Utilization of Cement Kiln Dusts for Clay Soil Stabilizationwebpages.mcgill.ca/staff/Group3/aboyd1/web/Conferences... · 2013. 1. 9. · Utilization of Cement Kiln Dusts for Clay

Utilization of Cement Kiln Dusts for Utilization of Cement Kiln Dusts for Clay Soil StabilizationClay Soil Stabilization

Sulapha Peethamparan Clarkson UniversitySulapha Peethamparan Clarkson UniversitySulapha Peethamparan, Clarkson UniversitySulapha Peethamparan, Clarkson UniversityJan Olek, Purdue UniversityJan Olek, Purdue University

Anna Maria Workshop IXAnna Maria Workshop IX-- Nov 11Nov 11--14, 2008 14, 2008 Sustainable Cement; Challenges, Opportunities and ApplicationsSustainable Cement; Challenges, Opportunities and Applications

What are cement kiln dusts (CKDs)? What are cement kiln dusts (CKDs)?

Exhaustt gases

Initial formation Of C2SFormation of initial compounds

formation Of C3S

Raw feed in

Filter• calcined & unreacted raw feed

clinker particles• clinker particles

• alkalis

• sulfates

•other volatiles

Cement Kiln DustApproximately 9 million tones of CKD for

How much CKD is generated ?

Approximately 9 million tones of CKD for every 100 million tones of cement. 5 million tones of CKD are recycled as a raw material and the rest are considered as

11/12/2008 Sulapha Peethamparan, Clarkson UniversityJan Olek, Purdue University

2

waste. Sulapha Peethamparan, Clarkson University

Jan Olek, Purdue University

CKDs and Waste CKDs and Waste MManagementanagement

Pictures courtesy of M. Santagata, Purdue University

• Airborne, air pollution• Leaching of heavy metals

Requires large space for disposal

3Sulapha Peethamparan, Clarkson UniversityJan Olek, Purdue University

• Requires large space for disposal

11/12/2008

Sustainable Alternate SolutionSustainable Alternate Solution

Beneficial utilization of CKDsBeneficial utilization of CKDs--sustainability ofsustainability ofBeneficial utilization of CKDsBeneficial utilization of CKDs--sustainability of sustainability of cement production can be improved by utilizing cement production can be improved by utilizing some of the CKDs in other applications.some of the CKDs in other applications.pppp

ObjectiveTo explore the potential of utilizing CKD as a soilTo explore the potential of utilizing CKD as a soil stabilizing material

Sulapha Peethamparan, Clarkson UniversityJan Olek, Purdue University 411/12/2008

CKD as a soil stabilizer?CKD as a soil stabilizer?

Why Soil Stabilization?

Clay particles before Clay particles after stabilization

Can we substitute the traditional stabilizers with CKDs and would it be beneficial?

C ll CKD ff ti il t bili ? C th t bili b th

y pstabilization

Can we use all CKDs as effective soil stabilizers? Can they stabilize both expansive and non expansive soils?How effective are they compared to lime in stabilizing soils?What is the mechanism of stabilization? How durable are the CKD-t bili d il ?stabilized soils?


11/12/2008

Chemical composition of CKDsChemical composition of CKDs

High free lime content CKDsCKD-1

CKD-1 CKD-2 CKD-3 CKD-4 Chemical composition by

Weight (%)

Type I Cement

Free lime=13.85%Sulfate = 14.62Alkali = 3.72CKD-2Free lime=29 14%

XRF SiO2 12.18 16.42 11.91 15.39 20.48 Al2 O3 4.24 3.62 2.17 4.66 4.21 TiO2 0.22 0.23 0.15 0.57 0.36 P2O5 0.08 0.09 0.09 0.09 0.09 Fe2 O3 1.71 2.31 2.08 2.34 2.41 Free lime=29.14%

Sulfate = 12.69Alkali = 2.05

Low free lime content CKDsC 3

CaO 46.24 55.00 46.05 37.35 63.19MgO 1.24 2.68 2.2 2.10 4.00 Na2O 0.51 0.17 0.33 0.81 0.19 K2O 4.89 2.89 1.43 7.0 0.28 Na2O equiv. 3.72 2.05 1.27 5.36 0.373 Mn2O3 0.05 0.44 0.04 0.07 0.14 S O 0 04 0 03 0 07 0 02 0 04 CKD-3

Free lime=5.32%Sulfate = 4.21Alkali = 1.27CKD-4

SrO 0.04 0.03 0.07 0.02 0.04SO3 14.62 12.69 4.21 5.80 2.76 Cl 0.59 0.74 0.35 3.26 - LOI@ 750 14.22 3.92 29.63 27.65 1.76 free CaO ** 13.85 29.14 5.32 3.26 1.58 Water-soluble N O *

0.28 0.06 0.12 0.59 0.04 CKD 4Free lime=3.26%Sulfate = 5.80Alkali = 5.36

Na2O * Water-soluble K2O *

2.95 1.68 0.93 6.33 0.16


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Particle size Particle size distributiondistribution and surface areasand surface areas100

60

80

ller

40% S

ma

Type I cementCKD-1, SA = 0.41 m2/g

0

20CKD-2, SA = 0.30 m2/gCKD-3, SA = 0.36 m2/gCKD-4, SA = 0.34 m2/g

1 10 100 1000Particle diameter (micrometers)


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Morphology of CKD powdersMorphology of CKD powders

CKD-2CKD-1

Agglomerated particles with poorly

SEM analysis

Agglomerated particles with poorly defined shapes

presence of some spherical particles (fly ash)CKD-3

10 um 10 um

CKD-4

10 um10 um


11/12/2008

Morphology of hydrated CKD pastes (w/p=0.31)Morphology of hydrated CKD pastes (w/p=0.31)

CKD-1CKD-1CKD-1 CKD-3

Hydration changes the morphology of CKD powder. Hydration products in high free lime CKDs included needles of ettringite, occasional lath-shaped syngenite and sulfur-incorporating C-S-H-like phases

5 um

CKD 2CKD 2

5 um 5 um

incorporating C S H like phases

S

CKD-2

S

CKD-2 CKD-4

S

5 um5 um5 um

KCl


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Strength of compacted and hydrated CKD pastes Strength of compacted and hydrated CKD pastes (w/p=0.31)(w/p=0.31)( /p )( /p )

8000

10000

ngth

(kPa

CKD-1CKD-2

6000

8000

pres

sive

stren CKD-3

CKD-4

2000

4000on

fined

com

p

00 20 40 60 80 100

Curing period (days)

Unc

o

Compressive strength of CKDs compacted at constant moisture content


11/12/2008

Engineering properties of CKD treated claysEngineering properties of CKD treated clays

3 “Model” Clays,3 “Model” Clays,KaoliniteKaoliniteNN montmo illonitemontmo illoniteNaNa--montmorillonitemontmorilloniteCaCa--montmorillonitemontmorillonite

Engineering properties evaluated included:Engineering properties evaluated included:AtterbergAtterberg limitslimitspH valuespH valuesUnconfined compressive strength (UCS)Unconfined compressive strength (UCS)Stability and swellingStability and swellingStability and swellingStability and swelling

PhysicoPhysico--chemical effect of CKD addition were evaluated by:chemical effect of CKD addition were evaluated by:XRD, TGA, and SEM analysesXRD, TGA, and SEM analyses


11/12/2008

Effect of CKDs & lime on the Effect of CKDs & lime on the AtterbergAtterberg limitlimit--PIPI

400

450Na-montmorillonite

Changes in PI Values

250

300

350

nten

t (%

)

Changes in PI Values

150

200

50

Moi

stur

e co

0

50

100Kaolinite

kaoli

nite

CKD-1CKD-2CKD-3CKD-4

Lime 7

%

Na-mCKD-1CKD-2CKD-3CKD-4

lime 7

C


12

Effects of CKDs on the stressEffects of CKDs on the stress--strain behaviorstrain behavior

CKDCKD--treated treated kaolinitekaolinite clayclay

2000

1600

a).aa

CKD-1-15

CKD-2-15

800

1200

xial

stre

ss (k

P

CKD-3-15 CKD-4-15Compacted CKDs treated kaolinite clay samples were prepared using Harvard miniature compaction equipment at a

400

Ax

Kaolinite clay

miniature compaction equipment at a moisture content of 31%

Strength and stiffness of CKDs-treated kaolinite clay increased significantly

00 1 2 3 4 5 6 7 8 9 10 11 12

Axial strain (%)

compared to untreated clay

Strength and stiffness of CKD- treated Na-montmorillonite clay also showed the same trend

13

same trend.

Sulapha Peethamparan, Clarkson UniversityJan Olek, Purdue University

11/12/2008

UCS UCS developmentdevelopment in CKDin CKD--treated claystreated clays

5000

kaolinitekaolinite clay (nonclay (non-- expansive)expansive)

5000

NaNa--montmorillonitemontmorillonite clay clay (expansive)(expansive)

4000

5000

ve s

treng

th

CKD-1-25

4000

5000

h (k

Pa).a

a

CKD-1-25CKD-2-25CKD-3-25

2000

3000

d co

mpr

essi

v(k

Pa)

CKD 1 25CKD-2-25CKD-3-25CKD-4-25Kaolinite

2000

3000

pres

sive

stre

ngth CKD-4-25

Na-m

0

1000

Unc

onfin

ed

0

1000

Unc

onfin

ed c

omp

0 20 40 60 80 100


U

0 20 40 60 80 100U



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ASTM 4609

Visual swelling observation in CKDVisual swelling observation in CKD--treated treated NaNa--montmorillonitemontmorillonite clayclayyy

High free lime content CKD treated Na-montmorillonite

Low free lime content CKD- treated Na-montmorillonite

AA B A

B

The compacted samples slaked but no swelling was observed

A-compacted clay aloneB -Comp.CKD-2 treated clayA-compacted clay alone B -Comp.CKD-4

treated clay

15

No slaking or swelling was observed The compacted samples slaked but no swelling was observed


11/12/2008

Stability of CKDStability of CKD--treated clays exposed to watertreated clays exposed to water

No loss of strength was observed for CKD-2 treated kaolinite and there was a small reduction in the strength in the

kaolinite

6000

kPa).a

a

small reduction in the strength in the case of the CKD-1 treated kaolinite

CKD-3 and CKD-4 treated clay also retained more than 60% strength3000

4000

5000

essiv

e str

engt

h (k

unsoaked

soaked

No loss of strength was observed in the case of lime-treated kaolinite

Some loss of strength for Na-1000

2000

3000

onfin

ed c

ompr

e

Some loss of strength for Namontmorillonite clay treated with CKD-1 and CKD-2 when soaked in water for 2 days. No loss of strength was observed in the case of the lime-treated Na-

t ill it CKD 3 d CKD 4

0

CKD-1-25

CKD-2-25

CKD-3-25

CKD-4-25

kaoli

nite

Unc

o

montmorillonite. CKD-3 and CKD-4 treated clays slaked upon soaking in water

Stability-UCS of CKD-treated clay after soaking inwater for 2 days. (after a curing period of 90 days)

C C C C

Type of CKDs used for treating kaolinite


16

y ( g p y )

Comparison of UCS development in CKDComparison of UCS development in CKD--2 and lime 2 and lime treated claystreated claystreated claystreated clays

5000th

.. 5000

th...

NKaolinite clayNa-montmorillonite clay

3000

4000

essi

ve s

treng

ta)

CKD-2-25

Kaolinite

Li 7%

3000

4000

ress

ive

stre

ngt

a)...

Na-m

CKD-2-25

Lime 7%

Kaolinite clay

1000

2000

onfin

ed c

ompr

e(k

Pa Lime 7%

1000

2000

onfin

ed c

ompr

(kPa

00 20 40 60 80 100


Unc

o

00 20 40 60 80 100


Unc

o

Irrespective of the type of the clay, UCS of CKD-2 treated clay was substantially higher than that of the lime-treated clays


11/12/2008

CKDCKD--kaolinitekaolinite clay interactionclay interaction--SEM & EDSSEM & EDS

O Si

O AlSi

CaS

Compacted and cured kaolinite clay treatedClay flakes appeared in “book-like” stacks and it appeared that each clay flake is a part of a stack

Compacted and cured kaolinite clay treated with 25% CKD-2. The clay flake stacks “disagglomerated” - no preferential orientation of the flakes in “random structure”

18

stack


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CKDCKD--NaNa--montmorillonitemontmorillonite clay interactionclay interaction--SEM & EDSSEM & EDS

90 day old compacted untreated Na-montmorillonite Clay

A

B

Undulating fluffy film-like structure EDX pattern collected from the clay


11/12/2008

SummarySummary

All the CKDs enhanced the Atterberg limits, strength and stiffness of both the expansive and non expansive kaolinite

Strength of the CKD-treated clays were substantially higher compared to the lime-treated clays

All the CKD-treated kaolinite clay samples retained at least 50% strength y p gupon soaking in water. High free lime content CKDs retained more strength compared to low free lime content CKDs

The pozzolanic reaction is suggested as a significant mechanism in CKD-p gg gclay stabilization process (based on the observations made in this study)

Other mechanisms that may contribute to the significant improvement in the engineering properties of CKD treated clays compared to the lime g g p p y ptreated clays were identified as presence of ettringite and gypsum in the CKD-treated clays


11/12/2008

AcknowledgementsAcknowledgements

We would like to acknowledge the help of the following individuals

Prof. Sidney Diamond, Purdue UniversityJanet Lovell, Purdue UniversityyDebby Sherman, Purdue UniversityOscar Tavares, Lafarge North AmericaDr Laurent Barceló Lafarge CTSDr. Laurent Barceló, Lafarge CTS

11/012/08 21Sulapha Peethamparan, Clarkson University

Jan Olek, Purdue University

Documents

Utilization of Cement Kiln Dusts for Clay Soil Stabilizationwebpages.mcgill.ca/staff/Group3/aboyd1/web/Conferences... · 2013. 1. 9. · Utilization of Cement Kiln Dusts for Clay