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Gradientdomesticationandselectionofmineralizingmicroorganismssuitableforthe
internalenvironmentofhydraulicconcrete
2
1,2
1,2
2
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MENGYongdong ,XUXiaowei,DINGYi,WANGYu,CAIZhenglong ,TIANBin 1,2
(1.HubeiKeyLaboratoryofHydropowerEngineeringConstructionandManagement,
ChinaThreeGorgesUniversity,Yichang 443002,China;
2.CollegeofHydraulicandEnvironmentEngineering,ChinaThreeGorgesUniversity,Yichang 443002,China)
Abstract:Theharshalkalineconditionswithintheinternalstructureofhydraulicconcreteconstraintheself - heal
ingefficacyofmicrobialconcrete.Thisstudyemploysagradientdomesticationmethodtoenhancethealkalinetoler
anceofmineralizedmicroorganisms ,selectingenhancedalkaliphilicmicroorganismsthatarewell - suitedtothepore
environmentofconcreteandpossessaheightenedcapacityforinducingmineralizationdeposition.Initially,under
highalkalineconditionsinlaboratory,theactivityandinducedmineralizationdepositionoffourBacillusspecies(B.
megaterium , B.cohnii, B.subtilis, and B.pasteurii)were compared.Microorganismsexhibiting superior
alkalineresistancewerepreliminarilyselected ,andanadaptivealkalinetolerancedomesticationprocesswascon
ducted.Subsequently,acomprehensiveinvestigationoftheimpactofdomesticatedmicroorganismsonconcreteme
chanicalproperties,capillarywaterabsorption,waterpermeability,andself - healingcapabilitywasundertaken.
ScanningelectronmicroscopyandX - raydiffractiontechniqueswereemployedforthecharacterizationofthemicro
scopicmorphologyandcompositionofmineralizedproducts.Theresultsindicatethat ,incomparisontoB.megate
rium,B.cohnii,andB.subtilis,B.pasteuriidemonstrateshigheractivityunderhighalkalineconditions.The
gradientdomesticationtechniquefurtherenhancestheactivityofB.pasteuriiinhighalkalineenvironments ,confir
mingthattheenhancedalkalineresistancethroughthismethodexhibitsmultigenerationalretentioncharacteristics.
Incomparisontothe28 - dayunmodifiedmicrobialsamples ,thecompressivestrengthofconcreteincorporatingdo
mesticatedmicroorganismsincreasedby16.59%,andwaterabsorptiondecreasedby37.74%.Additionally,the
maximumclosedcrackwidthwas0.57mm ,exceedingthe0.44mmoftheunmodifiedbacterialgroup.Comparedto
unmodifiedbacterialsamples ,thewaterpermeabilitycoefficientofdomesticatedbacterialsamplesdecreasedby
19.22% at28days.Thisresearchprovidesaviablestrategyforimprovingtheefficiencyofmicrobial - inducedcalci
umcarbonateprecipitationinconcrete.
Keywords:hydraulicconcrete;cracksself - repairing;mineralizedmicroorganisms;gradientdomestication;micro
analysis
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