土木工程外文翻译混凝土施工裂缝原因及防治.docx

土木工程外文翻译混凝土施工裂缝原因及防治.docx

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土木工程外文翻译混凝土施工裂缝原因及防治

Constructioncracksinconcrete,causesandprevention

Constructioncracksofconcretereasonfortheexternalandinternal.Theinitialmainlyreferstotheinternaldefectsofconcreteinearlyconcrete,itsinternalhardeningprocesswillexistnumerousmicro-pores,air-pocketandmicrocracks,Externalreferstotheloadreason:

temperaturecrack,dryshrinkageeffectetc.Inthese,canproducevariousformsofconcretecracks.Tograsptheconstructionprocessofrawmaterials,inpouringprocessconfigurationofprogressandthickness,grasptimelymaintenanceworkwell,whichcanavoidconcretecracks.

A,Thecauseofthetear

1.Theinitialdefectsofconcrete

Concreteiscomposedofcement,sandaggregate,mixedwithwaterandothermaterialsandformationofheterogeneitybrittlematerials.Inthebeginning,becausehardenedconcreteconstructionanddeformation,aseriesofproblems,suchasconstraintintheconcreteshapesclerosiswillexistnumerousmicro-pores,air-pocketandmicrocracksofconcretethatusuallycalledinitialdefects.Microcracksisusuallyacracksintheconcrete,bearing,andsomeotherfunctionnotharm.Butunderload,temperatureofconcrete,shrinkageandfunction,microcrackswillbeexpandedandconnectivity,andfinallyformthevisiblecracksofconcrete,macroscopiccrack,saiditwastheuseofconcretestructure,propertiesanddurabilityofadverseeffects.

2.Theloadfactor

Duetothetensilestrengthofconcretestructureorstructures,smallasapartoftheexternaleffectsofstressthanconcretetensilestrength,willcrack.Therefore,theconcreteintheloadandtheload,canproduceacrack.Toloadthecrack,canproducebyreasonabledesignandconstructiontoprevent.Fortheloadofcrack,duetoreasons,itishardtohandleandprevent.Themorecommonthanloadfactorshavetemperature,dryshrinkage,settlingcontractiondeformation,plasticshrinkagedeformation,etc,inthesefunction,canmakeconcreteinsidetensilestress.

3.Bigvolumeconcretecrackformationreasons

Massiveconcretecrackingreasonscanbedividedintotwotypes:

oneisthestructuralcracks,iscausedbyexternalload,2itismaterialofcrackisnotcausedbythechangesofdeformationandtemperaturestressandismainlycomposedofconcrete'sshrinkage.Thisarticlemainlydiscussedtypematerials.Onespecificreasonsareasfollows:

Thetemperaturestresscausedbyfracture（temperaturecrack）temperaturecracksinthemainreasoniscausedbytemperaturedifference.Temperaturecanbedividedintothreetypes:

earlyconcretepouring,producelargeamountsofthehydrationheat,duetotheconcreteisapoorconductorofheataccumulationinconcrete,thehydrationheattosendout,oftenmakeinternaltemperaturesrise,concreteandreinforcedconcretesurfacetemperatureforoutdoorenvironmenttemperature,itisformed,thetemperatureandtemperatureinsideofcondensateinearlyconcretetensilestresswhenmorethanconcretecompressivestrength,willcausecrackinginconcrete,Inaddition,inthedismantlingformwork,surfacetemperatureandreducethetemperaturecausedbyfast,andwillcausecracking.Whentheconcretetemperature,maximumheatradiatestotheminimumtemperature,temperature,orusethemwiththehighesttemperaturedifferenceistheinternaltemperature,Thesethreetemperaturewillproducetemperaturecrack.Inthesethreetemperature,ismainlycausedbyhydrationheatandthetemperature.

Shrinkagecrackcontractiontherearemanycauses,includingdryingshrinkage,plasticshrinkage,shrinkage,carbonationcontraction,etc.Heremainlyintroducesdryingshrinkageandplasticshrinkage.

Afterdryingshrinkageofconcretesclerosis,indryenvironment,thewaterconcretetothelosscausedbyinsideextroversion,concretetheshrinkagedeformationcracks.

Theplasticshrinkageofcementandconcreteintheactivityofhighertemperature,orinlowwater-cementconditionexacerbatecausecraze.Whentheconcretesurfacewaterobviouslydecreased,lactationevaporationofwatercannotgetthetimelysupplements,thenconcreteisstillinastateofplastic,byaconcretesurfacetension,unevendistributionwillappearthecracksofconcretecracks,andfurtherintensifythemoistureinsidebody,andfurtherexpansioncrack

Second,themeasurestopreventcracks

Fromtheaboveanalysis,thecrackismainlycausedbytemperaturedifferenceandcontraction,soinordertopreventthecracksof,willmaximizereducetemperatureandreducetheshrinkageofconcrete,specificmeasuresasfollows.

1.Optimizingrawmaterials

（1）Cement.Thecementshouldbechosenaccordingtotheengineeringproperties,constructioncondition,climateandothertechnicalrequirements,comprehensiveconsideration,tomeetthestrengthanddurabilityofconcretedesignrequirements.Whenthechoiceshouldbelabeledwithcementconcretedesignmatchthelabel.Forfullstrengthofcement,cement,cementsavefromthelabelforconcretelabel1.5to2timesasappropriate.

（2）aggregate.（a）coarseaggregate.Thecoarseaggregateconcreterubbleisclose-grained,musthavetheenoughstrength,hardtoexpandthecoarseaggregatesize.Toensuretheconcretepouringdaoclose-grained,coarseaggregatemaximumdiameterlessthantheminimumsizeofthestructuralsections1/4,alsonotgreaterthantheminimumdistancebetweensteelnetforthickness3/4,in10centimetersandconcrete,allowingadoptsmaximumdiameter11/2oftheaggregatenumber,butitshallnotexceed25%.（b）fineaggregate.Sandparticlegradationoftechnicalpropertiesofconcreteinfluence,requeststheporosityandtotalsurfaceareasmall,smallneedtotalsurfaceonthesurfaceofthegravelpackagewillreducequantityofcementslurry,canreducethedosageofcementhydrationheat,reducetopreventcracks.Ontheotherhandistocontrolthehydraulicsand,thecontentof5%inconcrete,"thecontractiondeformation,thehydraulicandlargercrack,fineaggregatetousecleaninthesand.

（3）admixtures.（a）water-reducingagent.Jianshuijibelongstothesurfaceactivesubstances,isakindofcementdispersant.Itsmainfunctionofimprovingconcreteworkability,reducetheconsumptionofconcretemixture,reducewater-cementratioincreases,andimprovetheliquidityofconcretestrengthofconcreteorkeepinconcretecementstrengthmustdecrease,whilethewater-cementratio,thedosageofcementtopreventcrackingisreduced.（b）retarder.Retarderisdelayingtheroleofconcreteexothermicpeaktime,2itistoimproveworkability,andreducethelossofcollapsbillity.（c）air-entrainingagent.Intheapplicationofconcreteair-entrainingagentforimprovingtheconcreteworkability,canpump,improvingtheconcretedurabilityisveryfavorable.Inacertainextentincreaseanti-crackingperformanceofconcrete.

（4）massconcretechoosesrawmaterialsshouldpayattentiontothefollowing:

①Thecoarseaggregategradation,appropriateUSEScontinuousfineaggregateZhongShashouldbeadopted.

②AdmixturesappropriateUSESretarder,water-reducer,AdmixturesappropriateUSESflyash,slagpowderetc.

③Inmassconcretestrengthofconcreteandtheslumpandtherequirementsofthepremise,shouldimprovemixingandaggregatecontent,inordertoreducethedosageofcementconcretealone.

④Shouldtrytochoosecementhydrationheatlow,settingtimeislong,thecement,lowthermalPortlandcementslagsilicatecement,cement,slagdamPortlandcement,coalashPortlandcement,volcanicgrayPortlandcement,etc.

However,theslagcementhydrationheatlowwatercementratioofchromatographyinotherlarge,castinglotsofwatersurfacelayer.Thisphenomenonisnotonlyaffectlactationwater,alsoinfluencetheconstructionspeedandqualityofconstruction.Becausethewatergatheredinseparationbetweenthetwocastingconcretesurfacelayer,change,andwater-cementratiointhewaterandtookoutsomeofthemortar,thusformingalayerofinterliningcontent,destroyedthecohesiveforceofconcreteandholistic.Thesizeofthewaterconcretelactationwithwaterwater,water,lactation;Andwiththetemperature,waterseparationoftimewithtemperaturecompletelyandshortening,Inaddition,alsowiththecompositionandfinenessofcement.Therefore,inselectingslagcementshouldbechosenwhenthevarieties,andlactationshallbeaddingwater-reducingagentinconcrete,toreducetheconsumption.Duringconstruction,shouldbeinwaterormixingsometomographyuniformrollingcementcastinginwater,with3-degreesvibrationcompaction,continueagainafteraconcretecasting.

2.thereasonableconstructionmethod

（1）Theconcretemixingandtransportation.（a）white,accurategraspofconcreteproportion,especiallythestrictcontrolofwaterconsumption,thedeterminationofsand.Recordsofeveryblockwatercement,sandandgravel,specificquantity,theapplicationmustbeaccuratetoscale,bymixing.Goodcontrolofconcreteslumpandgeneralshouldsnotbetoobig,in120±20mm.Tominimizethemouth3concretetemperature.（b）concretemixinginastorehouseaftergoodtransportprocess,topreventtoproduceseparation,lactationwater,mortarlossshouldshortentransportationtime,concreteloadingnottoofull.

（2）Concretepouringandopenmode.Pouringprocessmaybeclose-grained,vibrationtovibrationtimeshouldbeuniforminsurfacefunctionalplasmaadvisable,uniformspacing,vibratingforcescopeaffectedoverlap1/2advisable,aftercasting,compaction,surfacemust,inordertopreventthesurfacecrack.Trytoavoidinthesolarradiation,hightimeduetotheneedsoftheprojectifpouringinsummerconstruction,avoidnoonpouringtemperatureperiod,trytoarrangeatn