Reactivity of Calcined Clay in Alite -calcium ...Reactivity of Calcined Clay in Alite -calcium...

ReactivityofCalcinedClayinAlite-calciumSulfoaluminateCementHydration

NatechanokChitvoranundBarbaraLothenbach

SakprayutSinthupinyoFrankWinnefeld

23rd June2015TheSwissTechConventionCenterLausanne

1

Outline

• Introduction

• Materials&Methods

• ResultsI. PozzolanicreactionofcalcinedclayII. PhaseassemblageIII. ThermodynamicmodelingIV. Strengthdevelopment

• Conclusion

2

CO2 emission

50%

5%5%

40%

Ref:- J.S. Damtoft, et al., Sustainable development and climate change initiatives. 2008- http://www.epa.gov/climatechange/ghgemissions/sources/industry.html- http://www.theguardian.com/environment/2011/apr/28/industries-sectors-carbon-emissions

CO2

3

Agriculture

Industry

Transportation

Electricity

CommercialandResidental

Fuelofproduction

Decarbonation ofLimestone

LowCO2 Binders

4

Lowenergyclinker Clinkercontentreduction

Newbindermaterials

• Lowerclinkerizationtemperature• Lowerlimestonecontentinrawmeal

• Usingsupplementarycementitious materials(SCMs)

• Cementfreematerials

• Earlystrengthimprovement• Easytogrind• Resistancetocarbonation

Alite-calciumsulfoaluminate cement

(ACSA)Calcinedclay

• AvailableinThailand• Cheap• Reactive

Ref:I. Odler, Special inorganic cements, 2000

• Introduction



• Conclusion

Outline

5

Materials

6

ACSAclinkersynthesis

≤1300°C

Staticfurnace ACSAclinkerRawmaterials

Limestone

Tuff

Gypsum

C3S C2S C3A C4AF C4A3$ Freelime

55 10 0 12 10 <3

Phasecomposition

CaF2

Alite Ye’elimite

Limestone

Materials

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Calcinedclaycalcination

Kaolinite Amorphous

Beforecalcination 40 40

Aftercalcination 0 81

Kaolinitic clayfromcentralpartofThailand

750°C

Staticfurnace Calcinedclay

Nodehydroxylationpeak

30min

Other phases :microcline, albite, hematite, magnesoichloritoid

Materials

95

85.5

5

4.5

10

75%

80%

85%

90%

95%

100%

ACSA ACSA+Clay

Calcinedclay

Anhydrite

ACSAclinker

10%ofcementreplacementbycalcinedclay

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FixW/Bratio=0.485

Methods

1. Pozzolanicreactivitytestofcalcinedclay§ 0.1MKOH§ 0.3MKOH

2. Hydration§ XRD§ TGA§ Portlanditequantification

3. Thermodynamicmodeling§ Compositionvariationsat100%hydration:Influenceof“calcinedclay”

additiontoACSA

4. Mortarcompressivestrength

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Outline

10

• Introduction



• Conclusion

Pozzolanic reactivity

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Relativeportlanditecontent

12

• Decreasing of portlandite content up to 7 days• Higher portlandite consumption in high concentration condition

Reactiondegreecalculation

13

RemainingCHcontentfromTGAdata

Thermodynamicmodeling

45%ofCH

70%ofreactiondegree

Reactiondegree

14

90%

70%

• 0.1M KOH (pH 12.8) = 70%• 0.3M KOH (pH 13.4) = 90%

At7days ACSA

Phaseassemblage

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Hydrationproducts

ACSA

ACSA+Clay

EMs F 91days

CHE

E

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Additionofclay• MoreMs butlessettringite• Lessportlandite

ACSACrystallinehydrationproducts:ettringite,monosulfate,portlandite

Portlanditequantification

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Portlanditeconsumptionevidenceforcalcinedclaysystem

Thermodynamicmodeling

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Influenceofcalcinedclay

Inert ACSA

InertclayEttringite

Ms

Hc

C−S−H

Stratlingite

Portlandite

Poresolution

• Decreasingettringiteandportlandite• IncreasingMs andC−S−H

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100%ofhydration

Strengthdevelopment

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Compressivestrength

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Higherhydratedphasevolumecontributingtostrength(excludingportlandite)

• Lowerstrengthupto7days

• Higherstrengthat28days

ACSA ACSA+Clay

Outline

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• Introduction



• Conclusion

Conclusion

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• Highreactivity• IncreasingthereactivitywithhigherpH.

Calcinedclay

ACSA+Clay • MoremonosulfateandC-S-Hbutlowerportlanditeandettringite

• Highpozzolanicreactivity• Highcompressivestrengthafter28days• About15%reductionofCO2 emission

THANKYOU

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Reactivity of Calcined Clay in Alite -calcium ...Reactivity of Calcined Clay in Alite -calcium...

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