一種新的考慮界面特性的珊瑚骨料混凝土三維細(xì)觀建模方法（英文）

一種新的考慮界面特性的珊瑚骨料混凝土三維細(xì)觀建模方法（英文）ANovelThree-DimensionalMicroscopicModelingMethodforCoralAggregatesReinforcedConcretewithConsiderationofInterfaceCharacteristicsAbstract:Coralaggregatesarewidelyusedasacost-effectiveandeco-friendlyalternativetoconventionalaggregatesinconcreteproduction.However,theirheterogeneousstructureandpeculiarsurfacemorphologyposechallengestotheeffectivebondingbetweenaggregateandcementpaste,leadingtoreduceddurabilityandmechanicalpropertiesofconcrete.Tosolvethisproblem,acomprehensivethree-dimensionalmicroscopicmodelingmethodisproposedtoinvestigatetheinterfacecharacteristicsofcoralaggregatesreinforcedconcrete.Inthemodel,thevirtualaggregateiscomposedofahierarchicalstructureincludingtheskeleton,coraltissue,andsurfaceroughness,andthecementpasteisrepresentedbydiscreteelements.Thebondingbetweenaggregateandcementpasteisrealizedbytheintroductionofinterfaceelements,whichaccountfortheadhesiveforcesbetweenthetwomaterials.Thenumericalsimulationsdemonstratethattheproposedmodelcancapturethecomplexinteractionsbetweenaggregateandcementpasteandpredictthemechanicalpropertiesanddurabilityofcoralaggregatesreinforcedconcreteaccurately.Thefindingsprovideatheoreticalbasisfortheoptimizationofconcretemixdesignandthedevelopmentofnewtypesofcoralaggregatesreinforcedconcrete.1.IntroductionCoralaggregatesareatypeofmarinenaturalmaterialthathasreceivedincreasingattentioninconcreteproductioninrecentyearsduetotheiruniqueproperties,suchaslightweight,highvoidcontent,andgoodthermalinsulation(Chenetal.,2016).Besides,theuseofcoralaggregatescanreducetheecologicalimpactofquarryingandminingactivitiesonland-basedresources,benefitingthesustainabledevelopmentofconstructionindustry(TayehandIsmail,2014).However,theheterogeneityandirregularsurfacemorphologyofcoralaggregateshavehinderedtheirapplicationasaneffectivereinforcementinconcretestructures,mainlyduetotheweakadhesiveforcesbetweenaggregateandcementpaste(Xiaoetal.,2020).Thisresultsinreducedmechanicalstrength,durability,andservicelifeofconcretestructures.Theinterfacebetweenaggregateandcementpasteplaysacrucialroleindeterminingthepropertiesandperformanceofconcrete.Thebondingmechanismbetweenthetwomaterialsinvolvesmechanicalinterlocking,hydrationproducts,andchemicalreactions,amongothers.Thecorrelationbetweenthegeometricandsurfacepropertiesofaggregateandtheinterfacecharacteristicshasnotbeenfullyunderstood.Effectivemodelingoftheinterfacemechanismsisfundamentaltotheoptimizationofconcretemixdesignandthedevelopmentofnewtypesofaggregatesreinforcedconcrete.Duetotheuniquestructureandcomplexinteractionbetweenaggregateandcementpasteincoralaggregatesreinforcedconcrete,themicroscopiccharacteristicsoftheinterfaceareofgreatsignificance.Numericalsimulationmethods,suchasfiniteelementmethod(FEM)anddiscreteelementmethod(DEM),havebeenwidelyusedinthestudyofconcretemicrostructure,whichcanprovideeffectivemodelingofheterogeneousandanisotropicmaterials.Inthisstudy,acomprehensivethree-dimensionalmicroscopicmodelingmethodthatconsiderstheinterfacecharacteristicsofcoralaggregatesreinforcedconcreteisproposed.Theproposedmethodcancapturethecomplexinteractionsbetweenaggregateandcementpasteandinvestigatethemechanicalpropertiesanddurabilityofconcretestructures.2.ModelDevelopment2.1HierarchicalStructureofCoralAggregatesThehierarchicalstructureofcoralaggregatesconsistsoftheskeleton,coraltissue,andsurfaceroughness,asshowninFigure1.Theskeletonisthefundamentalstructuralelementofthecoralaggregate,whichdeterminesthemechanicalpropertiesofthematerial.Thecoraltissueprovidesadditionalsupportandprotectiontotheskeleton,andplaysaroleinthetransferofstressesbetweenskeletonandcementpaste.Thesurfaceroughnessofcoralaggregateaffectsthebondingbetweenaggregateandcementpaste,whichiscloselyrelatedtothedurabilityofconcretestructures.2.2DiscreteElementModelingofCementPasteThecementpasteisrepresentedbydiscreteelementsintheproposedmodel,whichcanprovideaneffectiverepresentationoftheheterogeneityandanisotropyofcementitiousmaterials.Thediscreteelementmethodisanumericalmethodbasedontheprincipleofparticlemechanics,whichcansimulatethebehaviorofindividualparticlesunderexternalloads.Inthemodel,thecementpasteparticlesareassumedtoberigidspheres,andthecontactbetweenparticlesisgovernedbytheHertziancontactlaw.Theinterparticlecohesionisrealizedbytheintroductionofcohesivecontactmodel.2.3InterfaceModelingbetweenAggregateandCementPasteTosimulatethecomplexinteractionsbetweenaggregateandcementpaste,theinterfacebetweenthetwomaterialsisintroducedinthemodel.Theinterfaceisrealizedbytheintroductionofinterfaceelements,whichaccountfortheadhesiveforcesbetweenaggregateandcementpaste.Theinterfacialbehaviorbetweenaggregateandcementpasteisdeterminedbythesurfaceroughnessandchemicalpropertiesofthetwomaterials.Theadhesiveforcesbetweenaggregateandcementpastearemodeledbythecohesivecontactmodel,whichconsidersthesurfaceroughnessandmicrostructureofthetwomaterials.3.ResultsandDiscussionTheproposedmodelisappliedtoinvestigatethemechanicalpropertiesanddurabilityofcoralaggregatereinforcedconcrete.Thenumericalsimulationsshowthatthemodelcancapturethecomplexinteractionsbetweencoralaggregateandcementpaste,andpredictthemechanicalpropertiesanddurabilityofcoralaggregatesreinforcedconcreteaccurately.Theinterfacebetweenaggregateandcementpasteplaysacrucialroleindeterminingtheperformanceofconcretestructures,andthesurfaceroughnessofcoralaggregatehasasignificantimpactonthebondingbetweenaggregateandcementpaste.4.ConclusionInthisstudy,acomprehensivethree-dimensionalmicroscopicmodelingmethodthatconsiderstheinterface