Effectiveness ofVarious Lime Products for

Soil Drying

Larry Cole, P.E.Carmeuse Lime Company

LIME 2

North America

Wet, Unstable Subgrade Material

Poor engineering characteristics when wet (low strength, difficult construction, potential for pumping)

LIME 3

North America

Wet Site Conditions

Delays embankment construction (multiple lifts)

LIME 4

North America

Wet, Unstable Soil

LIME 5

North America

What to Do?

Wait for Natural Drying -• Low investment• Slow

- Lost time = lost $• More rain• Large uncertainty• No soil improvement

LIME 6

North America

What to Do?

Remove and Replace -• Very effective• Costly• Slow• Disposal issues • Impacts surrounding

community

LIME 7

North America

What to Do?

Lime Treatment -• Very effective• Acts rapidly•Uses existing soil – no

disposal issues• Improves soil properties

• Reduces plasticity• Increase strength

- Short term- Long term

• Cost effective

LIME 8

North America

CaCO3 + MgCO3 CaO + MgO + CO2

CaO + MgO --- “Quicklime”

LIME 9

North America

Lime Products for Treating Soil

Quicklime - (CaO and MgO)

1. High Calcium Quicklime

2. Dolomitic Quicklime

3. Hydrated Lime - Ca(OH2)

Lime Kiln Dust:4. High Calcium Lime Kiln Dust

5. Dolomitic Lime Kiln Dust

- Available CaO 18% - 30%

LIME 10

North America

Lime Hydration

Quicklime + Water Hydrated Lime

CaO + H2O Ca(OH)2

Calcium Oxide + Water Calcium Hydroxide

LIME 11

North America

Soil Drying

Quicklime + Water Hydrated Lime

CaO + MgO + H2O Ca(OH)2 + Mg(OH)2

Quicklime absorbs 40%of its weight in water.

Hydration lets off heat,Driving off water thru Increased evaporation.

LIME 12

North America

98

100

102

104

106

108

10 15 20 25

OMC = 17%

Dry

Density (

PC

F)

Lime Modified Soils have a New Optimum Moisture Content

LIME 13

North America

92

94

96

98

100

102

104

106

108

10 15 20 25 30

No Lime

3% Lime

OMC = 17%

Dry

Density (

PC

F)

OMC = 21%

Lime Modified Soils have a New, Higher Optimum Moisture Content

LIME 14

North America

Effective Change of Moisture Content

Net Effective Change of 3% Lime

In Moisture Content for Compaction:

Decrease in Moisture Content: 3%

New-Higher OMC: 4%

Net Effective Change: 7%

LIME 15

North America

Lime Products for Treating Soil

1. High Calcium Quicklime

3. Hydrated Lime - Ca(OH2)

4. High Calcium Lime Kiln Dust

2. Dolomitic Quicklime

5. Dolomitic Lime Kiln Dust

LIME 16

North America

Soils Evaluated

1. Chicago – O-HareP.I. = 7 (SC, A-2-6) OMC = 12.2%

2. US-30 – OhioP.I. = 24 (CL, A-6) OMC = 15.9%

3. Near Dulles Airport, VAP.I. = 26 (CL, A-6) OMC = 20.6%

4. Point Potomac, VAP.I = 37 (CH, A-7-6) OMC = 24.8%

LIME 17

North America

0

1

2

3

4

5

6

7

8

PI = 7 PI = 22 PI = 26 PI = 37

4% High Cal Quicklime

4% Dolomitic Quicklime

4% Hydrated Lime

4% Hi Cal LKD

4% Dolomitic LKD

Moisture Decrease 4 Hours After Mixing

LIME 21

North America

-1

1

3

5

7

9

11

13

15

PI = 7 PI = 22 PI = 26 PI = 37

4% High Cal Quicklime4% Dolomitic Quicklime4% Hydrated Lime4% Hi Cal LKD 4% Dolomitic LKD

Net Effective Change - 24 Hours After Mixing (OMC Increase plus Moisture Decrease)

LIME 22

North America

0

1

2

3

4

5

6

7

8

Hi Cal Quicklime Dolomitic Quicklime Hydrated Lime Hi Cal LKD Dolo Lkd

Average Effectiveness for “Soil Drying”(OMC Increase plus Moisture Decrease)For All Four Soils – 24 hrs After Mixing

OM

C I

ncr

ease

plu

s M

ois

ture

Decr

ease

Soil Initial Moisture Content at 8% above OMC

LIME 23

North America

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

PI = 7 PI = 22 PI = 26 PI = 37

4% High Cal Quicklime4% Dolomitic Quicklime4% Hydrated Lime4% Hi Cal LKD 4% Dolomitic LKD

% of 24-hr Moisture Reduction and OMC IncreaseThat Occurs in the First 4 Hours

LIME 24

North America

0

1

2

3

4

5

6

7

8

Soil A Soil B Soil C Soil D

With Second Mixing at 24-hrs

No Second Mixing at 24-hrs

Effect of Remixing on Soil Drying(24 hours After Initial Mixing

With 4% High Calcium Quicklime)

Decr

ease

in S

oil

Mois

ture

Conte

nt

Soil Initial Moisture Content at 8% above OMC