AnalyticalmodelfortimetocovercrackinginRCstructuresduetorebarcorrosionOriginalResearchArticle

Thestructuraldegradationofconcretestructuresduetoreinforcementcorrosionisamajorworldwideproblem.Reinforcementcorrosioncausesavolumeincreaseduetotheoxidationofmetalliciron,whichismainlyresponsibleforexertingtheexpansiveradialpressureatthesteel–concreteinterfaceanddevelopmentofhooptensilestressesinthesurroundingconcrete.Crackingoccurs,oncethemaximumhooptensilestressexceedsthetensilestrengthoftheconcrete.Thecrackingbeginsatthesteel–concreteinterfaceandpropagatesoutwardsandeventuallyresultsinthethoroughcrackingofthecoverconcreteandthiswouldindicatethelossofservicelifeforthecorrosionaffectedstructures.Ananalyticalmodelisproposedtopredictthetimerequiredforcovercrackingandtheweightlossofreinforcingbarincorrosionaffectedreinforcedconcretestructures.Themodellingaspectsoftheresidualstrengthofcrackedconcreteandthestiffnesscontributionfromthecombinationofreinforcementandexpansivecorrosionproductshavealsobeenincorporatedinthemodel.Theproblemismodeledasaboundaryvalueproblemandthegoverningequationsareexpressedintermsoftheradialdisplacement.Theanalyticalsolutionsarepresentedconsideringasimpletwo-zonemodelforthecoverconcrete,viz.crackedoruncracked.Reasonableestimationofthevariousparametersinthemodelrelatedtothecompositionandpropertiesofexpansivecorrosionproductsbasedontheavailablepublishedexperimentaldatahasalsobeendiscussed.Theperformanceoftheproposedcorrosioncrackingmodelistheninvestigatedthroughitsabilitytoreproduceavailableexperimentaltrends.Reasonablygoodagreementbetweenexperimentalresultsandtheanalyticalpredictionshasbeenobtained.Ithasalsobeenfoundthattensilestrengthandinitialtangentmodulusofcoverconcrete,annualmeancorrosionrateandmodulusofelasticityofreinforcementpluscorrosionproductscombinedsignificantlyinfluencepredictedtimetocovercracking.Theanalyticalpredictionsoftheproposedmodelhavealsobeenfoundtobeinlinewiththoseoftheotherreportedpublisheddata.