A state-of-the-art review on delayed ettringite attack on concrete

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1、Cement&ConcreteComposites25(2003)401–407www.elsevier.com/locate/cemconcompAstate-of-the-artreviewondelayedettringiteattackonconcreteM.Collepardi*CivilEngineeringFaculty,LeonardoDaVinci,Politechnic,Milan,ItalyAbstractThepaperpresentsacriticalreviewofthesulp

2、hateattackrelatedtoettringiteformation.Thisprocessisassociatedwithex-pansion.However,notnecessarilyanyettringite-relatedexpansionisrelatedtothesulphateattack.Forexample,earlyettringiteformationwhichoccursimmediately(withinhours)inaplasticfreshmixturedoesno

3、tproduceanydamagingexpansionandisassociatedwiththeregulationofsettingtimeofPortlandcementpaste.Expansionafterthehardeningofcementpastecanbeadvantageouslyusedforthedevelopmentofchemicalprestressinexpansivecements.Delayedettringiteformation(DEF)occursatlatea

4、gesandtherelatedheterogeneousexpansioninahardenedconcretecanproducecrackingandspalling.TwodifferenttypesofDEFareexamineddependingonthesulphatesource:DEFcausedbyexternalsulphateattackorinternalsulphateattack.Ó2003PublishedbyElsevierScienceLtd.Keywords:Delaye

5、dettringiteformation;Expansion;Sulphateattack1.Introduction2.EttringiteformationEttringiteformationisconsideredtobethecauseofEttringiteformationisassociatedwithexpansionandmostoftheexpansionanddisruptionofconcretemanyhypothesesofettringiterelatedexpansionh

6、avestructuresinvolvedinthesulphateattack[1].However,beenadvanced[2–4].However,notnecessarilyanyet-notnecessarilyanysulphateattackiscausedbyet-tringite-relatedexpansionproducesdamagingdisrup-tringiteformation[2].Moreover,ettringiteformationtionofconcretestr

7、uctures.canbeadvantageouslyusedwithoutanysulphateattackWhenettringiteoccurshomogeneouslyandimmedi-forthedevelopmentofshrinkage-compensatingcon-ately(withinhours),itdoesnotcauseanysignificantcretebyusingexpansivecements.localizeddisruptiveaction(earlyettring

8、iteformation,ThepurposeofthisreviewistopresentcriticalEEF).Thistypeofharmlessettringiteformationhap-analysisoftherelationshipbetweenettringiteformationpens,forinstance,whengypsumreactswithanhydrousandsulphate