alternative method for concrete structures compressive strength estimation with small-scale destruction

ALTERNATIVEMETHODFORCONCRETESTRUCTURESCOMPRESSIVESTRENGTHESTIMATIONWITHSMALLSCALEDESTRUCTIONFEB2011,VOLUME5,NO2SERIALNO39,PP147153JOURNALOFCIVILENGINEERINGANDARCHITECTURE,ISSN19347359,USAAITERNATIVEMETHODFORCONCRETESTRUCTURESCOMPRESSIVESTRENGTHESTIMATIONWITHSMALLSCALEDESTRUCTIONACHFASZACOEBANDKOJIISHIBASHILDEPARTMENTCIVILENGINEERING,BRAWOAYAUNIVERSITYINDONESIA2DEPARTMENT0CIVILENGINEERINGSAGAUNIVERSITY,UAPAN茹KL辫HLN档ABSTRACTTOESTIMATEACOMPRESSIVESTRENGTHFROMEXISTINGCONCRETESTRUCTURESBYCOREDRILLINGAREUSUALLYGATHEREDWITHADIAMETERSPECIMENOFTO0MMORTHREETIMESOFMAXIMUMCOARSEAGGREGATESIZEANDEXAMINEDBYUNIAXIALCOMPRESSIVESTRENGTHUCSITISRELATIVELYDIFFICULTTOGATHERALARGESIZEDCORE,ANDAPITPLACEWILLBELIMITEDBYMAINMEMBERSTOGETANALTERNATIVESOLUTIONWITHSMALLERSPECIMENPOINTLOADTESTPLTHASBEENSELETEDWHICHISASIMPLETESTANDWIDELYACCEPTEDINROCKMATERIALSRESEARCH,BUTRELATIVELYNEWINCONCRETETHERELIABILITYOFPLTISE,|ALUATEDBYEXTRACTINGAIOTOFCOREDRILLEDSPECIMENFROMREADYMIXEDCONCRETEBLOCKSWITHMAXIMUMCOARSEAGGREGATESIZE,GMOF20MMINREPRESENTATIVEOFARCHITECTURAISTRUCTURESAND40MMINREPRESENTATIVEOFCIVILSTRUCTURESONTHERANGEOFCONCRETEGRADEFROM16TO50COMPRESSIVESTRENGTHSWERECLASSIFIEDINTOGENERALCATEGORIES,CONVERSIONFACTORSWCRCDETERMINEDANDSCATTERINGCHARACTERISTICSWEREALSOINVESTIGATEDTHERELATIONSHIPBETWEENPOINTLOADINDEX/SANDCOMPRESSIVESTRENGTHOFCONCRETECORESPECIMENFFCCANBEWRITTENASLINEARAPPROXIMATIONASJCCK/SCKEYWORDSSTRENGTHESTIMATION,SMALLCORE,POINTLOADINDEX,LINEARAPPROXIMATION1INTRODUCTIONONEOFTHERELIABLETESTSFORASSESSINGINSITUSTRENGTHOFCONCRETEISCORINGITMAYPROVEASEXPENSNETESTANDTHEBOREHOLESTHATHAVETOBERESTORED,BUTTHERESULTINGDATAAREUSUALLYACCEPTEDASTHEBESTEVIDENCEOFTHECONDITIONOFCONCRETEINPLACEITISESTABLISHEDTHATACOREDRILLEDSPECIMENDIAMETEROF100MMORTHREETIMESOFMAXIMUMCOARSEAGGREGATESIZEFROMACONCRETESTRUCTUREMEMBERSHOULDBETAKENFORPERFORMINGSTRENGTHEVALUATION1】SMALLCORESAREOFTENUSEDASSUBSTITUTESFORLARGECORESTOTESTCONCRETESTRENGTHTHEYHAVETHEADVANTAGESOFBEINGEASILYDRILLEDANDCUT,MINIMUMDAMAGETOSTRUCTURES,ANDALOWERCAPACITYMACHINEISNEEDED2THEMAINPARAMETERFORCHARACTERIZINGACONCRETEINCORRESPONDINGAUTHORACHFASZACOEB,DRENG,ASSISTANTPROFESSOR,RESEARCHFIELDSSTRUCTURALANDCONCRETEENGINEERINGEMAILZACOEB_AYAHOOCORNENGINEERINGPRACTICEISCOMPRESSIVESTRENGTHTHEMAXIMUMAGGREGATESIZEISCONSIDERABLEASPLAYEDROLEFORAFFECTINGTHEPROPERTIESOFCONCRETE,INCLUDINGCOMPRESSIVESTRENGTH3THESTANDARDLABORATORYTESTUSUALLYREQUIRESASTANDARDSPECIMENS,SOINDIRECTTESTARENEEDEDTOBEDEVELOPEDTHEPLTISINTENDEDASANINDEXTESTFORTHESTRENGTHCLASSIFICATIONOFROCKMATERIALS,BUTITMAYALSOBEWIDELYUSEDTOPREDICTOTHERMATERIALSTRENGTHPARAMETERITISANATTRACTIVEALTERNATIVEMETHOD,BECAUSEITCANPROVIDESIMILARDATAATALOWERCOST,ASIMPLEPREPARATIONOFSPECIMEN,ANDPOSSIBILITYONFIELDAPPLICATIONINDEXTOSTRENGTHCONVERSIONFACTORSAREDEVELOPEDINORDERTOESTIMATEUCSINDIRECTLY4】MANYRESEARCHWORKSHADBEENCONDUCTEDTOACKNOWLEDGEWITHREGARDTOPLTANDRESULTEDINWIDELYUSEDANDOTHERPARAMETERS57HOWEVER,MOREEXPERIMENTALWORKSHELPSTOSUBSTANTIATETHEEXISTINGCORRELATIONL48ALTERNATIVEMETHODFORCONCRETESTRUCTURESCOMPRESSIVESTRENGTHESTIMATIONWITHSMALLSCALEDESTRUCTION2THEORETICALBACKGROUNDASIMPLEFORMULAISSTARTEDBYTAKINGANIDEALIZEDFAILUREPLANEOFDIAMETRICCORESAMPLEASSHOWNINFIG18FROMTHISFIGURECANBETAKENINTOACCOUNTASCONCEPTUALMODELFORDERIVATIONONPOINTLOADINDEXEQUATIONAS1WHERE,/SPOINTLOADINDEXMPAPLOADNDDIAMETEROFSPECIMENFMMBYTAKINGTHECIRCULARAREAOFTHECOREINTOACCOUNT,ANARGUMENTCANBEMADETHATEQ1SHOULDBEWRITTENAS2THEUSEROFTHISTESTSOONNOTICEDTHATTHERESULTSOFADIAMETRICTESTWEREABOUT30HIGHERTHANTHOSEFORANAXIALTESTUSINGTHESAMESPECIMENDIMENSIONSTHISDIFFERENCEISSUGGESTEDACKNOWLEDGEBYAPPLYINGASIZECORRECTIONANDINTRODUCINGTHEEQUIVALENTCOREDIAMETEROFDE4,8】HENCE,THEEQ2CANBEREWRITTENAS寺THEVARIATIONSOFISWITHSPECIMENSIZEANDSHAPELCADTOINTRODUCEAREFERENCEINDEX/S0JWHICHCORRESPONDSTOTHEISOFADIAMETRICALLYLOADEDROCKCOREOF50MMDIAMETER8ACCORDINGLY,INITIAL厶VALUESAREREDUCEDTOISF5OBYSIZECORRECTIONFACTORSLOADINGDIRECTIONFIG1SPECIMENDIAMETRICOFPLTOBCORESETHATHADBEENDETERMINEDFROMEMPIRICALCURVESASAFUNCTIONOFDITISINDICATEDTHATTHECONSIDERABLYLARGERSHAPEEFFECTSHOULDBEAVOIDEDBYTESTINGSPECIMENSWITHSPECIFIEDGEOMETRIESANEWCORRECTIONFUNCTIONWHICHACCOUNTSFORBOTHSIZEANDSHAPEEFFECTSISPROPOSEDBYUTILIZINGTHECONCEPTOFEQUIVALENTCOREDIAMETER【4THISFUNCTION,KNOWNASGEOMETRICCORRECTIONFACTORFISGIVENBY1R5F/S4WHERE,FTHEGEOMETRICCORRECTIONFACTORTHEUNIQUEPOINTLOADINDEXCANBEOBTAINEDBYAPPLYINGASIZECORRECTIONFORTHESPECIMENASPOINTLOADINDEXOF/SVARIESWITHCORESPECIMENDIAMETEROFDETHESIZECORRECTEDPOINTLOADINDEXOFISR5OFOREACHSPECIMENISDEFINEDASTHEVALUEOFISTHATWOULDHAVEBEENMEASUREDONASTANDARDSPECIMENDIAMETEROFD50MMINTHECASEOFSPECIMENDIAMETEROFDOTHERTHAN50MM,SIZECORRECTIONMUSTBECALCULATEDBYUSINGOFEQ53LABORATORYWORKSTHECONCRETEBLOCKFORCORESPECIMENEXTRACTINGWERESIZEDOF300MMX300MM600MMMADEFROMREADYMIXEDNORMALCONCRETEWITHTYPICALSLUMPRANGEVALUEFROM8TOL2CMFORMOSTAPPLICATIONASWORKABILITYCONTROLANDDIVIDEDINTOTWOGROUPSASSHOWNINTABLE1FORCURINGALLCONCRETEBLOCKSPECIMENSWERECOVEREDWITHPLASTICSHEETSANDTHEHUMIDITYWASSETFORABOUTAWEEKCOMMONLYINJAPAN,FORARCHITECTURA1STRUCTURESSUCHASBUILDINGCONSTRUCTIONISUSINGTHEMAXIMUMCOARSEAGGREGATESIZE,GM0F20MMWHILEFORCIVILSTRUCTURESSUCHASPIER,ABUTMENT,BRIDGEDECKANDCHECKDAMISUSINGTHEMAXIMUMCOARSEAGGREGATESIZE,GMOF40MMCORESPECIMENDIAMETEROF10050AND35MMWEREEXTRACTEDFROMTHEABOVEMENTIONEDCONCRETEBLOCKWITHTHEELECTRICCOREPULLINGOUTMACHINETHEWETTYPEBYFLOWINGSOMEWATERDURINGTHECOREALTERNATIVEMETHODFORCONCRETESTRUCTURESCOMPRESSIVESTRENGTHESTIMATIONWITHSMAL1SCALEDESTRUCTIONTABLE1GROUPOFCONCRETEBLOCKDRILLEDPROCESSISAPPLIEDTHEDIRECTIONOFEXERACTIONISCONSIDEREDASTHEDIRECTIONOFCONCRETEPLACINGASVERTICALDIRECTIONINASSUMPTIONOFPRACTICALWORKINCONSTRUCTIONTHESITUATIONOFCORESPECIMENEXTRACTIONISSHOWNINFIG2THECORESPECIMENWITHH/DRATIOOF15AND20WERESELECTEDASCORESPECIMENOFPLTINTHISSTUDYINORDERTOESTABLISHASPECIFICH/DRATIO,CORESPECIMENSWERECUTBOTHENDSWITHACONCRETECUTTINGTABLE2TOTALNUMBEROFCORESPECIMENS149FIG2CORESPECIMENEXTRACTIONSMACHINETOBECOMEAFIXEDHEIGHTHTHETOTALNUMBERCOLLECTIONOFEACHSPECIMENISSHOWNINTABLE2THESPECIMENINPLTISTAKENANDLOADEDBETWEENTWOHARDENEDSTEELCONESTHESYSTEMCONSISTSOFASMALLHYDRAULICPUMP,AHYDRAULICJACK,APRESSUREGAUGEANDINTERCHANGEABLETESTINGFLAMEOFVERYHIGHTRANSVERSESTIFFNESSSPHERICALLYTRUNCATED,CONICALPLATENSOFTHESTANDARDGEOMETRYSHOWNINFIG3AREGROUPGRADEDMMH/D10TA1GROUPGFADEDMMH/DTBTAL15L3515L26353520L3520L26L6L615L051585505020992O87159015L54353520902OL382L2L15601582505020602079L1566151L33535206620L13I2424L559158750502058208615L2315L5735352O12620L72363015L1L15LL3505020LO820L081567352066501573502072L50ALTERNATIVEMETHODFORCONCRETESTRUCTURESCOMPRESSIVESTRENGTHESTIMATIONWITHSMALLSCALEDESTRUCTIONTOBEUSEDWITHTHECYLINDERAREAOF1452CMTHEPLATENSSHOULDBEOFHARDMATERIALSUCHASTUNGSTENCARBIDEORHARDENEDSTEELSOTHATTHEYREMAINUNDAMAGEDDURINGTEST4THECORESPECIMENINTHISSTUDYISGRADUALLYLOADEDBYACTIVATINGTHEHANDPUMPUNTILFAILUREANDDETERMINEDTHISLOADASPTHEPOINTLOADINDEXOFISWASCALCULATEDBYUSINGEQ3ANDFORCORESPECIMENDIAMETEROF35MMWASCORRECTEDTOTHESTANDARDCOREDIAMETERASPOINTLOADINDEXOF/SRS0FORCORESPECIMENDIAMETEROF50MMBYUSINGEQ4THEEXAMINATIONISCONDUCTEDBYUSINGPLTMACHINEWITHOILPRESSURECYLINDERTYPEANDMAXIMUMLOADCAPACITYOF98KNASSHOWNINFIG4FIG3POINTLOADCONEPLATENFIG4SETUPOFPLT4RESULTSANDDISCUSSION4COMPRESSIVESTRENGTHFROMACONCRETEBLOCKISEXTRACTEDACORESPECIMENWITHDIAMETEROF100MMASMINIMUMREQUIREMENTAND125MMASTHREETIMESOFMAXIMUMCOARSEAGGREGATESIZE1】,CUTBOTHENDSOFTHECOREWITHACONCRETECUTTINGMACHINE,ENDFACEPOLISHED,PROCESSEDITTOBECOMESPECIFICHMOF20ANDEXAMINEDBVUCSTESTTHEMEANVALUEOFCOMPRESSIVESTRENGTHOFCONCRETECORE,FCCISSHOWNINTABLE3,ANDASSUMEDTHESEVALUESASREFERENCEONTHISSTUDY42POINTLOADINDEXTHEMEANVALUESOFLSWERECOMPUTEDFORBOTHDIAMETERSIZESASSHOWNINTABLE4SCATTERINGCHARACTERISTICSWEREALSOINVESTIGATEDBYMENTIONINGOFCVCOEFFICIENTOFVARIATIONTHECVISTHEDEGREETOWHICHASETOFDATAPOINTSVARIESWHENASSESSINGPRECISION,THELOWEROFCVPERCENTAGE,THEBETTEROFPRECISIONBETWEENREPLICATESFORGROUPI,THELEVELOFCVISALMOSTSAMEORLESSTHANTHATONACTUALITYOFREADYMIXEDCONCRETEPRODUCTFROM10TO159ITCANBESTATEDTHATTHETESTRESULTSARESATISFYENOUGHFORGROUPII,THECVISBIGGERTHANTHEREQUIREMENTSEXCEPTFORCONCRETEGRADEOF30FORGROUPI,THELEVELOFCVFORH/DOF15ISSMALLERTHANH/DOF20ITCANBESTATEDTHATH/DRATIOOF15ISBERERTHANH/DOF20FORMAKINGAPLTTABLE3COMPRESSIVESTRENGTHALTERNATIVEMETHODFORCONCRETESTRUCTURESCOMPRESSIVESTRENGTHESTIMATIONWITHSMAL1SCALEDESTRUCTIONTABLE4POINTIOADINDEX15LCVICGROUPGRADEDMMH/DLSMPAGROUPGRADEDMMH/DF1MPAF15227L143515220261352O2I32L3I32O23O319L6L615187L075015185L875020193LO_82O195L8115324I143515252230352033LL24202552432L2L152579750L5212210502026L12020OL80II153212435152902633520328】312029227024241527L81501523LL825020277932O243L8215361L193515280247352O369L35202851973630L5306L045015243855020302L092024776153958135204059650153278_2502033489SPECIMENSFROMCOREDRILLEDEXTRACTIONWHILEFORCORESPECIMENDIAMETER,DISBETTERUSING50MMTHAN35MMBECAUSETHELEVELOFCVISALSOSMALLERBESIDETHISREASON,ITISALSOFULFILLEDWITHTHESTANDARDCOREDIAMETERREQUIREMENTSOF50MMFORALLGROUPS,ITISPOSSIBLEANDACCEPTABLEFORUSINGACOREDIAMETEROF50MMANDH/DRATIOOF20ASPLTSPECIMENWITHRESULTSINTHERANGEOFCVFROM8TO18APPLICATIONOFPLTFORSMALLDIAMETEROFCORESPECIMENISNOTSUGGESTEDFORD/GLARATIOBELOW125,CONSIDERINGTHECVRESULTSFORGLMOF40MMANDDOF35MMARELARGERTHAN2043CORRELATIONBETWEENPOINTLOADINDEXANDCOMPRESSIVESTRENGTHPOINTLOADINDEXOFCORESPECIMENDIAMETEROF50MM,ISISDETERMINEDASSTANDARDVALUEHENCE,THEVALUEOFDIFFERENTCORESPECIMENDIAMETER,IS3SSHOULDBECORRECTEDINORDERTOSHOWARELATIONSHIPWITHIS5OJBYUSINGEQUATION4AND5BYCORRECTINGTHEPOINTLOADINDEXOFISF35IANDASSUMINGASSTANDARDCORESPECIMENDIAMETEROF50MM,WILLADDTHENUMBEROFDATAFORANALYSISOFPOINTLOADINDEXISTHENEWRESULTFORTHISCOMBINATIONISSHOWNINTABLE5CORRESPONDINGWITHTHECOMPRESSIVESTRENGTHOFCONCRETECOREFCCFOREACHGRADETABLE5POINTLOADINDEXANDCOMPRESSIVESTRENGTHL52ALTERNATIVEMETHODFORCONCRETESTRUCTURESCOMPRESSIVESTRENGTHESTIMATIONWITHSMAL1SCALEDESTRUCTIONTHECORRELATIONBETWEENPOINTLOADINDEX,/S50ANDCOMPRESSIVESTRENGTHOFCONCRETECORE,FCCFORBOTHOFGROUPSISSHOWNGRAPHICALLYINFIGURE5AND6ITISCLEARLYEVIDENTTOSHOWTHECORRELATIONBYPROPOSINGASECONDORDEROFPOLYNOMIALANDLINEARREGRESSION,RESPECTIVELYITISPROVENBYSHOWINGTHESQUAREVALUEOFCORRELATIONCOEFFICIENTWHICHJUDGESTHEEFFECTIVENESSOFASECONDORDEROFPOLYNOMIALAPPROXIMATIONCURVEFORH/D15ISTHOUGHTTOBESIMILARFORH/D20LINIERREGRESSIONALSOSHOWEDTHESAMETRENDOFEFFECTIVENESSEXCEPTFORGROUPIITHERANGEOFREADYMIXEDCONCRETECOMPRESSIVESTRENGTHINFIELDAPPLICATIONISFROM18TO45MPA10】HENCE,THEAPPLICATIONOFPLTFORESTIMATINGINSITUSTRENGTHOFCONCRETESTRUCTURESHOULDBECONFIRMEDIN55SO454035302520151050THISRANGESO,THECORRELATIONWASLIMITEDTOTHISRANGEFORCORESPECIMENDIAMETEROF35AND50MMASSHOWNINFIG7WHENUSINGTHELINEARREGRESSIONASSHOWNINFIG6,THEAPPROXIMATIONLINEDOESNOTINTERCEPTINTHEORIGINPOINTHOWEVER,FIG7SHOWNTHATTHEFITTEDCURVEWILLPASSTHROUGHTHEORIGINWHICHAIMSTOESTABLISHTHERELATIONOFTHEWHOLEAREAWOULDBEOVERESTIMATEDITISPREFERABLETOUSINGLINEARAPPROXIMATIONTHANOTHERMODESINORDERTOMINIMIZETHESTANDARDFORTHEASSESSMENTOFRISKINCONCERNWITHTHESTANDARDCOMPRESSIVESTRENGTHTHATUSEDASLINEARAPPROXIMATIONFORINDEXTOSTRENGTHCONVERSIONFACTORKISSHOWNINFIG7THEKVALUEISCALCULATEDBYDIVIDEDTHECOMPRESSIVESTRENGTHFCWITHPOINTLOADINDEXWHILECISCONSTANTDEPENDONTHELINEARREGRESSIONEQUATIONO051152253354ISSOMPAFIG5SECONDORDEROFPOLYNOMIALREGRESSION55504540353O25201510500O00501O01502O02503O0FIG6LINEARREGRESSION3504O0IS5O,MPA富5董4540353025201510501ALTERNATIVEMETHODFORCONCRETESTRUCTURESCOMPRESSIVESTRENGTHESTIMATIOR,WITHSMALLSCALEDESTRUCTION3015017019021O23025O27029031O33035O370390LS5OFMPAFIG7LINEARAPPROXIMATIONFORLS50TOFC5CONCLUSIONITCANBECONCLUDEDTHATANAPPROXIMATIONCURVESHOWEDASTRONGCORRELATIONBETWEENPOINTLOADINDEXANDCOMPRESSIVESTRENGTH,RCFORCOREDIAMETEROF35AND50MMWITHHEIGHTANDDIAMETERRATIOOFH/D15AND20INADDITION,FORREFERENCENDEXISOL,ITCANBEAPPROACHEDBYLINEARREGRESSIONTOESTIMATEACONCRETESTRENGTHCANBECONDUCTEDWITHPROPOSEDEQUATIONASF七/SCTHEREISAPROSPECTTHATPLTCANBEAPPLIEDASINDIRECTMETHODTOESTIMATEACOMPRESSIVESTRENGTHONCONCRETESTRUCTUREAPPLICATIONOFPLTFORINSITUCONCRETECOMPRESSIVESTRENGTHESTIMATIONSHOULDBECONFIRMEDINTHERANGEOFCOMPRESSIVESTRENGTHFROM18TO45MPACONSIDERINGTHEMAXIMUMCOARSEAGGREGATESIZEOFGLHINCONCRETE,NEWCRITERIONISPROPOSEDBYDETERMININGTHEMINIMUMVALUEOFD/GMRATIOSHOULDNOTLESSTHAN125ACKNOWLEDGMENTSTHEFIRSTAUTHORISGRATEFULLYAPP