Reusing Construction and Demolition Waste to Prepare Alkali-Activated Cement 2022 María V. Borrachero.pdf

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materials
Article
ReusingConstructionandDemolitionWastetoPrepare
Alkali-ActivatedCement
Marí,*,JordiPayá1,SantiagoBrito1,YasnaPamelaSegura2,LourdesSoriano1,
íaMonzó1
1InstituteofConcreteScienceandTechnology(ICITECH),UniversitatPolitècnicadeValència,
46022València,Spain;******@(.);******@(.);
******@(.);******@(.);******@(.)
2DepartmentoDengenieriadelaConstruction,UniversidaddeMagallanes,º.,
PuntaArenas6210427,Chile;yasna.******@
*Correspondence:******@
Abstract:Largeamountsofwastearederivednotonlyfromconstructionprocesses,butalsothe
,whichmakes

employedasflllermaterialorrecycledaggregateinconcrete,
presentworkproposesreusingconstructionanddemolitionwastetomanufacturealkali-activated
(C&DW)from
ademolitionwastecollectionplantinValencia(Spain)wasphysicallyandchemicallycharacterised.
Thisresiduecontainedlargefractionsofconcrete,mortar,bricks,-ray
fluorescence(XRF)analysisshowedthatitschemicalcompositionwasmainlyCaO,SiO2andAl2O3.
X-raydiffraction(XRD)analysisrevealedthatitpresentedsomecrystallineproducts,andquartz
(SiO2)andcalcite(CaCO3)&DWandblastfurnaceslag(BFS)
werealkali-
Citation:Borrachero,.;Payá,J.;pasteswerecharacterisedbytechniquessuchasthermogravimetryandscanningelectronmicroscopy
Brito,S.;Segura,.;Soriano,L.;(SEM).Thealkali-activatedmortarswereprepared,andtheresultingmortars’compressivestrength
Tashima,.;Monzó,,whichwasashighas58MPawiththe50%C&DW-50%
ConstructionandDemolitionWasteconcludedthatitispossibletomakenewsustainablebindersbythealkaliactivationofC&DW-BFS
toPrepareAlkali-.
Materials2022,15,://
/ma15103437Keywords:valorisation;constructionanddemolitionwaste;blastfurnaceslag;compressive
AcademicEditor:PaolaPalmerostrength;microstructure
Received:11April2022
Accepted:8May2022
Published:10May2022

Publisher’sNote:MDPIstaysneutralTheEuropeanCommissionWasteFrameworkDirectiveprovidesbasicwastemanagement-
withregardtojurisdictionalclaimsin
,EuropeanUnionMember
publishedmapsandinstitutionalaffll-
,by2020,mustuse70%non-hazardouswastefromconstructionanddemolition
works[1].Constructionanddemolitionwaste(C&DW)isassumedtocompriseatleast
30%ofalltotalsolidwasteworldwide[2].Dependingontheconstructiontype,several
constructionmaterialwastetypescanbefoundinC&DWcompositions:mortar,concrete,
Copyright:©,bricks,ceramicsanitaryware,steel,etc.
LicenseeMDPI,Basel,,Chinaproduced2360milliontonnesofC&
Thisarticleisanopenaccessarticleamountthesameyear:forexample,Germanyalonecontributed225milliontonnes[3].
distributedunderthetermsandChinaisthelargestproducerofC&DW,,
conditionsoftheCreativeCommonsthemainuseofC&DWistoreplacenaturalaggregatestoproducemortarandconcrete.
Attribution(CCBY)license(https://Nevertheless,large-scaleC&DWreusetowardsacirculareconomysystemneedstobe
[4].
/).
Materials2022,15,:///ma15103437:.
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Inlinewiththis,Lopezetal.[5]proposedactionstrategiesbasedonflvemainstages:
preconstruction;constructionandrenovation;collectionanddistribution;endoflife;ma-
,fourpotentialoutputs
forC&DWusewerepointedout:substitutionof100%rawmaterialforC&DW;recov-
eredmaterialswithpartiallyrecycledcontenttosubstitutematerialsofasimilarnature;
recoveredmaterialtosubstitutecomponentsofmaterialsofadifferentnature;lowered
energydemand.
EmployingC&DWasaprecursorinalkali-activatedcementsisanewwaytovalorise
-scaleC&DWuseisprobablyrelatedto
itshighheterogeneityand,consequently,,moststudies
havefocusedonutilisingspeciflcC&DWparts/.[6]studiedusing
amixtureofgroundwasteconcrete(GWC)andtheflyash(FA)typesasprecursorsin
geopolymericpasteswithdifferentconcentrationsandproportionsofNaOHandsodium
silicate(SS).GWCwaspreparedwithconcretemadeinthelaboratorytoanalyseunconflned
compressivestrength(UCS),SEM/EDS,
withthe50%GWC-50%FAmixtureforalltheNaOHconcentrations(5Mand10M)andat
twoSS/NaOHratios(1and2).Accordingtotheauthors,thepresenceofcalciuminGWC
enhancedstrengthduetotheco-existenceofCSHgelandtheincorporationofCa+2into
thegeopolymerstructure.
Severalstudieshavedemonstratedthepotentialofceramicwasteasaprecursor
inalkali-
materials,suchasblastfurnaceslag(BFS)orfluidcatalyticcrackingresidue(FCC)[7–9].
AninterestingresearchworkwasbyKioupisetal.[10],whoproposedusingrejected
bricksasaprecursorandglasswastetofabricatewindowpanesasacomponentofthe
alkaline-
authorsprepareddifferentmixturestoobtainspecimenswithamaximumcompressive
strengthof32MPaafter7daysofcuring.
Vasquezetal.[11]utilisedC&DW(concretestructuredebris)topreparesingle,hybrid
andbinarypasteswithC&DW,cement(OPC)andmetakaolin(MK),
binarypastes,theauthorsconsideredtheproportionbetweenMKandC&DWtocalculate
theSiO2/,themolarratiointhehybridpastes
wascalculatedonlywiththequantityofC&(onlyC&DW),SS
additionenhancedthecompressivestrengthofthesampleactivatedwithonlyNaOH,by
288%.Thepresenceof10%
at28curingdaysinanambienttemperatureversus25MPaobtainedfromthepastewith
100%C&,thecompressivestrengthofthehybridmixturewith30%OPCwas
33MPa,achievedunderthesamecuringandactivatorconditionsastheaforementioned

severalcrystallinephasesofC&DWandcontributedtobettermechanicalproperties.
Robayo–&DWintofractionstoprepareblocks
fabricatedwith100%,mortarwaste,masonrywaste
andceramicwaste[12].Thecoarseaggregatewasformedbyconcretewaste,andthe
flneaggregatewasformedbymortarwasteandceramicwaste(redandwhite).Finally,
theprecursorofthegeopolymericmixturewas10%OPCand90%C&DW(25%concrete
waste,25%mortarwaste,25%masonrywasteand25%ceramicwaste).Theflrstpartofthe
studyinvolvedperformingthebinderoptimisationofthehybridmixture(OPC-C&DW)at
differentNaOH+SS/precursorandNaOH/,
’scompressive
strengthwith100%’sspecimenswas
,thesolidconcreteblock
preparationdemonstratedthissystem’
thespeciflcationsofahigh-classstructuralblock.
Thesameauthorsrecentlypublishedacommunicationwithaneco-houseproto-
type[13].Theycomparedthebehaviourofthealkali-activatedblocksobtainedfromdiffer-:.
Materials2022,15,xFORPEERREVIEW3of15
precursors:naturalvolcanicpozzolanwithgroundgranulatedBFS,FA,C&DWandredclay
-strengthstructuralblockwasthe
Materials2022,15,34373of15
mixturewithC&DWbecausetheblockdidnotmeetthewaterabsorptioncriterion.
TwomarinesedimentsanddifferentC&DWfractionswerestudiedasprecursorsto
preparepastesactivatedwithKOHandSS[entprecursors:naturalvolcanicpozzolanwithgroundgranulatedBFS,FA,C&DWandred14].Sedimentssubstitutedfractionsof10%
and30%tiles,-strengthstructuralblocktepasteprovedtobetheworstsamplebe-
causethisfractionhadasmallquantityofSiOwasthemixturewithC&.
enhancedthecompressivestrengthofalltheC&&DWfractionswerestudiedasprecursorsto
reachedinanotherpaperpublishedbythepreparepastesactivatedwithKOHandSS[14sameauthor,whichdemonstratedthatcon-].Sedimentssubstitutedfractionsof10%
and30%tiles,
cretewastealwaysyieldedcompressivestrengthsbelow15MPaversusthetileandbrick

waste,which,respectively,obtaenhancedthecompressivestrengthofalltheC&[15].
reachedinanotherpaperpublishedbythesameauthor,whichdemonstratedthatconcreteThepresentstudyaimstoassessthepotentialofusingrealC&DWfromawaste-
sortingandrecoveryplantinValencia(eastSpain).Systematicwastecharacterisationwaswastealwaysyieldedcompressivestrengthsbelow15MPaversusthetileandbrickwaste,
performed,,respectively,[15].
compressivestrengthandmicrostructuralpropertiesofthealkali-activatedcementsbasedThepresentstudyaimstoassessthepotentialofusingrealC&DWfromawaste-
sortingandrecoveryplantinValencia(eastSpain).Systematicwastecharacterisationwas
onC&DW/BFSactivatedattwodifferentSiO2/Na2Omolarratioswereassessedfortwo
performed,
-activatedcementsbasedrtoftheprecursorisduetothefactthat
itisawell-knownmaterialintheliteratureofalkalineactivationandthatithasamplyonC&DW/BFSactivatedattwodifferentSiO2/Na2Omolarratioswereassessedfortwo
[16].
itisawell-knownmaterialintheliteratureofalkalineactivationandthatithasamplyThemainobjectiveoftheinvestigationistovaloriseC&DWresidueintheconstruc-
[16].
ThemainobjectiveoftheinvestigationistovaloriseC&DWresidueintheconstruction
,contributingtothedevelopmentofthe
circulareconomyindustrycouldbeusedagainasarawmaterial,contributingtothedevelopmentofthe
circulareconomy


&&DWConditioningandCharacterisation
Figure1showsadiagramofthedifferenFigure1showsadiagramofthedifferentareasintheSECOPSAMedioAmbientetareasintheSECOPSAMedioAmbiente
,Valencia(Spain).,Valencia(Spain).
.
Figure2ashowstheas-receivedC&-
tainedinstep4beforemanualclassification.
:.
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Materials2022,15,xFORPEERREVIEW4of15
Figure2ashowstheas-receivedC&
instep4beforemanualclassiflcation.
Fig