HeatandmasstransfersinaconcretewallwithcompositelinerunderaccidentalconditionsOriginalResearchArticle

Theaimofthisworkwastostudythebehaviourofaconcretewall,coveredwithacompositelinerandexposedtoaccidentalconditionsleadingtohightemperaturesandpressuresonafaceofthematerial.Inthelaboratory,twopracticallevelsofaccidentalsituations(beyonddesign)havebeenconsidered.Firstly,the“SC1”scenario(accidentalconditions)consistedofarisefromambientconditionstoasaturationpointof160°C,andapressureof0.75MPain12h,usingthemaximumincreasepossiblewiththeapparatus.Thisrisewasthenfollowedbycooling,leadingto0.22MPaand120°Cin24h.Theseconditionsweremaintainedforseveraldays.Secondly,a“SC2”scenario(severeaccidentconditions)consistedofarisetoasaturationpointof173°Candapressureof1MPa,theseconditionsweremaintainedfor24hbeforecooling. Acylindricalspecimenof1.3mofthicknesswasused.Thermocouples,pressuretapsandmoisturegaugeswereimplementedbeforeconcreting.Thesedevicesprovidedlocalinformation,andweremostlydistributedinthefirst0.30moftheconcrete.Theconcretecomposition(highperformanceconcrete)wasthesameasthatusedfortheconstructionoftheCIVAUX2nuclearpowerstation. Typicalexperimentalresultsfortheevolutionoftemperature,pressureandwatercontentasfunctionsoftimeareshownforthetwotestconditions.Theconcreteattachedtothebackofthecompositedried,andamasstransferwasinducedtowardscolderzonesinthecentreofthespecimen.Thelineractedasaheatinsulatorandthepressureactingonthebackofthecompositeremainedlowerthanthatappliedonthecomposite.Theresidualadhesionofthelinertotheconcretewasmeasured.Finally,theoverallresultsallowedthecomparisonofsituationswherethewallwaslinedandunlined,duringexposuretoSC1andSC2conditions.