Stabilization is being used for a variety of engineering works, one of the most common application being in the construction of road and airfield pavements, where the main objective is to increase the strength or stability of soil and to reduce the construction cost by making best use of the locally available material.The relevance of stabilization is to increase the bearing capacity of soil, decrease permeability and compressibility of soil, to control shrinkage and swelling etc. In this method carbonated magnesia is used for soil stabilization.

1. CARBONATING MAGNESIA
FOR SOIL STABILIZATION
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RELEVANCE OF STABILISATION
 To improve the engineering properties of soil
 Bearing capacity of soil may be inadequate
 Decrease permeability, compressibility
 To obtain adequate strength
 To control swelling and shrinkage

3. CHEMICAL STABILIZATION?
 The chemicals undergo various reactions
 Increases the binding property between the soil
particles
 changes surface molecular properties
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STABILIZING CHEMICALS
•Lime
• Calcium and sodium chloride
•Lignin
•Water proofers like siliconates ,
amines
•Natural and synthetic polymers
•Dispersants and aggregants

4.  An alternative solution for Stabilization by ordinary
Portland cement
Reasons
 Less energy consumption
 CO2 sequestration
 Higher compressive strength
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5. BASIC REACTIONS
MgO+H2O→Mg(OH) 2 (brucite)
Mg(OH) 2 +CO 2 +2H2O→ MgCO3.3H2O (Nesquehonite)
5 Mg(OH) 2 +4 CO 2 +H2O →(Mg) 5(CO3 ) 4(OH) 2 .5H2O
(dypingite)
5 Mg(OH) 2 +4 CO 2 →(Mg) 5(CO3 ) 4(OH) 2 .4H2O
(hydromagnesite)
•Expansive reactions (3.8 - 6.7)
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SCANNING
ELECTRON
MICROSCOPE
STUDIES
Courtesy:Yaolin Yi,
Martin Liska

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 Slightly clayey
silty sand (90%
sharp sand , 5%
kaolin clay, 5%
silica flour )
 organic clayey
silt (82% silica
flour ,15% kaolin
clay , 3% peat )
 Confining pressure 400 KPa
 CO 2 Pressures 200 Kpa,100 KPa, 50 KPa
 carbonation period 0.5-7 hours
LABORATORY SET -UP

8. Water content Vs Dry density
GRAPHS AND RESULTS
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Optimum water
content for maximum
dry density is more
than that of OPC –
Rapid hydration
Contd…

9. Water content Vs UCS
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optimum water
content for
maximum UCS
is lesser than
that of OPC –
enough
carbonation
Contd…

10. UCS Of MgO treated soil after a carbonation period of 3
Hours= UCS of PC stabilized soil at 28 days
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Lower the MgO content and Higher the
carbonation period cracks will be more
o Lower MgO ,Higher water content
o MgO impurities like dead burnt MgO

11. COLUMN INSTALATION & CARBONATION
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12. Column installation
 Laboratory scale auger set up
 MgO grout is pumped into grout inject
 Three switch travel stop mechanism
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•Auger penetration and
withdrawal-5.2 mm/sec
at 50 rpm
• grout pumped at 7.2
g/sec

13. Column carbonation
Method 1
•Pumping gaseous CO 2 through the auger
• Auger is connected to CO 2 canister
•Method 2
• perforated plastic pipe system
• More homogeneous carbonation
• Pipe Diameter 20 mm
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14. Real Life Applications
CARBONATION IS ACHIEVED THROUGH
 Deep mixing carbonation method
Injected reactive MgO powder is mixed with soil by
an auger followed by carbonation(Through perforated
pipe)
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DEEP MIXING CARBONATION
 Auger with hollow drill
 Mixing tool at the bottom
 Grout is passed through the drill rod

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CONCLUSION
 Adequately carbonated MgO treated soil in few hours reach 28 day
strength of PC stabilised soil
 Reactive MgO – A promising stabilisation binder through the
sequestration of CO 2
 Magnesium oxide has less environmental impact compared
with PC, in which the production process is conducted at a
temperature far less than that of PC.
 Compared to CaCO3 it is resistant to sulphate attack
 More stable than CaCO3

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REFERENCES
1. "Physical properties, Electrical Resistivity and strength characteristics of
Carbonated silty soil admixed with reactive Magnesia" - Devendra Narain Singh,
Guang Hua Cai: Canadian geotechnical journal(April 2015)
2. "Carbonating magnesia for soil stabilization" - Yaolin Yi, Martin Liska, Cise
Uniuer: Canadian geotechnical journal (June 2013)
3. "Soil stabilization using Lime: Advantages, Disadvantages and proposing a
potential alternative" -Ibtehaj Taha Jawad, Mohd Raihan Taha, Zaid Hameed
Majeed , Tanveer A .Khan: Research journal of applied sciences, Engineering and
technology (May 10,2014)
4. "Strength and deformation characteristics of carbonated reactive magnesia
treated silt soil" -CAI Guang-hua , LIU Song-Yu, DU Yan-jun, ZHANG Ding-wen,
ZHENG Xu:Central south University press and Springer (2015)
5. "Preliminary Laboratory-scale model Auger installation and testing of
carbonated soil-MgO columns" - Yaolin Yi, Martin Liska, Cise Uniuer:
Geotechnical testing journal (March 2013)

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