G.2049Page1GlobalResearchjournalofNaturalScience&Technology(GRJNST)Volume:04-Issue2(2026),2049ISSNP:2790-7643ISSNE:2790-7651www.grjnst.nethttps://doi.org/10.53762/grjnst.04.02.01OptimizationofGGBSasaPartialReplacementofCementforEnhancedStrengthandDurabilityofSustainableConcreteReceived:26December2025.Accepted:19January2025.Published:03March2026TariqAliDepartmentofCivilEngineering,TheIslamiaUniversityofBahawalpur,Bahawalpur,Pakistanali_tariq06@iub.edu.pkAbdulSalamBullerDepartmentofCivilEngineering,NEDUniversityofEngineering&TechnologyKarachi,Pakistanengr.salam@cloud.neduet.edu.pkSamreenShabbirDepartmentofCivilEngineering,DawoodUniversityofEngineering&TechnologyKarachi,Pakistansamreen.shabbir@yahoo.comMuhammadAzamDepartmentofCivilEngineering,TheIslamiaUniversityofBahawalpur,Bahawalpur,Pakistanengr.azam35@gmail.comMujahidHussainLashariDepartmentofCivilEngineering,TheIslamiaUniversityofBahawalpur,Bahawalpur,Pakistandmhlashari@gmail.com*CorrespondingAuthor:Dr.ZaheerAhmed(dr.zaheer@kfueit.edu.pk)Copyright©2026GRJNST.ThisarticleispublishedunderanOpenAccessmodel.ItismadeavailabletothepublicunderthetermsoftheCreativeCommonsAttribution4.0International(CCBY4.0)license,whichpermitsunrestricteduseanddistributionGRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2049https://doi.org/10.53762/grjnst.04.02.01G.2049Page2Abstract:Concreteisoneofthemostcommonbuildingmaterialsintheworld.Ithasgreatcompressivestrength,butitisnotverydurableorsustainablebecauseitreliesonordinaryPortlandcement(OPC).GroundGranulatedBlastFurnaceSlag(GGBS),aby-productofthesteelindustry,wasusedasapartialreplacementforOrdinaryPortlandCement(OPC)toimprovethemechanicalanddurabilityperformanceofconcrete.ThemassproportionsforreplacingcementwithGGBSinconcretemixeswere0%,10%,20%,30%,and40%.Themixratiowas1:1.5:3,andthewater-to-cementratiowas0.45.Mechanicalperformancewastestedbymeasuringthecompressivestrength,splittensilestrength,flexuralstrength,andsurfacehardness(usingthereboundhammertest).Fordurabilityperformancecarbonationdepthandwaterpermeabilitytestswereconducted.Accordingtothefindings,GGBSproducedthehighestcompressive,tensile,andflexuralstrengthswhen20%ofOPCwassubstituted.Italsoimprovedsurfacehardnessanddecreasedpermeability,indicatingincreaseddurability.Mechanicalstrength,resistancetocarbonation,andpermeabilityalldecreasedabovethispoint.TheresultsvalidatetheviabilityofemployingGGBSasasustainablebinder,whichlowersCO2emissionsandcementconsumptioninenvironmentallyfriendlybuilding.Keywords:Concrete,GGBS,SupplementaryCementitiousMaterials,MechanicalStrength,Durability,SustainableConstructionIntroductionhemostpopularbuildingmaterialintheworld,concreteisrenownedforitshighworkability,versatility,andcompressivestrength.Itscreationanduseserveasthefoundationforthedevelopmentofinfrastructure,particularlyindevelopingnations.However,conventionalconcretehasasignificantenvironmentalcost,mostlybecauseitusesOrdinaryPortlandCement(OPC).About7–8%oftheworld'sCO₂emissionscomefromthecementindustryalone,mostlyfromthecalcinationoflimestoneandtheuseoffossilfuelsinitsmanufacture.Becauseoftheurgentneedtoslowdownclimatechange,researchersandengineersarelookingintolow-carbonoptionslikeusingindustrialbyproductsassupplementarycementitiousmaterials(SCMs).GroundGranulatedBlastFurnaceSlag(GGBS)isaverypopularSCM.Whenmoltenslag,whichisaby-productofmakingironinablastfurnace,coolsquickly,itbecomesgroundgranulatedblast-furnaceslag(GGBS),whichisalatenthydraulicmaterial.Thereactionofitscalcium,silica,andalumina-richcompositionwithcalciumhydroxidegivesitstrengthanddurability.ThisishowordinaryPortlandcement(OPC)turnedintomorecalciumsilicatehydrate(C-S-H).TheincorporationofGGBSintoconcretemixtureshasbeenshowntoimproveseveralperformancecharacteristicssuchaspermeability,chlorideandsulphateresistance,reducedalkali-silicareactionandporestructurerefinement.GRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2049https://doi.org/10.53762/grjnst.04.02.01G.2049Page3SeveralstudieshavebeenundertakenontheuseofGGBSinconcretemixtures.Dinakaretal.[32]intheevaluationofhigh-volumeGGBSconcreteincreasedthedurabilityandporosityrefinementalsoupto50%replacement[1].AccordingtoAhmadetal.Resultsofpreviousstudiesshowedthatat20%GGBSreplacementcontinuedpozzolanicreactionspromotedcompressiveandsplittensilestrengthupto8weeks,particularlyat28and56days[2].InthestudyofHabertetal.,theGGBSenvironmentalbenefitswerehighlighted.(2020)bymentioningthatsignificantreductionsinembodiedCO₂wereachievedwithoutcompromisingdurability.AccordingtoKannanetal.GGBSenhancesthermalcrackingresistanceandchemical-resistant.[3]However,theslowreactivityofGGBSrelativetoOPCmaynegativelyaffectthestrengthperformanceintheinitialperiodsoflife[4].GGBS-modifiedconcretemayshowdelayedstrengthgain,increasedcarbonationdepth,andvariableworkabilitydependingonfinenessandcuringconditions,accordingtoUmapathyetal.[4]andSequeiraetal[5].Singhetal.[6]stressedtheimportanceofstrikingabalancebetweenperformancetrade-offsandenvironmentalbenefits,particularlywhensubstitutingGGBSformorethan30%OPC.ManyotherhaveinvestigatedthemechanicalanddurabilityperformanceofconcretebyaddingdifferentSCMinconcrete[7–9]Detailedstudiesassessingthecombinedmechanicalanddurabilityproperties,particularlyunderstandardizedcuringconditions,arestillscarce,despitethefactthattheadvantagesofGGBShavebeenwidelypublicized.Numerousearlierstudiesconcentrateonmechanicalperformanceorparticulardurabilitymetrics,suchaschlorideingressorsulfateresistance.Furthermore,themajorityofresearchusesmaterialsfromparticulargeographicalareas,whichmakesitchallengingtogeneralizethefindings.RegionallybasedstudiesthatemploylocallyaccessibleOPC,aggregates,andGGBSareobviouslyneeded.Thesestudiesshouldprovideacomprehensiveperformanceevaluationthatincludesslump,compressive,tensile,andflexuralstrengthinadditiontocarbonationandpermeabilityresistance.ThepresentstudyaimstobridgetheresearchgapsidentifiedthroughacomprehensiveexperimentalprogramthatassessesconcretemixtureswithpartialcementreplacementwithGGBS.Goals:ToassesstheinfluenceofvaryingpercentagesofGGBSreplacement(10%,20%,30%,and40%)onvarioustestparametersincludingmechanicalanddurabilitywereevaluated.TodeterminetheeffectsofGGBSondurabilityindicessuchassurfacehardness,waterpermeabilityandcarbonationresistanceofconcrete.TheaimistoestablishinlocalmaterialandcuringconditionstheoptimumlevelofreplaceableGGBSthatprovidesthebestcombinationofdurability,mechanicalperformances,andyessustainability.GRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2049https://doi.org/10.53762/grjnst.04.02.01G.20492.ExperimentalProgram2.1MaterialsPage4Theexperimentalprogramincludedmaterialsobtainedfromlocalsupplierstoensurethatitwasrealisticandappropriate.Belowisalistofthecomponentsthatwereused:Cement:ThemainbinderwasOPCTypeI,whichcompliedwithASTMC150standards.Itscompressivestrength,consistency,andsettingtimewereevaluated.FineAggregates:Goodworkabilityandgradationwereguaranteedbya50:50blendofnaturalsandfromlocalmarket.CoarseAggregates:5–19mmcrushedstonesfromthelocalmarkerwereusedformakingofconcretesamples.Thespecificgravityoftheaggregatesrangedfrom2.64to2.69.Water:ASTMC1602-compliantcleantapwaterthatcanbeusedtomixandcureconcrete.GGBS:Anearbysteelmillprovidedthegroundgranulatedblastfurnaceslag.ItmetASTMC989standardswithaBlainefinenessof410m²/kgandaspecificgravityof2.89.2.2MixProportionsAllmixeshadaconsistentwater-to-cementratio(w/c)of0.45andavolumetricratioof1:1.5:3(cement:fineaggregate:coarseaggregate).At0%(control),10%,20%,30%,and40%byweight,GGBSwasaddedtopartiallyreplaceOPC.ThemixproportionsandidentificationlabelingarecompiledinTable1.Table1:MixproportionsofmaterialsusedinthisstudyMixCementGGBSIDM0M10M20M30M40(%)10090807060(%)010203040OPC(kg)350315280245210GGBSFineAgg.CoarseAgg.Water(kg)03570105140(kg)525525525525525(kg)10501050105010501050(kg)157.5157.5157.5157.5157.52.3SpecimenPreparationArevolvingdrummixerwasusedtomixandbatchtheconcreteforeachmix.Forthefirsttwominutes,thedryingredientsOCC,GGBS,sand,andcoarseaggregateswerecombined.TocreateaGRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2049https://doi.org/10.53762/grjnst.04.02.01G.2049Page5consistent,homogenousmixture,waterwasthenaddedgraduallywhilethemixturewasbeingmixedforanadditionalthreeminutes.StandardsteelmoldswereusedtocasttheconcretesamplesasshowninFigure1.150mmx150mmx150mmcubes:Fortestsofwaterpermeability,carbonation,reboundhammer,andcompressivestrength.Forsplittensilestrengthtests,usecylindersthatmeasure150mmindiameterby300mminheight.Fortestingflexuralstrength,useprisms(160mmx40mmx40mm)asshowninFigure1.Toguaranteecompactionandremoveairvoids,allspecimenswerevibratedwithatablevibratoraftercasting.Aftercoveringthemoldswithplasticsheets,theywereleftaloneforafullday.Specimenswerethendemoldedandmovedtoacuringtankwherethewaterwaskeptat23±2°Cuntiltheyweretestedat7and28days.(a)(b)(c)Figure1:Specimendetails(a)cubesample(b)cylindricalsample(c)beamsample2.4TestingMethodsThemechanicalanddurabilitypropertieswereexaminedconsideringthefollowingstandardoperatingprocedures:SlumpTest(ASTMC143):Determinedhowworkableandconsistentfreshconcretewas[10].CompressiveStrength(ASTMC39):Usingahydrauliccompressionmachine,cubespecimensweretestedat7and28days[11].SplitTensileStrength(ASTMC496):Measuredoncylindricalspecimensafter28days[12].FlexuralStrength(ASTMC78):Testedonprismspecimensat28daysusingthethird-pointloadingmethod.Thesurfacehardnessofthetopfaceofconcretecubeswasmeasuredusingthereboundhammertest(ASTMC805)[13].CarbonationDepth:After28days,thecolorchangewasmeasuredaftercubesweresplitandaphenolphthaleinindicatorsolutionwassprayedonthem[14].3.ResultsandDiscussions3.1Workability-SlumpTest:GRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2049https://doi.org/10.53762/grjnst.04.02.01G.2049Page6Figure2showstheslumptestresults;slumptestresultsdemonstrateadefinitedeclineinworkabilityastheamountofGGBSincreases.Highworkabilitywasindicatedbythecontrolmix(M0),whichhadthehighestslumpvalueof110mm.ForGGBS-modifiedmixes,theslumpvaluesgraduallydroppedto70mm(M40),80mm(M30),90mm(M20),and100mm(M10).ThisdecreaseisexplainedbytheGGBSparticles'finersizeandlargersurfacearea,whichabsorbmorewaterandlowertheamountoffreewaterthatcanflow.Umapathyetal.(2014)reportedsimilartrends,findingthatahigherGGBScontentreducedslumpbecauseofitsslowerearlyreactivityandhigherwaterdemand.Allmixesretainedworkableconsistenciesappropriateforconstructioninspiteofthisreduction.Figure2:SlumtestresultsforeachconcretemixmadewithGGBS3.2CompressiveStrength:Figure3showshowthecompressivestrengthchangedover7and28days.Thecontrolmix(M0)reached30.5MPaat7daysand39.8MPaat28days.Thehigheststrength,withcompressivestrengthsof35.2MPaat7daysand45.1MPaat28days,was13.3%higherthanthecontrolM20.Improvedparticlepackingandinitialhydrationareresponsiblefortheearly-agegain,whereasthepozzolanicreactionthatformsmoreC-S-Hisresponsibleforthelong-termstrength.Compressivestrengthdroppedto40.7MPaand36.2MPaat30%and40%replacementlevels,respectively,asaresultofslowerGGBSreactivityandcementitiouscontentdilution.GRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2049https://doi.org/10.53762/grjnst.04.02.01G.2049Page7Figure3:CompressiveStrengthvaluesofeachconcretemixmadewithGGBSThesefindingssupportoptimalperformanceat20%GGBSreplacementandareinlinewiththoseofDinakaretal.(2013)andHussainetal.(2020).3.3SplitTensileStrength:Similarpatternstocompressivestrengthwereobservedinthesplittensilestrengthresultsat28days(Figure4).M20showedthehigheststrengthof3.92MPa,a14.6%increase,whilethecontrolmixreached3.42MPa.At3.75MPa,M10exhibitedenhancedtensilestrengthaswell.Tensilestrengthdecreasedto2.98MPa(M40)and3.25MPa(M30)after20%.AlthoughlowercontentsindicateinadequatehydrationofGGBS(at28days),theimprovementat20%isattributedtodensermatrixandbondstrength.Ahmadetal.Thesametrendsweredocumentedby(2022),whofoundthatthegreatestcompressivestrengthwasfor15–C20%GGBS.GRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2049https://doi.org/10.53762/grjnst.04.02.01G.2049Page8Figure4:SplitTensileStrengthvaluesofeachconcretemixmadewithGGBS3.4FlexuralStrength:At28days,moderateGGBScontentsremarkablyimprovedflexuralstrength(Figure5).M20increased5.42MPa(12.4%from4.82MPaforM0.)Thisenhancementhasbeenconnectedtobettermatrixcontinuityandamorerefinedporestructure.GRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2049https://doi.org/10.53762/grjnst.04.02.01G.2049Figure5:GGBSMixesshowingFlexuralstrengthatdifferentlevelsThelesserflexuralstrengthsof5.10MPaand4.65MPaforM30andM40mixesrespectivelycanbeattributedtothedelayedpozzolanicreactivityandlessnumberofavailableOPC.ThepatternsareconsistentwithfindingsfromKannanetal.(2021),whofoundthatGGBSproducedmaximumPage9flexuralstrengthof15–25%.3.5ReboundHammerTest:Figure6displaysthesurfacehardnessfindingsfromthereboundhammertest.Forthecontrolmix,thereboundnumberaveraged32.ThemixesM10andM20recordedavalueof33and34respectively,reflectsincreasedsurfacehardness.Figure6:ReboundhammertestvaluesofeachconcretemixmadewithGGBSHowever,M30andM40reducedto30and28respectively,whichprovedthephysicaltestresultsthatshowedthestrengthdecrease.ThesefindingsalignwiththeresultsbySequeiraetal.Asobservedby[25],incompletehydrationathigherGGBScontentwaslinkedtolowersurfacehardness.GRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2049https://doi.org/10.53762/grjnst.04.02.01G.20493.6CarbonationDepth:Page10However,thecarbonationtestresults(figure7)confirmthatcarbonationdepthwasgraduallyheightenedwiththeriseinGGBSproportion.Thedepthwas1.8mmforM10and1.9mmforM20whileitwasfoundtobe1.7mmforcontrolmix.M30andM40deepmeasuredare2.4mmand3.1mmrespectively.Asdepthincreased,higherGGBSlevelsdecreasedtheamountofCa(OH)₂availabletobuffercarbonation.However,goodperformancewasconfirmedbythecarbonationresistanceat20%replacement,whichremainedacceptable.ThesefindingsareinlinewiththoseofHabertetal.(2020),whofoundthatGGBScontentsabove25%increasedcarbonationsusceptibility.Figure7:CarbonationdepthvaluesofeachconcretemixmadewithGGBS4.ConclusionsThemechanicalanddurabilitypropertiesofconcretethatused10%,20%,30%,and40%replacementlevelsofgroundgranulatedblastfurnaceslag(GGBS)asapartialcementsubstitutewereinvestigatedinthisstudy.Theresultsdemonstratedthat,whenappliedsparingly,GGBScangreatlyimproveconcrete'sperformance.Thefollowingarethemainconclusions:✓Testresultsindicatedthata20%replacementlevel(M20)exhibitedthemostbalancedandsuperiorperformanceacrossallparameterstested.BesideshavingthelowestcarbonationGRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2049https://doi.org/10.53762/grjnst.04.02.01G.2049Page11depth(1.9mm),thismixachievedthehighestcompressivestrength(45.1MPaat28-day),optimalsplittensile(3.92MPa)andflexuralstrength(5.42MPa).MostoftheseimprovementsarelinkedtothesynergisticimpactofGGBSinducedmicrostructuralcompactionandpozzolanicactivityaswellasabettermatrix,finesporestructure,anddenserinterfacialtransitionzones(ITZs).✓Incontrast,duetothelowerreactivityofGGBSandthelowercementitiouscontentwithhigherlevelsofreplacement(atlevelsabove20%),theperformancedecreased(particularlyat40%).Higherreplacementlevelsalsocorrelatewithincreasedcarbonationdepthandwaterpermeability,whichfurthersuggeststhatasslagcontentincreaseswithoutlongcuringtimes,limitationsappear.✓35%replacedwithGGBSachievedstructuralfunctionwithlowerOPCconsumption(20%>)bringingdownthecarbonfootprintintheconstructionprocesswhichhadaninfluenceenvironmentally.✓Futurework,therefore,mustfocuson(i)long-termperformanceforfieldexposureconditions,(ii)applicationofhybriduseofGGBSwithotherSCMs,and(iii)microstructuralcharacterization(SEM/XRD)forabetterunderstandingoftheobservedtrendsindurabilityandhydrationkinetics.OneapproachtodevelopingstrongandsustainableinfrastructuresystemsistoblendGGBSintoconventionalconcrete.References[1]Dinakar,P.,Sethy,K.P.,&Sahoo,U.C.,(2013).Designofself-compactingconcretewithgroundgranulatedblastfurnaceslag.Materials&Design,43,161–169.[2]Ahmad,J.,Kontoleon,K.J.,Majdi,A.,Naqash,M.T.,Deifalla,A.F.,BenKahla,N.,Isleem,H.F.,&Qaidi,S.M.A.,(2022).Acomprehensivereviewonthegroundgranulatedblastfurnaceslag(GGBS)inconcreteproduction.Sustainability,14,8783.[3]Kannan,V.,&RajaPriya,P.,(2021).Evaluationofthepermeabilityofhighstrengthconcreteusingmetakaolinandwoodashaspartialreplacementforcement.SNAppliedSciences,3,90.[4]Umapathy,U.,Mala,C.,&Siva,K.,(2014).Assessmentofconcretestrengthusingpartialreplacementofcoarseaggregateforwastetilesandcementforricehuskashinconcrete.InternationalJournalofEngineeringResearchandApplications,4,72–76.GRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2049https://doi.org/10.53762/grjnst.04.02.01G.2049Page12[5]Sequeira,L.,Forero,J.,Bravo,M.,Evangelista,L.,&deBrito,J.,(2023).DurabilityofconcretewithpartialreplacementofPortlandcementbyincorporatingreactivemagnesiumoxideandflyash.Materials,16,2670.[6]Singh,R.P.,Vanapalli,K.R.,Jadda,K.,&Mohanty,B.,(2024).Durabilityassessmentofflyash,GGBS,andsilicafumebasedgeopolymerconcretewithrecycledaggregatesagainstacidandsulfateattack.JournalofBuildingEngineering,82,108354.[7]Buller,A.S.,Ali,T.,Shabbir,S.,Zaheer,S.A.,Khoso,S.,&Mata,L.A.,(2023).EffectOfFlyAshAndPolypropyleneFibersOnMechanicalAndDurabilityPerformanceOfEarlyAgeGreenConcreteForFutureSustainableDEVELOPMENT.InternationalJournalofEnergy,EnvironmentandEconomics,31,457–469.[8]Ali,T.,Saand,A.,Bangwar,D.K.,Buller,A.S.,&Ahmed,Z.,(2021).Mechanicalanddurabilitypropertiesofaeratedconcreteincorporatingricehuskash(RHA)aspartialreplacementofcement.Crystals,11,604.https://doi.org/https://doi.org/10.3390/cryst11060604.[9]Buller,A.S.,Buller,A.M.,Ali,T.,Tunio,Z.A.,Shabbir,S.,&Malik,M.A.,(2021).ExperimentalCharacterizationofBacterialConcreteAgainstMechanicalandDurabilityPerformance.Engineering,Technology&AppliedScienceResearch,11,6703–6707.https://doi.org/10.48084/etasr.3983.[10]ASTM,C.,(2003).143/C143M-03.StandardTestMethodforSlumpofHydraulic-CementConcrete”,ManualBookofASTMStandards,4,.[11]ASTMStandarC39/C39M,(2016).“TestMethodforCompressiveStrengthofCylindricalConcreteSpecimens1.”ASTMInternational,04,1–7.https://www.astm.org/Standards/C39.htm.[12]Aggregates,A.I.C.C.onC.andC.,StandardTestMethodforSplittingTensileStrengthofCylindricalConcreteSpecimens1,ASTMinternational,.[13]ASTM,(2015).D790-03-StandardTestMethodforFlexuralPropertiesofUnreinforcedandReinforcedPlasticsandElectricalInsulationMaterials.ASTMStandards,1–11.[14]Standard,A.,(1999).Standardtestmethodforcorrosionpotentialsofuncoatedreinforcingsteelinconcrete.GRJNST,Volume:04-Issue2(2026)/ISSNP:2790-7643ArticleID:2049https://doi.org/10.53762/grjnst.04.02.01