ASTM C457/C457M-2010a 硬化混凝土中的空腔系统的参数的显微镜检验的标准试验方法

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【英文标准名称】:StandardTestMethodforMicroscopicalDeterminationofParametersoftheAir-VoidSysteminHardenedConcrete
【原文标准名称】:硬化混凝土中的空腔系统的参数的显微镜检验的标准试验方法
【标准号】:ASTMC457/C457M-2010a
【标准状态】:现行
【国别】:美国
【发布日期】:2010
【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】:C09.65
【标准类型】:(TestMethod)
【标准水平】:()
【中文主题词】:
【英文主题词】:aircontent;airvoidparametersofhardenedconcrete;area-preparedsurfacerequired;averagechord-lengthofvoids;determinationofair-voidparameters;entrainedvoid;entrappedvoid;gritsforlappinghardenedconcrete;indexpoint;lapping;lengtho
【摘要】:Theparametersoftheair-voidsystemofhardenedconcretedeterminedbytheproceduresdescribedinthistestmethodarerelatedtothesusceptibilityofthecementpasteportionoftheconcretetodamagebyfreezingandthawing.Hence,thistestmethodcanbeusedtodevelopdatatoestimatethelikelihoodofdamageduetocyclicfreezingandthawingortoexplainwhyithasoccurred.Thetestmethodcanalsobeusedasanadjuncttothedevelopmentofproductsorproceduresintendedtoenhancetheresistanceofconcretetocyclicfreezingandthawing(1).Valuesforparametersoftheair-voidsystemcanbeobtainedbyeitheroftheproceduresdescribedinthistestmethod.Noprovisionismadefordistinguishingamongentrappedairvoids,entrainedairvoids,andwatervoids.Anysuchdistinctionisarbitrary,becausethevarioustypesofvoidsintergradeinsize,shape,andothercharacteristics.Reportsthatdomakesuchadistinctiontypicallydefineentrappedairvoidsasbeinglargerthan1mminatleastonedimensionbeingirregularinshape,orboth.Thehoney-combingthatisaconsequenceofthefailuretocompacttheconcreteproperlyisonetypeofentrappedairvoid(9,10).Watervoidsarecavitiesthatwerefilledwithwateratthetimeofsettingoftheconcrete.Theyaresignificantonlyinmixturesthatcontainedexcessivemixingwaterorinwhichpronouncedbleedingandsettlementoccurred.Theyaremostcommonbeneathhorizontalreinforcingbars,piecesofcoarseaggregateandaschannelwaysalongtheirsides.Theyoccuralsoimmediatelybelowsurfacesthatwerecompactedbyfinishingoperationsbeforethecompletionofbleeding.Applicationofthepaste-airratioprocedureisnecessarywhentheconcreteincludeslargenominalmaximumsizeaggregate,suchas50mm[2in.]ormore.Preparedsectionsofsuchconcreteshouldincludeamaximumofthemortarfraction,soastoincreasethenumberofcountsonairvoidsortraverseacrossthem.Theratioofthevolumeofaggregatetothevolumeofpasteintheoriginalmixmustbeaccuratelyknownorestimatedtopermitthecalculationoftheair-voidsystemsparametersfromthemicroscopicallydeterminedpaste-airratio.Note18212;Theair-voidcontentdeterminedinaccordancewiththistestmethodusuallyagreescloselywiththevaluedeterminedonthefreshconcreteinaccordancewithTestMethodsC138/C138M,C173/C173M,orC231(11).However,significantdifferencesmaybeobservedifthesampleoffreshconcreteisconsolidatedtoadifferentdegreethanthesamplelaterexaminedmicroscopically.Forconcretewitharelativelyhighaircontent(usuallyover7.5%),thevaluedeterminedmicroscopicallymaybehigherbyoneormorepercentagepointsthanthatdeterminedbyTestMethodC231.1.1Thistestmethoddescribesproceduresformicroscopicaldeterminationsoftheaircontentofhardenedconcreteandofthespecificsurface,voidfrequency,spacingfactor,andpaste-airratiooftheair-voidsysteminhardenedconcrete(1).Twoproceduresaredescribed:1.1.1ProcedureA,thelinear-traversemethod(2,3).1.1.2ProcedureB,t......
【中国标准分类号】:Q13
【国际标准分类号】:91_100_30
【页数】:15P.;A4
【正文语种】:英语