Elaboration and study of the functional properties of geopolymer foams

Asmaa KADDAMIasmaa.kaddami@ifsttar.fr

Olivier PITOIS, Paméla FAURE

http://navier.enpc.fr/Laboratoire Navier,2 allée Kepler, 77420Champs-sur-Marne, France

Geopolymerfoams:

Foamconcreteisatypeofalightweightconcretethatconsistsofacementitiousbinderwithahighdegreeofvoidspace.

Airincorporationenablestolighten thematterandtoconferthermalandacousticinsulationproperties.

Geopolymerfoamscanbeusedasacousticandthermalinsulators,filters orlightweightfireproofinsulators.

Controllingthenature,size anddistribution ofvoidsisthemostcriticalstepintheproductionofthesefoamssincethevoidsdeterminethedensityandstrength ofthefoamconcrete.

Conciliate mechanical resistance of geopolymer foams and their acoustic and thermal insulation

properties

à Morphology optimization

Objective:

ExampleofanaeratedPortlandcementmortar

0,1

1

10

0 100 200 300 400 500 600 700

Mecha

nicalresistan

ce(M

Pa)

density(kg/m^3)

Hung2013

Sanjayan2015

Skvara2014

Samson2016(40°C)

Samson2016(20°C)

Liu2016

Liu2015

Dembovska2017

Palmero2015

Zhang2014

Verdolotti2015

Kargin2017

Hajimohammadi2017

Bai2017

Bai2016

?

Intheliterature:>ThedensitiesofGeopoymer foamsmadetillnowareover200Kg/m3

Formulation(Paste&foam)

MixingFreshstate:

aging

Solidstate:Studyoffunctional

properties

Majorissueencounteredduringtheoptimizationprocess:themorphologyevolvesstronglybeforesetting

Issue:

Formulation(Paste&foam)

MixingFreshstate:

aging

Solidstate:Studyoffunctional

properties

Majorissueencounteredduringthemanufacture:themorphologyevolvesstronglybeforesetting

Destab

ilizatio

nmecha

nism

s

Drainage CoarseningHa

rden

ing

Issue:

Formulation(Paste&foam)

MixingFreshstate:

aging

Solidstate:Studyoffunctional

properties

Majorproblem incountred during theoptimization process:themorphology evolves strongly before thesetting

Controlthekineticsofsetting

Issue:

Kineticsofsettingandrheology:

A.Fernandez-Jimenezetal./MicroporousandMesoporousMaterials(2006)

Duxson etal.(2006)

→Understandingofthetimeevolutionofrheologyofgeopolymerpastesisamajorissuefortheelaborationprocess

Kineticsofsettingandrheology:

A.Favier etal./SoftMatter (2013)

GeopolymerPortlandCement

Rheologicalbehavioroffreshgeopolymer pastes:• Geopolymer pastescanbeassimilatedtosemi-dilutesuspensionsof

non-colloidalparticlesinaNewtonianfluidofhighviscosity.(Roussel &al,2014)

• Freshgeopolymer pasteshaveaverylowyieldstress.

• Oscillatoryrheology(f=1Hz)

!(#) = !0'()# !(#) = !0'(()#++)

!∗ = $% = !′ + (!′′

G’:elasticmodulusG’’:viscousmodulus

• Ultrasonicrheology(f=100KHz)

! ′ = ! =$12

'(1 + *)2[1 − *]²

R:ReflectioncoefficientZ1:acousticimpedanceofthe

medium1

(Rouyer,2013)

Materials&Methods:• Metakaolin (Argical M1200s)+SodiumSilicatesolution

- MonitoringofrelaxationtimesT1 andT2whichcharacterizerespectivelythetimesofreturntotheequilibriumofthelongitudinalandtransversalcomponentsofmagneticmoments,

- T1,2 ~V/S,alreadyusedtocharacterizethesettingofPortlandcement.(P.Faureetal./MagneticResonanceImaging(2008))

à ApplicationofProtonNMRtogeopolymerpastes.

Bruker Minispec MQ20

Methods:• ProtonNMR(H1NMR):

Phase1:formationofanAl-richgelaroundMetakaolin grains(gel1)

Phase2:inductionphase

Phase3:formationofagelofahigherconnectivity(gel2)àsetting

Monitoringoftheelasticmodulususingstandardrheology

Phase1:formationofanAl-richgelaroundMetakaolin grains(gel1)

Phase2:inductionphase

Phase3:formationofagelofahigherconnectivity(gel2)àsetting

Monitoringoftheelasticmodulususingstandardrheology

Monitoringoftheelasticmoduluswith:

Ultrasonicrheology(f=100KHz) Calorimetry

ProtonNMR

- ThecurveT1/T2 illustratesthetransitionfromtheliquidphasetothesolidphase.

- ProtonNMRdefinesacharacteristictimeofgeopolymersetting:(d(T1/T2 )/dt)max

LiquidT1/T2̴1,5

SolidT1/T2̴4

Monitoringoftheelasticmoduluswith:

àProtonNMRisaanindicatorofthesettingtime.

Ultrasonicrheology(f=100KHz) Calorimetry

10

100

1000

10000

100000

0,00

0,50

1,00

1,50

2,00

2,50

3,00

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Elasticm

odulusG

'(Pa)

d(T1/T2)/dt

Time(h)

d(T1/T2)/dt

G',oscillatoryrheology

ProtonNMR

• Allowstomonitorthesettingforlongperiodsoftime

ProtonNMR

?

• Allowstomonitorthesettingforlongperiodsoftime

ProtonNMR

Strategyforbubblesstabilization

1

10

100

1000

10000

100000

1000000

0 1 2 3 4 5

G'(Pa)

Temps(h)Time(h)

Bubblesincorporation

Foamstabilization?

Setting

Mixing5min Rest

Blending5min Foamstabilization

TsTr

Influenceofairincorporationonsettingtime

SequenceforthemeasurementoftheeffectofmixingonthetimeofsettingSecondmixingsimulatesfoamincorporation

- Gel1reformssystematicallyaftereachblendinginthesameway.- Timeofinductionisasmuchreducedasthetimeofrestbeforemixingis

important

Influenceofairincorporationonsettingtime

Blending5min

Measurementofelasticmodulus

Time(h)

Influenceoftemperatureonthetimeofsetting

Thedifferencebetweenthetimest(10000Pa)at20°Cand25°Cis2h43min

10

100

1000

10000

100000

1000000

0 1 2 3 4 5 6 7 8

G'(Pa)

Temps(h)

G'(Pa),20°

G'(Pa),25°

G'(Pa),30°

G'(Pa),40°

Time(h)

EffectofatemperaturesteponthetimeofsettingUnleashthesettingwithatemperaturestepfrom25°Cto40°Cà Gainintimeoffoamstabilization

Time(h)

Elastic

mod

ulusG’(Pa)

Tempe

rature(°C)

Preliminaryworkforgeopolymerfoaming:

Tween80(Sigma-Aldrich)(M.Strozi Cillaetal./CeramicsInternational40(2014))

Preliminaryworkforgeopolymerfoaming:

Tween80(Sigma-Aldrich)(M.Strozi Cillaetal./CeramicsInternational40(2014))

Thankyou!