C. Denayer – Ms. Eng, MBA - April 2011 - Turkey

Soil Treatment with Lime

AN ECONOMICAL SOLUTION FOR SUBGRADE, SUB BASE, BASE & CAPPING LAYERS

LIME…The proven solution 2

1. Introduction

No bearing capacity

Clayey soils

Lime treated soil

• How lime is changing clay ?

Movie of 4 minutes

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Definitions for soil treatment for wet clayey soils

Soil Stabilization

(Platforms) Soil Improvement

(Earthworks)

Soil Treatment

Pavement

Wet clayey soils Lime treated soil

Road Base

Sub-Base

Sub-Grade

Earth Moving

Wear/Surface Layer

Reduce water content

improve ‘trafficability’ soils sensitive to water

Improve bearing capacity

Flexible durable embankment material

Road Base

Sub-Base

Sub-Grade

Earth Moving

Wear/Surface Layer

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Soil improvement by soil drying

• Soil drying is useful to create accessible

roads on the building site

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2. Soil suitability for lime treatment

• AASHTO M 145 soil classification based on :

particle size distribution, liquid limit & plasticity index.

• Limited organic content : < 2%

• Total content of sulphur salts : < 0,25%

COARSE-GRAINED SOILS

passing to 0,075 sieve ≤ 35%

FINE-GRAINED SOILS

passing to 0,075 sieve > 35%

CLASS A1 A3 A2

A4 A5 A6 A7

SUB-CLASS A1-a A1-b A2-4 A2-5 A2-6 A2-7

< 2.00 mm < 50

< 0,475 mm < 30 < 50 > 50 > 35 %

< 0,075 mm

< 15 < 25 < 10 < 35 < 35 < 35 < 35 > 35 > 35 > 35 > 35

LIQUID LIMIT

< 6 N.P.

< 40 > 40 < 40 > 40 < 40 > 40 < 40 > 40

PLASTICITY

INDEX < 10 < 10 > 10 > 10 < 10 < 10 > 10 > 10

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Solid Plastic Liquid

0 wP wL Water content

Liquid limit Plastic limit

Plasticity Index

• The consistency of a soil can range from (dry) solid to plastic and to liquid (wet).

• The water contents at which the consistency changes from one state to the next are

called consistency limits (or Atterberg limits) : Plastic Limit (PL) & Liquid Limit

(LL)

• Plasticity Index = PI = LL – PL = ....% -> PI more than 10

PL LL

Casagrande Method

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3. Immediate Lime Consumption

Adding CaO to wet clayey soils :

• SOIL DRYING :

CaO + H2O → Ca(OH)2 + 15,5 kCal

• FLOCCULATION :

Ca2+ and OH- ions

Increased pH of soil

• IMMEDIATE LIME CONSUMPTION

pH of soil > 12,4

Ca(OH)2

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4. Puzzolanic reactions

• Ca2+ + OH- + SiO2 -> CSH

(Calcium Silicate Hydrates)

• Ca2+ + OH- + Al2O3 -> CAH

(Calcium Aluminate Hydrates)

soil With lime

Picture: D. Little (Texas A/M)

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5. Proctor

• Soil + lime, by standard Proctor :

maximum dry density (MDD)

optimum moisture content (OMC)

compressive strength (28 days)

Dry

Volu

me

Mass

[k

N/m

3]

Moisture content [%]

Natural

soil

Soil + 4%

lime

Soil + 2%

lime

Compressive strength Class

≥ 0,2 MPa Rc 0,2

≥ 0,5 MPa Rc 0,5

≥ 1,0 MPa Rc 1,0

other declared value, but not less than 0,2 Mpa Rc DV

12 16 14 18 20

18

19

22 24 26

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6. Californian Bearing Ratio (CBR)

• Soil + lime, CBR-specimens :

After 7 days (air) + 4 days (water)

Volumetric swelling after 4 days (water)

CBR after 4 days soaking (or other longer specified) Class

≥ 15 CBR 15

≥ 20 and not less than the immediate bearing index CBR 20

≥ 30 and not less than the immediate bearing index CBR 30

≥ 20 and not less than the immediate bearing index CBR 40

≥ 30 and not less than the immediate bearing index CBR 50

declared value (but not less than 15) CBR DV

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7. Applications for civil engineering projects

• Airport

• High Speed Train

• Industrial Parks, Mall,

Business Parks

• Highway, Expressroad,…

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8. Execution

1. Preparation of soil

2. Spreading of lime

3. Mixing soil & lime

4. Compaction, grading & curing

Movie of 6 min.

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P

M = 110 MPa E 1

P

M = 35 MPa E 1

P

M = 17 MPa E 1

Pavement

Basement

Subbase

Subgrade

9. Control on site

• Deflection or deformation modulus

for :

Subgrade

Subbase

Basement

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10. Durability (Univ. of Kentucky - 2002)

• After more than 10 years : CBR-values

differences between soil & lime treated soil

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11. www.carmeusena.com (markets/construction)

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12. Stakeholders map

Nature : Clay soils

Specifiers : Min.of Transportation (MoT)

Cities administrations

Design companies

Road-contractors

Road basements: Costs savings

Time savings Environment savings

EN 14227-part 11

Soil treatment with lime – CL 90/80

EN 459 (part 1->3) Building lime

Turkish National

Guidelines

Road experts: Lime stabilization is

a proven solution

Specialized machinery : need for machinery

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13. Conclusion : sustainable proven solution

1. Cost saving :

Savings by design : reduced thickness of the road

Savings for aggregates purchase & transport costs

• 1 truck of lime replaces 70 to100 trucks of soil movement & new aggregates

Avoid landfill taxes

2. Time saving

Simplifies the process of execution

3. Environmental saving

Minimize vehicle movements and disturbance to the surrounding

Minimize waste generation and aggregate demand

700 MPa

Unstabilized subbaseStabilized subbase

100 MPa

700 MPa

28 MPa

Unstabilized subsoil Stabilized subsoil

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Thank you for your attention