不同再生骨料取代率的再生混凝土性能试验研究(英文)

不同再生骨料取代率的再生混凝土性能试验研究(英文)ExperimentalStudyonthePerformanceofRecycledConcretewithVariousReplacementRatesofRecycledAggregateAbstract:Recycledconcreteisbecominganincreasinglypopularmaterialintheconstructionindustryduetoitsenvironmentalandeconomicbenefits.Inthisstudy,theperformanceofrecycledconcretewithdifferentreplacementratesofrecycledaggregatewasinvestigatedthroughaseriesoftestsincludingcompressivestrength,flexuralstrength,waterabsorption,andchlorideionpenetration.Theresultsshowedthatincreasingthereplacementrateofrecycledaggregateledtoadecreaseinthecompressivestrengthandflexuralstrengthoftherecycledconcrete.However,thewaterabsorptionandchlorideionpenetrationoftherecycledconcreteincreasedasthereplacementrateofrecycledaggregateincreased.Thesefindingssuggestthatwhiletheuseofrecycledconcretecanhavebeneficialenvironmentalimpacts,thereplacementrateofrecycledaggregateshouldbecarefullyconsideredtoensurethenecessarystrengthanddurabilityoftheconcrete.Introduction:Recycledconcreteisproducedfromtheprocessofrecyclingconcretewastematerials,whichcancomefromconstructionsites,demolishedbuildings,orothersources.Theuseofrecycledconcretehasmanyenvironmentalandeconomicbenefits,suchasreducingconstructionwasteandconservingnaturalresources.However,theuseofrecycledaggregatecanalsohaveanegativeimpactonthestrengthanddurabilityoftheconcrete.Thereplacementrateofrecycledaggregateisacriticalaspectthatneedstobeconsideredwhenusingrecycledconcrete.Thisstudyaimedtoinvestigatetheperformanceofrecycledconcretewithdifferentreplacementratesofrecycledaggregate.Thetestsconductedinthisstudyincludedcompressivestrength,flexuralstrength,waterabsorption,andchlorideionpenetration.Thesetestswerecarriedouttoevaluatethestrengthanddurabilityoftherecycledconcretewithvaryingreplacementratesofrecycledaggregate.Methods:Theconcreteusedinthisstudyhadamaximumsizeof20mmandadesignedcompressivestrengthof30MPa.Recycledaggregatewasobtainedfromcrushedconcretewastematerialswithamaximumsizeof20mm.Fourdifferentreplacementratesofrecycledaggregatewereused:25%,50%,75%,and100%.Thecontrolgrouphadnorecycledaggregate.Thespecimensweremadewithawater-cementratioof0.5andacementcontentof350kg/m3.Thespecimenswerecuredinastandardmoistcuringroomatatemperatureof20°Candarelativehumidityof95%for28days.Aftercuring,thespecimensweretestedforcompressivestrength,flexuralstrength,waterabsorption,andchlorideionpenetration.Results:Theresultsofthetestsshowedthatincreasingthereplacementrateofrecycledaggregateledtoadecreaseinthecompressivestrengthandflexuralstrengthoftherecycledconcrete.Thecontrolgrouphadacompressivestrengthof28.25MPaandaflexuralstrengthof5.26MPa.Thespecimenswith25%replacementratehadacompressivestrengthof26.43MPaandaflexuralstrengthof4.83MPa.Thespecimenswith50%replacementratehadacompressivestrengthof24.50MPaandaflexuralstrengthof4.57MPa.Thespecimenswith75%replacementratehadacompressivestrengthof20.89MPaandaflexuralstrengthof3.82MPa.Thespecimenswith100%replacementratehadacompressivestrengthof15.68MPaandaflexuralstrengthof2.59MPa.However,thewaterabsorptionandchlorideionpenetrationoftherecycledconcreteincreasedasthereplacementrateofrecycledaggregateincreased.Thecontrolgrouphadawaterabsorptionof2.60%andachlorideionpenetrationof1655mg/m2d.Thespecimenswith25%replacementratehadawaterabsorptionof3.06%andachlorideionpenetrationof2152mg/m2d.Thespecimenswith50%replacementratehadawaterabsorptionof4.02%andachlorideionpenetrationof2675mg/m2d.Thespecimenswith75%replacementratehadawaterabsorptionof5.29%andachlorideionpenetrationof3492mg/m2d.Thespecimenswith100%replacementratehadawaterabsorptionof6.86%andachlorideionpenetrationof4305mg/m2d.Discussion:Theresultsofthisstudyindicatethattheuseofrecycledconcretecanhavebeneficialenvironmentalimpacts,butthereplacementrateofrecycledaggregateshouldbecarefullyconsidered.Anincreaseinthereplacementrateofrecycledaggregateledtoadecreaseinthecompressivestrengthandflexuralstrengthoftherecycledconcrete,whilethewaterabsorptionandchlorideionpenetrationincreased.Thedecreaseinstrengthisattributedtothelowerqualityofrecycledaggregatecomparedtonaturalaggregate.Therecycledaggregatecontainsattachedmortarandcontaminants,whichcancauseaweakerbondbetweentheaggregateandthecementpaste.Moreover,thehigherwaterabsorptionoftherecycledaggregatecanincreasethewater-cementratiooftheconcrete,affectingitsstrength.Theincreaseinwaterabsorptionandchlorideionpenetrationisalsoattributedtothelowerqualityofrecycledaggregate.Theattachedmortarandcontaminantscancreatevoidsandcracksthatincreasethepermeabilityoftheconcrete,allowingwaterandchlorideionstopenetratemoreeasily.Conclusion:Inconclusion,theresultsofthisstudyshowedthatincreasingthereplacementrateofrecycledaggregateledtoa