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?
5Sulapha Peethamparan, Clarkson UniversityJan Olek, Purdue University
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
6Sulapha Peethamparan, Clarkson UniversityJan Olek, Purdue University
11/12/2008
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)
7Sulapha Peethamparan, Clarkson UniversityJan Olek, Purdue University
11/12/2008
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
8Sulapha Peethamparan, Clarkson UniversityJan Olek, Purdue University
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
9Sulapha Peethamparan, Clarkson UniversityJan Olek, Purdue University
11/12/2008
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
10Sulapha Peethamparan, Clarkson UniversityJan Olek, Purdue University
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
11Sulapha Peethamparan, Clarkson UniversityJan Olek, Purdue University
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
11/12/2008 Sulapha Peethamparan, Clarkson UniversityJan Olek, Purdue University
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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
Curing period (days)
U
0 20 40 60 80 100U
Curing period (days)
14Sulapha Peethamparan, Clarkson UniversityJan Olek, Purdue University
11/12/2008
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
Sulapha Peethamparan, Clarkson UniversityJan Olek, Purdue University
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
11/12/2008 Sulapha Peethamparan, Clarkson UniversityJan Olek, Purdue University
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
Curing period (days)
Unc
o
00 20 40 60 80 100
Curing period (days)
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
17Sulapha Peethamparan, Clarkson UniversityJan Olek, Purdue University
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
Sulapha Peethamparan, Clarkson UniversityJan Olek, Purdue University
11/12/2008
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
19Sulapha Peethamparan, Clarkson UniversityJan Olek, Purdue University
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
20Sulapha Peethamparan, Clarkson UniversityJan Olek, Purdue University
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