混凝土楼板开裂原因及处理方法Causes and treatment methods of con.docx
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混凝土楼板开裂原因及处理方法Causesandtreatmentmethodsofcon
混凝土楼板开裂原因及处理方法(Causesandtreatmentmethodsofconcretefloorcracking)
Causesofcrackingofconcretefloorslabandprocessingmethod
Residentialprojectscurrentlyfilledconcretefloorandwallcracksaremorecommon,accordingtotherelevantmaterialsandcombiningthesituationofmycompany,analysisofthecausesandCountermeasuresofcast-in-placeconcretefloorandmasonrywallcracksareasfollows,forreferenceinthework.
Thetypesofcracksintheconcretefloor,thecast-in-place
1.longitudinalcracks:
cracksalongthelongitudinaldirectionofthebuilding,thereareintheleather,downthroughtheindividual.
2.:
thetransversecracksinthespanrangeof1/3,thecracksalongthebuildingtransversedirection,thereareintheleather,downthroughtheindividual.
The3.cornercracksintheinclinedcracksappearfourcorneroftheroom,inthemajorityofepithelial.
4.irregularcrack:
crackdistributionanddirectionareirregular.
5.floor:
therootoftransversecracksfromcrackbearingin30cm,locatedintheepithelium.
6.embeddedalongthecrackdirectionofthewirepipe.
Causesofcracksinthefloor,two
1.design
1.1structuredesignsafetyreserveisrelativelysmall,insufficientreinforcementorsmallersection,thebeamformingpoorrigidity,theoveralldeflection,causedbythefourcornersoftheboardcrack.
1.2designofplatethicknessisnotenough,nordothedeflection,theoveralldeflection,causedbythefourcornersoftheboardcrack.
The1.3houseislongnotsetexpansionjoints,cracksintheweaklink.(AmericanConcreteInstitutedatasuggestthatconcreteshrinkageandtemperaturedeformationoftwokindsofdryshrinkagedeformationofeach30.48mabout19mm.shrinkagecausedbythechangeoftemperatureis37DEGC,thetemperaturechangeofeach30.48mcontractionorextensionof19mm.Somepeoplethinklongitudinalcontraction40mlongfloorduetohardeningandfreezingwas8-20mm.)
1.4basicdesignimpropertreatmentcausedbyunevensettlement,sothestructuretogenerateadditionalstress,resultinginfloorcracks.
The1.5floortwo-wayforcebyone-wayslabreinforcement,causingcracks.
2.reasonsforcommercialconcrete
2.1watercementratio,cementcontent.
2.2highperformanceretarderdosageistoolarge,notinthesolidificationfrontstonesink,producedheavycrack,oftenoccurinthebeamplatejunction.
2.3gravelgradationqualityisnotgood,notgood,largeamountofmud,containinglargeamountofpowder.
3,construction
3.1maintenanceisnotinplace,themandatoryrequirementsofconcretecuringtocoverandwater,nowmostdonotcover,wateringcannotguaranteeoftenmoist.
3.2theconstructionspeed,bearingonearly,especiallybrickresidentialfloor,thedaybeforepouringfloor,seconddaysonthebrick,takethecar,resultinginearlyconcretedamage.
3.3duringthecoldwinter.
3.4orearlyformremovalofformworksupportsystemstiffnessisnotenough.
3.5concretesurfacelaitancethickness,surfacestrengthisnotenough.
3.6duringtheconstructionofconcreteslabreinforcementcoverissteppedonbending,steppeddown,theprotectivelayeristoothick,thedecreaseofbearingcapacity.
Three,topreventtheconcretefloorcrackingmeasures
1.design
1.1intheuseofsmalldiametersteelcase,appropriatelyincreasingthereinforcementratio,theultimatetensilestrainofconcretecanbeimproved.
The1.2cornersofthenegativereinforcementtwo-wayconfiguration,
Unidirectionalplateisalsosurroundedbyboththeconfigurationofnegativereinforcement.
1.3inthesamereinforcementrate,reinforcedwithsmallerdiameter,reducingreinforcementspacing,canimprovethecrackresistanceofcast-in-placeslab.
2.construction
2.1cast-in-placefloortrytosetexpansionjoints,longitudinallengthofexpansionjointspacingofabout14mordesirableresidentialbuildingaunit,locatedintheslab,widthof10mm,themiddleofthesoftmaterials,andcontinuouslyreinforcedconcretebreak.
2.2steelbindingtoensureuniformspacing,ensurethenegativereinforcementpositionunchanged,pouringconcretesetMaRoad,notonthenegativereinforcement.
2.3usingtheplatevibrator,twopressingactivity,secondtimeswipingpressureinthefinalsetting.
2.4inthepreburiedwirepipewithsteelmesh,embeddedpipeasfaraspossiblealongthearrangementdirectionofreinforcementforce.
2.5byusingthemethodofcoveringandwateringmaintenance,coverageandwateringismandatoryrequirements,weareonlywatering,nocover,waterafterdryingcannotguaranteethetimelysupplement,themaintenanceperiodcannotguaranteecontinuousconcreteinwetstate,notuptotheeffectofmaintenanceshouldbe.
2.6concreteupto1.2MPanot,butearlydismantling,orbyearlyremovingsystem,keeptheverticalsupportafterstripping.
3,mixingstation
3.1toensuretheslumpofproductiondesign,tothescenefoundsegregationtotwomixing.
3.2toensurethequalityofcementandsand,ensurethescientificandreasonablemix.
3.3SRAwillsoonbeavailable,reducingagentinconcretemixingcanreduceshrinkagecracks.
Four,concretefloorcracks
4.1crackwidthlessthan0.3mmwith6202cementclosed.
4.2crackwidthisgreaterthan0.3mmbychemicalgrouting,thepracticeisasfollows:
(1):
chiselchiselseamalongthecrack,crackcutaccordingtothewidthanddepthof15~20mmVslot.
(2):
embeddedgroutingpipealongthecrackdirectionevery50cmdrillingaburiedgroutingnozzle,fixedbyglue.
(3):
aclosedfracturestructureadhesiverepeatedlyscraped,andclosedaroundthecrackandcrackbranching.
(4)airpressuretest:
fillsealleakagesite.
(5):
InjectionGroutinggroutinggroutingliquidpreparedbyaircompressor,0.2MPapressuregrouting,groutingmouthfromoneend,generallyfromtheadjacentGroutinggroutingliquidoverflowmouthafterstoppinggrouting,groutingandclosedmouth,inordertocarryoutthenextfilling.
(6)openmouth,closedmouthfilling.
Cast-in-situconcreteslab;crack;control;processing:
inbuildingconstruction,concreteslabcastinginsiteoftenvaryinsize,depthofthecrackphenomenon,throughtheanalysisofcracksincast-in-placeconcretefloorperformancestatus,revealsthecausesofcracks,andputsforwardhowtocontrolthefundamentalmeasuresofpreventionandtreatment.
Oneoftheimportantproblemsofcrackscontrolofreinforcedconcreteconstruction,cast-in-placeconcretefloorcrackisoneofthemostdifficultproblemsintheconstructionofrecognized,thesecracksnotonlyaffectstheappearanceofthebuilding,andtheinfluenceofthebuildingusefunction,greatlyreducesthedurabilityofbuildingstructure;destructionofstructuralintegrity,reducethestiffness;
Rebarcorrosion.Sohowtosolvethecommonconcretecracks,designersandconstructionpersonnelcannotbeignored.Acrack,inclinedcrackperformance:
distributionintheflooroftheroomonthecornerofthehousingwallcracks,general45ooblique,sometimesacornertwocracksappearatthesametime,basicallytocrackdownthrough.Asasevenstoreyframeresidentialbuildingproject,thetotallengthofthestructureisabout100m,equippedwithtwotemperaturejoint,thesideofthebasefortherestofstripfoundationandindependentfoundationslab.Inabouttwomonthsafterthehandoversuddenlyfoundononespancolumnplateaturrettemperaturecracks45.Cracks,fromthreelayerstosixfloorseachhave3,butnotthroughthefloor.
Theverticalandhorizontalcracks:
mainlyforthelongitudinalandtransversecracks.Asateachingbuilding,thecast-in-placereinforcedconcreteflooroflargeareawidthof0.10.3mmrangingfromlongitudinalandtransversecracks.
Thesurfacecracks:
suchcracksmainlycracksintheconstructionprocess,easycontrolandtreatment.Asaprojectunderconstruction,becausethesurfaceareaislarge,intheeveningpouredconcrete,themorningoftheseconddayforwatering,butbeforepouringbacktokill,surfacecracksappearedatnoon,withthenakedeyecanidentify.Effectoftworeasons,concretefloorcrack1.concretematerials
TheeffectofcementcementshrinkagevaluedependsontheC3A,likeSO3,gypsumcontentandfinenessofcementetc..ThecontentsofC3A,thefinenessoffinecementshrinkage.Thecontentofgypsuminsufficientcement,hasalargercontraction,whilethecontentofSO3ontheinfluenceofconcreteshrinkagesignificantly.
Theinfluenceofaggregate:
withtheincreaseofthecontentofaggregateconcreteshrinkagedecreaseswiththeincreaseofaggregateelasticmodulusdecreases,atthesametime,andincreasedwiththeincreaseofclaycontentinaggregate.Inaddition,intheconcrete,theaggregategradationisnotveryreasonableisthemainfactorscausingcracksinconcrete.
Theinfluenceofconcretemixratio:
includingunitwater,cementcontent,watercementratio,sandratioandmortarratio.Intheunitwateruseanddosageofcementconcreteshrinkagedepends,andwatereffectsthanthecementcontent;inwaterundercertainconditions,shrinkageincreaseswiththeincreaseofthedosageofcementdryconcrete,butincreasedinthemassratio;undercertainconditions,shrinkageincreaseswiththeincreaseofwatercementratiosignificantlyincreaseddryconcrete;mixinthesameconditions,thedryshrinkagerateincreaseswiththeincreaseofsandconcrete,buttoalesserextent.
Theadditivetypeandcontent:
theinfluenceofmixedwithchemicaladmixturescanmaketheshrinkageofconcreteincreases.Superplasticizerusedtoimproveconcreteworkability,increaseslump,superplasticizerconcreteisgreaterthanthenondopedchargeshortening