, and 25 mm). Benchmark tests on ordinary Portland cement(OPC)concretespecimenswerealsoperformed.The resultsoftheseexperimentsdemonstratethatgeopolymer concrete displays little bond strength decline up to 300°C butsuffersseveredeteriorationafterthat.Thetestresults show that the rate of bond strength deterioration in geopolymerconcreteislikethatofsplittingtensilestrength butmorethanthatofcompressivestrength.Furthermore, the findings suggest that geopolymer concrete has equivalentorsuperiorbondcharacteristicsasOPCconcrete, both at room temperature and after exposure to higher temperatures. Thus, where fire resistance is a primary design factor, geopolymer concrete can be a viable alternative to OPC concrete in reinforced concrete structures.

(F. U. A. Shaikh & V. Vimonsatit, 2014) Thecompressive strengthoffly-ash-basedgeopolymerconcretesat200,400, 600, and 800°C is shown. The results reveal that fly-ashbasedgeopolymerconcreteslosetheirinitialcompressive

strengthatallhighertemperaturesupto400°C,regardless ofmolarityorcoarseparticlesize.Allgeopolymerconcretes showedanimprovementincompressivestrengthat600°C compared to 400 °C. It is, however, lower than that measuredatroomtemperature.At800°C,thecompressive strength of all geopolymer concretes is lower than that at ambient temperature, with the exception of geopolymer concrete containing 10 M NaOH. At 600 and 800°C, the compressive strength of the latter rose. Higher molarity NaOH solution geopolymer concretes (e.g., 13 and 16 M) demonstratemorecompressivestrengthlossat800°Cthan 10MNaOH.Atincreasedtemperatures,geopolymerconcrete withsmallersizecoarseaggregateretainsthemajorityofits initialcompressivestrength.Atallincreasedtemperatures, the addition of more water reduces the compressive strength of geopolymer concretes. However, prolonged steam curing enhances compressive strength at high temperatures.

Yan Zhang, Venkatesh Kodur, Bo Wu, Liang Cao, & Fan Wang, 2016) mechanicalandthermalcharacteristicsof geopolymermortarproducedbyalkalinesolutionactivating metakaolin and fly ash mix Bending, compressive, tensile, and bond strength tests were performed on large sets of geopolymer mortar, Portland cement mortar, and commerciallyusedrepairmortarspecimensatambientand increasedtemperatures.Geopolymerpasteandmortarwere also subjected to thermogravimetry and differential scanning calorimetry analyses, as well as dilatometric testing. These studies reveal that geopolymer mortar has higher temperature-induced deterioration in bending and tensilestrengthbutlowertemperature-induceddegradation in compressive and bond strength than conventional Portland cement mortar and widely used repair mortar. Specifically, the bond strength of geopolymer mortar on cement mortar or concrete substrate is close to or even higher than that of commercially used repair mortar throughout 25–700°C range. The microstructural damage due to temperature-induced dehydration and dehydroxylations, and thermal incompatibility between geopolymerpasteandaggregatesisthemainreasonforthe strength degradation of geopolymer mortar at high temperatures.

(Daniel L.Y. Kong & Jay G. Sanjayan, 2009) Theeffectof higher temperature on geopolymer paste, mortar, and concrete prepared using fly ash as a precursor is investigated. Sodium silicate and potassium hydroxide solutions were used to create the geopolymer. Several experimental factors, including specimen size, aggregate size, aggregate type, and superplasticizer type, were investigated. The study identified specimen size and aggregate size as the two most important elements governing geopolymer performance at high temperatures (800°C). Larger aggregate sizes produced good strength performancesatbothambientandhighertemperatures.The thermalmismatchbetweenthegeopolymermatrixandthe

2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page628

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 09 Issue: 08 | Aug 2022 www.irjet.net p-ISSN: 2395-0072

particlescausesstrengthlossingeopolymerconcreteathigh temperatures. The rate of aggregate expansion with temperatureisanimportantcomponentintheperformance ofgeopolymerconcreteathightemperatures.

(Sasi Rekha M. & Sumathy S.R., 2021) createdinorderto better understand the feasibility of Geopolymer Concrete curedatroomtemperatureinthebuildingsector,aswellas theinfluenceofmolarityonstrengthqualitiesByvaryingthe molarities of sodium hydroxide, five different types of GeopolymerConcretemixeswerecreated:4M,6M,8M,10M, and12M.Fortheaforementionedmolarities,compressive strengths(1,3,7,14,and28days),splittingtensilestrengths (7,14,and28days),andflexuralstrengthsat28dayswere investigated. In general, increasing molarity improves compressivestrength.Theintegrationofcalciumcontained inGGBShasincreasedthestrengthatearlyagesinFAand GGBS based Geopolymer Concrete. Except for 4M geopolymer concrete, the 3-day and 7-day compressive strengthswereroughly50-75%and80-93%ofthe28-day compressive strength, respectively. At 28 days, the maximum strength of 8M Geopolymer Concrete reached 57.53MPa.Non-Destructivetests(NDT)(ReboundHammer andUltrasonicpulsevelocity)wereperformedatasameage ofcuringtovalidatethecompressivestrengthpredictedby the Destructive test (DT). A regression analysis is also performedbetweenthecompressivestrengthdeterminedby DT and the NDT results. The obtained linear regression equationswerewellassociatedwiththeexperimentaldata, withR2 valuesrangingfrom0.8970-0.9967.

3. CONCLUSIONS

Thegeopolymerreactionprocess,workability,mechanical characteristics, and durability of fresh and hardened FA/GGBFS-based GPC were all examined. The following conclusionscanbetakenfromthereviewresults:



Accordingtothetalks,geopolymerconcreteoffers significantpotentialforusageasabuildingmaterial in a variety of applications. A variety of critical features have been studied, and extremely high strengthshavebeenachieved.

80-93% of the 28-day compressive strength, respectively. 

ThecompressivestrengthofGeopolymerConcrete typically increases as the molarity of sodium hydroxideincreases.Thecreationofbetteraluminasilicatenetworksduringgeopolymerization,aswell as high melting temperature phases such as nepheline (NaAlSiO4), albite (NaAlSi3O8), and tridymite(SiO2),resultedinincreasedcompressive strength at all raised temperatures. Because of further geopolymerization over time, geopolymer concrete that experienced longer heat curing displayedbettercompressivestrengthatallraised temperatures. 

The strength at elevated temperatures is proportional to the size of the geopolymer paste specimens. Thermal cracking is caused by the substantial temperature gradient between the surfaceandcoreofthespecimencross-section.Asa result, thermal incompatibility caused by a temperaturegradientismostlikelythecauseofthe sizeimpacts.Becauseofthepossibilityoflessmicro cracking in the ITZ of particles in the former, geopolymer concrete using smaller size coarse aggregatesdisplayedslightlygreatercompressive strength at all raised temperatures than that including bigger coarse aggregates. The rate of aggregate expansion with temperature is an important component in the performance of geopolymerconcreteathightemperatures.

Because coarse particles and fly ash geopolymer pastearethermallyincompatible,thecompressive strength of geopolymer concretes declined at increased temperatures up to 400°C, which is comparable with OPC concrete. However, the compressivestrengthofgeopolymerconcreteswas greaterat600°Cand800°Cduetothemoresteady contraction of geopolymer paste at those temperatures.



BecausetheprimaryrawmaterialsutilisedinGPC are industrial wastes such as FA and GGBFS, its usagecanminimiseCO2 emissions,simplifywaste recycling,andimprovesocietalsustainability.Asa result,theFA/GGBFS-basedGPCmightpossiblybe usedasasubstituteforOPC.However,thiswillonly happeniftherawmaterialsupplychainisefficient.

Thefinalcompressivestrengthofgeopolymerswas impactedbyporosity,microstructurecompactness, internal and external damages, and the developmentofcrystallinephases.



The integration of calcium contained in GGBS has increasedthestrengthatearlyagesinFAandGGBSbasedGeopolymerConcrete.The3-dayand7-day compressive strengths were around 50-75% and

Based on the findings of this study, geopolymer concrete manufacturing should be encouraged in order to reduce the impact of global warming by successfully using industrial by-products and producingcement-freeconcrete.

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 09 Issue: 08 | Aug 2022 www.irjet.net p-ISSN: 2395-0072

REFERENCES

[1] Amin, M., Elsakhawy, Y., Abu el-hassan, K., & Abdelsalam, B. A. (2022). Behavior evaluation of sustainable high strength geopolymer concrete basedonflyash,metakaolin,andslag. Case Studies in Construction Materials, 16,e00976.

[2] Luo,Y.,Li,S.H.,Klima,K.M.,Brouwers,H.J.H.,&Yu, Q. (2022). Degradation mechanism of hybrid fly ash/slag based geopolymers exposed to elevated temperatures. Cement and Concrete Research, 151, 106649.

[3] Su, H., Xu, J., & Ren, W. (2016). Mechanical properties of geopolymer concrete exposed to dynamic compression under elevated temperatures. Ceramics International, 42(3),38883898.

[4] Toufigh, V., & Jafari, A. (2021). Developing a comprehensive prediction model for compressive strength of fly ash-based geopolymer concrete (FAGC). Construction and Building Materials, 277, 122241.

[5] Saavedra, W. G. V., & de Gutiérrez, R. M. (2017). Performanceofgeopolymerconcretecomposedof fly ash after exposure to elevated temperatures. Construction and Building Materials, 154,229-235.

[6] Zhang,H.,Li,L.,Yuan,C.,Wang,Q.,Sarker,P.K.,& Shi,X.(2020).Deteriorationofambient-curedand heat-cured fly ash geopolymer concrete by high temperatureexposureandpredictionofitsresidual compressive strength. Construction and Building Materials, 262,120924.

[7] Zhang,P.,Gao,Z.,Wang,J.,Guo,J.,Hu,S.,&Ling,Y. (2020). Properties of fresh and hardened fly ash/slag based geopolymer concrete: A review. Journal of Cleaner Production, 270,122389.

[8] Kong, D. L., & Sanjayan, J. G. (2010). Effect of elevatedtemperaturesongeopolymerpastemortar andconcrete. Cement and concrete research, 40(2), 334-339.

[9] Shaikh, F. U. A., & Vimonsatit, V. (2015). Compressivestrengthoffly‐ash‐basedgeopolymer concrete at elevated temperatures. Fire and materials, 39(2),174-188.

[10] Hager,I.,Sitarz,M.,&Mróz,K.(2021).Fly-ashbased geopolymer mortar for high-temperature

application–Effect of slag addition. Journal of Cleaner Production, 316,128168.

[11] Zhang, H. Y., Kodur, V., Wu, B., Cao, L., & Wang, F. (2016). Thermal behavior and mechanical propertiesofgeopolymermortarafterexposureto elevated temperatures. Construction and Building Materials, 109,17-24.

[12] Zhang,H.Y.,Kodur,V.,Wu,B.,Yan,J.,&Yuan,Z.S. (2018). Effect of temperature on bond characteristics of geopolymer concrete. Construction and Building Materials, 163, 277-285.

[13] Hui-Teng, N., Cheng-Yong, H., Yun-Ming, L., Abdullah,M.M.A.B.,Pakawanit,P.,Bayuaji,R.,...& Shee-Ween, O. (2022). Comparison of thermal performance between fly ash geopolymer and fly ash-ladlefurnaceslaggeopolymer. Journal of NonCrystalline Solids, 585,121527.

[14] Yasaswini, K., & Rao, A. V. (2020). Behaviour of geopolymer concrete at elevated temperature. MaterialsToday:Proceedings, 33,239244.

[15] SasiRekha,M.,&Sumathy,S.R.(2021).Astudyon cement-free geopolymer concrete incorporated with industrial waste cured at open environment fordifferentmolaritiesofsodiumhydroxide.

[16] Luo, Y., Klima, K. M., Brouwers, H. J. H., & Yu, Q. (2022). Effects of ladle slag on Class F fly ash geopolymer: Reaction mechanism and high temperature behavior. Cement and Concrete Composites, 129,104468.

2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal |