ASTM C1293-2008b 由于碱-硅反应引起的混凝土长度变化测定的标准试验方法

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【英文标准名称】:StandardTestMethodforDeterminationofLengthChangeofConcreteDuetoAlkali-SilicaReaction
【原文标准名称】:由于碱-硅反应引起的混凝土长度变化测定的标准试验方法
【标准号】:ASTMC1293-2008b
【标准状态】:现行
【国别】:美国
【发布日期】:2008
【实施或试行日期】:
【发布单位】:美国材料与试验协会(US-ASTM)
【起草单位】:C09.26
【标准类型】:(TestMethod)
【标准水平】:()
【中文主题词】:
【英文主题词】:aggregate;alkali-silicareactivity;concrete;lengthchange;pozzolan;slag;Aggregate(potentialalkalireactivity);Changeinlength;Concreteaggregates;Expansivealkali-silicareactivity;Silica
【摘要】:Alkali-silicareactionisachemicalinteractionbetweensomesiliceousconstituentsofconcreteaggregatesandhydroxylions(1).Theconcentrationofhydroxylionwithintheconcreteispredominantlycontrolledbytheconcentrationofsodiumandpotassium(2).Thistestmethodisintendedtoevaluatethepotentialofanaggregateorcombinationofanaggregatewithpozzolanorslagtoexpanddeleteriouslyduetoanyformofalkali-silicareactivity(3,4).Whentestinganaggregatewithpozzolanorslag,theresultsareusedtoestablishminimumamountsofthespecificpozzolanorslagneededtopreventdeleteriousexpansion.Pozzolanorslagfromaspecificsourcecanbetestedindividuallyorincombinationwithpozzolanorslagfromothersources.Whenselectingasampleordecidingonthenumberofsamplesfortest,itisimportanttorecognizethevariabilityinlithologyofmaterialfromagivensource,whetheradepositofsand,gravel,orarockformationofanyorigin.Forspecificadvice,seeGuideC295.Thistestmethodisintendedforevaluatingthebehaviorofaggregatesinportlandcementconcretewithanalkali(alkalimetaloxide)contentof5.25kg/m3orinconcretecontainingpozzolanorslagwithanalkalicontentproportionallyreducedfrom5.25kg/m3Na2Oequivalentbytheamountofpozzolanorslagreplacingportlandcement.Thistestmethodassessesthepotentialfordeleteriousexpansionofconcretecausedbyalkali-silicareaction,ofeithercoarseorfineaggregates,fromtestsperformedunderprescribedlaboratorycuringconditionsthatwillprobablydifferfromfieldconditions.Thus,actualfieldperformancewillnotbeduplicatedduetodifferencesinconcretealkalicontent,wettinganddrying,temperature,otherfactors,orcombinationsofthese(5).Resultsoftestsconductedonanaggregateasdescribedhereinshouldformapartofthebasisforadecisionastowhetherprecautionsshouldbetakenagainstexcessiveexpansionduetoalkali-silicareaction.Resultsoftestsconductedoncombinationsofanaggregatewithpozzolansorslagshouldformapartofthebasisforadecisionastowhetherthespecificpozzolanorslag,whenusedintheamounttested,waseffectiveinpreventingexcessiveexpansion.Thesedecisionsshouldbemadebeforeaparticularaggregateisusedinconcreteconstruction.CriteriatodeterminethepotentialdeleteriousnessofexpansionsmeasuredinthistestaregiveninAppendixX1.WhentheexpansionsinthistestmethodaregreaterthanthelimitshowninX1.2,theaggregateorcombinationofaggregatewiththetestedamountofpozzolanorslagispotentiallyalkali-reactive.Supplementalinformationshouldbedevelopedtoconfirmthattheexpansionisactuallyduetoalkali-silicareaction.PetrographicexaminationoftheconcreteprismsshouldbeconductedafterthetestusingPracticeC856toconfirmthatknownreactiveconstituentsarepresentandtoidentifytheproductsofalkali-silicareactivity.Confirmationofalkali-silicareactionisalsoderivedfromtheresultsofthetestmethodsthisproceduresupplements(seeAppendixX1).Ifthesupplementaltestsshowthatagivenaggregateispotentiallydeleteriouslyreactive,additionalstudiesmaybeappropriatetoevaluatepreventivemeasuresinordertoallowsafeuseoftheaggregate.PreventivemeasuresarementionedintheAppendixtoSpecificationC33.Thistestmethoddoesnotaddressthegeneralsuitabilityofpozzolansorslagforuseinconcrete.ThesematerialsshouldcomplywithSpecificationC618,SpecificationC989,orSpecificationC1240.