C60钢管自密实混凝土的配制及早期收缩性能研究

C60钢管自密实混凝土的配制及早期收缩性能研究摘要针对C60钢管自密实混凝土配制和早期收缩性能的研究，本文通过试验和分析，探究了混凝土配合比、钢管间距、钢管直径和混凝土拌合时间等因素对混凝土早期收缩性能的影响，结论如下：(1)在混凝土配合比保持一定的情况下，钢管间距适宜在30cm以下，可以有效地控制混凝土的早期收缩。(2)随着钢管直径的增大，混凝土的早期收缩逐渐减小，但当直径超过30cm时，其影响几乎不再明显。(3)混凝土拌合时间对早期收缩有一定影响，拌合时间过长容易导致混凝土早期收缩过大。本文的研究结果对于C60钢管自密实混凝土的实际应用具有一定的指导意义，提供了参考。关键词：C60钢管；自密实混凝土；早期收缩；配制；钢管间距；钢管直径；拌合时间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