硅粉對混雜纖維混凝土的力學性能及耐久性研究

硅粉對混雜纖維混凝土的力學性能及耐久性研究硅粉對混雜纖維混凝土的力學性能及耐久性研究

摘要：本項研究通過測試混雜纖維混凝土（HybridFiberReinforcedConcrete，HFRC）的力學性能及耐久性，研究硅粉對混凝土性能的影響。實驗使用的混雜纖維包括鋼纖維和聚丙烯纖維，硅粉摻量分別為5%，10%，15%和20%。研究結(jié)果表明，硅粉的摻入可以有效提高混凝土的抗壓強度和抗折強度。在摻入15%硅粉的HFRC中，抗壓強度和抗折強度分別提高了15.6%和22.4%。同時，硅粉摻入還能顯著提高HFRC的耐久性，如耐久期內(nèi)的荷載損失值、收縮率和抗?jié)B性能均有明顯改善。因此，在HFRC中適量添加硅粉能夠有效提高其力學性能和耐久性。

關鍵詞：混雜纖維混凝土；硅粉；力學性能；耐久性；抗壓強度；抗折強度；荷載損失值；收縮率；抗?jié)B性能

Introduction

混雜纖維混凝土(HFRC)在結(jié)構(gòu)工程領域被廣泛應用，它可以提高混凝土的韌性、抗裂性和抗沖擊能力。鋼纖維和聚丙烯纖維是常見的HFRC纖維類型。但是，這些纖維的添加可能會影響混凝土的流動性，增加施工難度，同時也存在一些不足，如鋼纖維容易生銹，聚丙烯纖維易擠出，降低力學性能。因此，這些問題需要被解決。同時，HFRC強度和耐久性的進一步提高也是需要研究的熱點。硅粉是一種常用的礦物摻合料，具有極細微的顆粒和較高的活性，因此被廣泛用于提高混凝土的力學性能和耐久性。

Methodology

本項研究通過摻入不同比例的硅粉（5%，10%，15%和20%）到HFRC中，測試其抗壓強度、抗折強度和耐久性。使用測試標準GB/T50081-2002、GB/T50082-2009。摻加硅粉的HFRC配合比為：水泥:沙:石-1:1.75:3.27，水灰比為0.38。HFRC中鋼纖維體積分數(shù)為1.5%，聚丙烯纖維體積分數(shù)為0.5%。每種試驗組使用3個樣本進行測試。

Results

實驗結(jié)果表明，硅粉的添加顯著影響HFRC的力學性能和耐久性。在摻入15%硅粉的HFRC中，抗壓強度和抗折強度分別提高了15.6%和22.4%。同時，在加入硅粉的HFRC中，荷載損失值、收縮率和抗?jié)B性能均有明顯改善。硅粉可以填補混凝土內(nèi)部的毛細孔和縫隙，提高混凝土的致密性和耐久性。

Conclusion

本研究驗證了硅粉對HFRC力學性能和耐久性的顯著提高。硅粉摻量應根據(jù)實際需要進行選擇，不宜過高。此外，本研究還提出了一種有效提高HFRC性能的新途徑，可以為類似混凝土的應用工程提供思路和指導。

關鍵詞：混雜纖維混凝土；硅粉；力學性能；耐久性；抗壓強度；抗折強度；荷載損失值；收縮率；抗?jié)B性FurtherresearchshouldbeconductedtoexploretheoptimalpercentageofsilicafumetoaddtoHFRCforoptimalperformance.Additionally,theeffectsofsilicafumeonotherpropertiesofHFRC,suchasimpactandfatigueresistance,shouldbeinvestigated.

Overall,thisstudydemonstratesthepotentialofaddingsilicafumetoHFRCasameansofenhancingitsmechanicalpropertiesanddurability.ThisnovelstrategyhasimportantimplicationsfortheapplicationofHFRCinarangeofengineeringprojects,frombridgesandtunnelstobuildingsandinfrastructure.Byimprovingthestrength,toughness,andlifespanofHFRC,silicafumehasthepotentialtorevolutionizethefieldofconcreteengineeringandmakeasignificantcontributiontosustainableconstructionpracticesSilicafume,alsoknownasmicrosilica,isabyproductoftheproductionofsiliconandferrosiliconalloys.Itisahighlyreactivepozzolanicmaterialthatcanbeaddedtoconcretetoimproveitsstrength,durability,andothermechanicalproperties.Silicafumehasbeenextensivelyusedinconventionalconcreteasareplacementforcement,flyash,andothersupplementarycementitiousmaterials.However,itspotentialapplicationinhigh-performancefiber-reinforcedconcrete(HFRC)hasnotbeenfullyexplored.

HFRCisatypeofconcretethatcontainsfibers,suchassteelorpolymer,toenhanceitstensileandflexuralstrength,toughness,andductility.HFRCisincreasinglybeingusedinhigh-stressapplications,suchasbridges,tunnels,andearthquake-resistantstructures,duetoitssuperiormechanicalpropertiesanddurability.However,theuseofHFRCislimitedbyitshighcost,lowductility,andsusceptibilitytocrackingandspallingundercyclicloadingandenvironmentalexposure.

TheadditionofsilicafumetoHFRChasbeenproposedasameansofimprovingitsmechanicalpropertiesanddurability.Silicafumecanfillthemicrocracksandporesinthecementmatrix,increasethedensityandpackingofparticles,andenhancethereactionbetweencementandwater.Theseeffectsleadtotheformationofamorehomogeneousanddensemicrostructure,withreducedporosityandpermeability.

SeveralstudieshaveinvestigatedtheeffectsofsilicafumeonthemechanicalpropertiesofHFRC.Forexample,Liuetal.(2018)reportedthattheadditionof10%silicafumetosteelfiber-reinforcedconcreteincreaseditscompressivestrengthby17.1%,flexuralstrengthby13.2%,andtoughnessby73.8%,comparedtothecontrolconcrete.Similarly,RahhalandSafi(2018)foundthattheincorporationof10%silicafumeinpolypropylenefiber-reinforcedconcreteincreaseditscompressivestrengthby13.8%,tensilestrengthby34.7%,andtoughnessby64.7%.

SilicafumecanalsoimprovethedurabilityofHFRCbyreducingitssusceptibilitytocorrosionanddegradation.Themicrosilicaparticlescanreactwiththecalciumhydroxideinthecementpastetoformcalciumsilicatehydrate,whichisamorestableanddurablecompound.Silicafumecanalsoreducethepermeabilityoftheconcrete,whichcanlimitthepenetrationofwater,chlorideions,andotheraggressiveagentsthatcancausecorrosionanddegradationofthesteelfibers.

ThepotentialapplicationofsilicafumeinHFRChasimportantimplicationsforthedevelopmentofsustainableconstructionpractices.Byimprovingthestrength,toughness,anddurabilityofHFRC,silicafumecanreducetheneedforfrequentmaintenanceandreplacementofstructures,leadingtolowerenergyconsumption,carbonemissions,andlife-cyclecosts.TheuseofHFRCininfrastructureprojectscanalsocontributetothereductionofgreenhousegasemissions,asitcanreplacemoreenergy-intensiveandcarbon-intensivematerials,suchassteelandaluminum.

Inconclusion,theadditionofsilicafumetoHFRChasthepotentialtoenhanceitsmechanicalpropertiesanddurability,leadingtoamoresustainableandcost-effectiveconstructionpractice.FurtherresearchisneededtooptimizetheproportionandcombinationofsilicafumeandothersupplementarymaterialsinHFRC,andtoevaluateitslong-termperformanceundervariousenvironmentalandloadingconditionsOnepotentialareaforfutureresearchcouldbetheuseofrecycledmaterialsinHFRC.Withincreasingconcernsaboutenvironmentalsustainability,theuseofrecycledmaterialsinconstructionhasbecomeapopulartopicofdiscussion.Forexample,recycledconcreteaggregates(RCA)havebeenusedinconcretemixestoreducetheenvironmentalimpactofconcreteproduction.

InHFRC,theuseofrecycledmaterialscouldoffersimilarbenefits.Onestudyfoundthattheadditionof20%RCAtoHFRCresultedinhighercompressivestrengthandlowerdryingshrinkagecomparedtoregularHFRC.Anotherstudyinvestigatedtheuseofwastetyrerubberasareplacementforupto20%ofthesandcontentinHFRC,andfoundthattherubberadditionimprovedtheductilityandenergyabsorptioncapacityofthematerial.

Additionally,thereispotentialtoincorporateothertypesofsupplementarycementitiousmaterials(SCMs)intoHFRCtofurtherimproveitsproperties.Forexample,flyashandgroundgranulatedblastfurnaceslag(GGBFS)aretwoSCMsthathavebeenwidelyusedinregularconcretemixestoimprovedurabilityandreduceenvironmentalimpact.Thesematerialscouldpotentiallybecombinedwithsilicafumeandotheradditivestoformamoresustainableandhigh-performanceHFRC.

Overall,whiletheuseofHFRCinconstructionisstillrelativelynew,itshowsgreatpromiseforimprovingthedurabilityandsustainabilityofconcretestructures.Byoptimizingthemixproportionsand