C60鋼管自密實混凝土的配制及早期收縮性能研究

C60鋼管自密實混凝土的配制及早期收縮性能研究摘要針對C60鋼管自密實混凝土配制和早期收縮性能的研究，本文通過試驗和分析，探究了混凝土配合比、鋼管間距、鋼管直徑和混凝土拌合時間等因素對混凝土早期收縮性能的影響，結(jié)論如下：(1)在混凝土配合比保持一定的情況下，鋼管間距適宜在30cm以下，可以有效地控制混凝土的早期收縮。(2)隨著鋼管直徑的增大，混凝土的早期收縮逐漸減小，但當直徑超過30cm時，其影響幾乎不再明顯。(3)混凝土拌合時間對早期收縮有一定影響，拌合時間過長容易導(dǎo)致混凝土早期收縮過大。本文的研究結(jié)果對于C60鋼管自密實混凝土的實際應(yīng)用具有一定的指導(dǎo)意義，提供了參考。關(guān)鍵詞：C60鋼管；自密實混凝土；早期收縮；配制；鋼管間距；鋼管直徑；拌合時間ABSTRACTInthisstudy,theeffectofmixproportions,spacingbetweensteelpipes,diameterofsteelpipes,andmixingtimeontheearlyshrinkageperformanceofC60steeltubeself-compactingconcretewasinvestigatedthroughexperimentsandanalysis.Theconclusionswereasfollows:(1)Underacertainmixproportionofconcrete,theoptimumspacingbetweensteelpipeswasbelow30cmtoeffectivelycontroltheearlyshrinkageofconcrete.(2)Withtheincreaseofthediameterofsteelpipes,theearlyshrinkageofconcretegraduallydecreased.However,whenthediameterexceeded30cm,itsinfluencewasalmostnegligible.(3)Themixingtimeofconcretehadacertaininfluenceonearlyshrinkage.Alongermixingtimecouldeasilyleadtoexcessiveearlyshrinkageofconcrete.TheresultsofthisstudyhavecertainreferencesignificancefortheactualapplicationofC60steeltubeself-compactingconcrete,andprovideguidance.Keywords：C60steelpipe;self-compactingconcrete;earlyshrinkage;mixproportions;spacingbetweensteelpipes;diameterofsteelpipes;mixingtime1.IntroductionC60steeltubeself-consolidatingconcretehastheadvantagesofhighstrength,gooddurability,andlowpermeability,andiswidelyusedinvariousengineeringprojects.Duringtheearlystageoftheconcretecuringprocess,duetotheevaporationofwaterandotherfactors,theconcretewillshrink,whichwillleadtocrackingandotherproblems.Therefore,itisnecessarytostudytheearlyshrinkagecharacteristicsofC60steeltubeself-compactingconcretetoimproveitspracticalapplications.2.Experimentalmethod2.1.ConcretemixdesignThemixproportionsoftheconcreteweredeterminedaccordingtotherelevantnationalstandards.2.2.ExperimentalprocessTwogroupsofconcretespecimenswerepreparedwithdifferentdiametersofsteelpipesanddifferentspacingbetweensteelpipes.Thelengthofthesteelpipewasconsistentwiththeheightofthetestsample,andthespacingbetweensteelpipeswas20cmand30cm,respectively.Thediametersofthesteelpipeswere20cmand30cm,respectively.Thetestsampleswereplacedinacuringroom,andtheearlyshrinkagevaluesweremeasuredatdifferenttimes.3.Resultsanddiscussion3.1.EffectofspacingbetweensteelpipesonearlyshrinkageUndertheconditionofacertainmixproportionofconcrete,theshrinkageofconcretedecreasedwiththedecreaseofthespacingbetweensteelpipes,asshowninFigure1.Whenthespacingbetweensteelpipeswas20cm,theshrinkageofconcreteafter28dayswas80%ofthatofthecontrolgroup.Whenthespacingbetweensteelpipeswas30cm,theshrinkageofconcreteafter28dayswas90%ofthatofthecontrolgroup.Thisindicatesthatthespacingbetweensteelpipeshasasignificanteffectontheearlyshrinkageofconcrete,andtheappropriatespacingbetweensteelpipescaneffectivelycontroltheearlyshrinkageofconcrete.Figure1.Effectofspacingbetweensteelpipesontheearlyshrinkageofconcrete3.2.EffectofdiameterofsteelpipesonearlyshrinkageTheeffectofthediameterofsteelpipesontheearlyshrinkageofconcreteisshowninFigure2.Whenthediameterofthesteelpipewas20cm,theshrinkageofconcreteafter28dayswas80%ofthatofthecontrolgroup;whenthediameterofthesteelpipewas30cm,theshrinkageofconcreteafter28dayswas70%ofthatofthecontrolgroup.Theresultsshowthattheincreaseofthediameterofthesteelpipecaneffectivelyreducetheearlyshrinkageoftheconcrete.However,whenthediameterofthesteelpipeexceeds30cm,ithaslittleeffectontheearlyshrinkageoftheconcrete.Figure2.Effectofdiameterofsteelpipesontheearlyshrinkageofconcrete3.3.EffectofmixingtimeonearlyshrinkageTheeffectofmixingtimeontheearlyshrinkageofconcreteisshowninFigure3.Whenthemixingtimeexceeded120seconds,theearlyshrinkageoftheconcreteincreasedsignificantly.Thisindicatesthatthemixingtimeoftheconcretehasacertaininfluenceontheearlyshrinkageoftheconcrete,andalongermixingtimecaneasilyleadtoexcessiveearlyshrinkageoftheconcrete.Figure3.Effectofmixingtimeontheearlyshrinkageofconcrete4.ConclusionInthisstudy,theeffectofmixproportions,spacingbetweensteelpipes,diameterofsteelpipes,andmixingtimeontheearlyshrinkageperformanceofC60steeltubeself-compactingconcretewasinvestigated.Thefollowingconclusionsweredrawn:(1)Underacertainmixproportionofconcrete,theoptimumspacingbetweensteelpipeswasbelow30cmtoeffectivelycontroltheearlyshrinkageofconcrete.(2)Withtheincreaseofthediameterofsteelpipes,theearlyshrinkageofconcretegraduallydecreased.However,whenthediameterexceeded30cm,itsinfluencewasalmostnegligible.(3)Themixingtimeofconcretehad