05 - soil stabilization
TRANSCRIPT
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Soil Stabilization
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Soil Stabilizers Quicklime: CaO
Lime Kiln Dust: CaO Hydrated Lime: Ca(OH)2
Cement: CaO, SiO2, Al2O3 Cement Kiln Dust: CaO, SiO2, Al2O3
Class C Fly Ash: CaO, SiO2, Al2O3 Class F Fly Ash: SiO2, Al2O3
Source: PCA R&D Serial No. 2435
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Lime Stabilization Flocculate and agglomerate clay particles
by replacing monovalent cations such asNa+ with Ca++
Cement clay particles together by creatingCaCO3 from CaO plus atmospheric CO2 Cement clay particles together by creating
a pozzolanic reaction between CaO, SiO2,and Al2O3
Source: PCA R&D Serial No. 2435
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Clay Mineralogy
Source: hydram.epfl.ch/VICAIRE/mod_3/chapt_1/text.htm
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Clay Mineralogy
Source: hydram.epfl.ch/VICAIRE/mod_3/chapt_1/text.htm
Kaolinite Illite Smectite
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10 - 300.2 - 2.00.05 - 0.2
Kaolinite
50 - 1000.2 - 2.00.01 - 0.1
Illite
200 - 8000.1 - 0.50.001 - 0.01
Montmorillonite
SpecificSurface(m2/g)
TypicalDiameter
(m)
TypicalThickness
(m)EdgeView
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Clay Mineralogy
Source: hydram.epfl.ch/VICAIRE/mod_3/chapt_1/text.htm
Dispersed &Deflocculated
Dispersed &
Flocculated
Agglomerated &Flocculated
Agglomerated &Deflocculated
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Lime Stabilization Agglomerate clay particles by replacing
monovalent cations such as Na+ with Ca++
Cement clay particles together by creating
CaCO3 from CaO plus atmospheric CO2 Cement clay particles together by creating
a pozzolanic reaction between CaO, SiO2,
and Al2O3
Source: PCA R&D Serial No. 2435
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A Bit of Chemistry
When limestone (calcium carbonate) isheated above 825C, carbon dioxide isdriven off, leaving lime (calcium oxide):
3 2825
heat
CCaCO CaO CO
> +
This process is called calcination.
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A Bit of Chemistry
The lime is usually mixed with water toform slaked lime(calcium hydroxide)
2 2( )CaO H O Ca OH heat + +
which is more stable because the limesthirst for water has been slaked.
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A Bit of Chemistry
Carbon dioxide in the air can combinewith the slaked lime to essentially formnew limestone (calcium carbonate)
+ 22 3 2( )CO
Ca OH CaCO H O
This was a form of ancient cement.
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Lime Stabilization Agglomerate clay particles by replacing
monovalent cations such as Na+ with Ca++
Cement clay particles together by creating
CaCO3 from CaO plus atmospheric CO2 Cement clay particles together by creating
a pozzolanic reaction between CaO, SiO2,
and Al2O3
Source: PCA R&D Serial No. 2435
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Cement Hydration
+ + +CS H CSH CH heat
calcium silicate
water
calcium silicate hydrate gel
calcium hydroxide crystals
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Pozzalanic Reaction
+ + +CS H CSH CH heat
CH S CSH +
pozzolan
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Treatment Selection
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Unified Soil Classification System
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Casagrandes Plasticity Chart
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Selection Guide
Source: Army TM 5-822-14
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Selection Guide
Source: Army TM 5-822-14
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Selection Guide
Source: Army TM 5-822-14
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AASHTO Soil Classification
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Soil Modification Guide
Source: http://www.okladot.state.ok.us/materials/pdfs-ohdl/ohdl51.pdf
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Soil Stabilization Guide
Source: http://www.okladot.state.ok.us/materials/pdfs-ohdl/ohdl50.pdf