Subgrade Soil Support and Stabilization -...

Co-PIs: Erol Tutumluer

Marshall R. Thompson

RA: H.S. Brar

Subgrade Soil Support

and Stabilization

O’HARE Airport Modernization Research Project

Research Progress Presentation – June 30, 2005

Introduction

� Subgrade performance is a key factor in the overall

pavement performance

National Airport

Pavement Test

Facility -

Atlantic City, NJ

� This project provides testing and analysis to establish

subgrade support and stabilization requirements

for O’Hare airport pavements

P154

P209

Introduction (cont’d)

� The preliminary concrete pavement design for the

O’Hare Modernization Program (OMP):

• 15 – 17 inches of PCC Surface

• 6-inch Hot Mix Asphalt Base

• 6-inch Asphalt Treated Permeable Base (!?)

• “Stabilized” Subgrade Zone (SSZ)

• Prepared Subgrade

� North Runway (9L-27R, 7,500 ft) paving is scheduled

first for the Spring 2006 (!?)

• Stockpiles of local soil on runway centerline (excavated

from the “Deep Pond” nearby)

• Primarily fill and cut areas

Research Objectives

� Consider pavement design inputs for subgrade

support

• Modulus of subgrade reaction, k

� Consider subgrade support and stabilization

requirements with respect to:

• Need for subgrade stabilization

• Stabilization admixture(s) stabilization

• Stabilization depth

� Estimate “subgrade support” for various

combinations of subgrade stabilization treatments and prepared subgrade conditions

Project Tasks

Task 1:

Establish the Best Demonstrated Available

Technology (BDAT) for subgrade soil evaluation

and stabilization (Ongoing)

Reports and publications collected & submitted as

“Technical Notes” on:

• Subgrade strength/stiffness evaluation techniques

• Subgrade stability requirements & IDOT Manual

• “Working platform” requirements for pavement

construction

Project Tasks

Task 2:

Evaluate currently available data for the subgrade test

sections constructed in the Fall of 2003 and the

necessity/usefulness of constructing additional subgrade treatment test sections at O’Hare

(Effort completed)

Plate load tests conducted (8/04) on the test sections:

• Plate 1: 12-inch stabilization/compaction – no admixture

• Plate 2: 12-inch quicklime fine (40 lb/yd2) & fly ash (80

lb/yd2) stabilization

• Plate 3: 12-inch quicklime fine stabilization (40 lb/yd2) √√√√ • Plate 4: 12-inch lime kiln dust stabilization (40 lb/yd2) √√√√

Plate Load Tests

Modulus of Subgrade

Reaction, k

Project Tasks

Task 3:

Advise OMP on current and future test section

monitoring and field test evaluation programs

(Effort completed)

Various field tests may be useful to characterize the

treated subgrade (OMP will arrange for testing):

• Dynamic Cone Penetrometer (8/04)

• Light-Weight Deflectometer (8/04)

• Clegg Hammer

• Geogauge

• Heavy Weight Deflectometer (HWD)

• Ground Penetrating Radar (GPR)

• Seismic Pavement Analyzer, SASW, etc.

Light-Weight

Deflectometer

Dynamic Cone

Penetrometer

Project Tasks

Task 4:

Evaluate currently available geotechnical/subgrade

data for the North Runway with emphasis on the

stockpiled “Deep Pond” soils. Recommend further soil sampling & testing to be conducted (by an OMP

designated testing firm) (Ongoing)

Routine tests to establish representative soils

existing for the runway subgrade

• Grain size distribution (including hydrometer)

• Atterberg limits (LL and PL for PI)

• Moisture-density-CBR

• PH value & calcareous content

• If needed, organic matter content

Preliminary Geotechnical Report

Soil sampling & testing conducted by Everest

Engineering on OMP Runway 9L-27R - October 2004

Boring

Logs

Atterberg limits

(LL and PL for PI)




Grain size distribution

(including hydrometer)




Moisture-density-CBR




Unconfined Compressive Strength, Qu

Soil Sampling: Dec. 04 – Feb. 05

Current scheduled soil sampling & testing from the R9L-27R

The Drilling Program

• Auger borings, 17 boreholes, MT-1 to MT-17

• 10’ to 45’ depths through fill & cut areas

• All reaching down to elev. 640’ in the natural subgrade

• 3 North of runway, 3 North edge of runway, 4 under

runway, 2 South edge of runway, 2 between runway and

taxiway, and 3 under taxiway

• SPT and soil sampling at 2.5’

• Moisture content, LL, PI, grain size distribution (%clay)

• Shelby tube samples at each location (638’ to 642’)

• At least 1 bucket for each major soil in each borehole

• Two 5-gallon buckets (60-70 lbs./bucket) for each

representative soil (composite sample) to test at the

University of Illinois

Project Tasks

Task 5:

Based on the data and information gathered in Task 4,

select (in consultation with OMP) the identified

representative soils and recommend an admixture stabilization program (Ongoing)

Tests to be conducted at the UIUC Advanced

Transportation Research and Engineering Laboratory

(ATREL) on both untreated & treated soils

• Moisture-Density-CBR

• Unconfined Compressive Strength

• Resilient Modulus

• Permanent Deformation @ 6-psi deviator stress

Project Challenges

� Proper sampling of the R9L-27R stockpiled soils

� Selecting & identifying representative soil samples

� Adequately characterizing the representative soil samples by conducting tests at the UIUC ATREL for

• Moisture-Density-CBR

• Unconfined Compressive Strength

• Resilient Modulus

• Permanent Deformation @ 6-psi deviator stress

University of Illinois Laboratory

Testing Program at ATREL

Advanced Transportation Research & Engineering Laboratory (ATREL)

Location Bucket No. Depth Soil Description

% Clay LL PI

% Silt pH

Carbonate Reaction

Under N edge of Taxiway 48 6'-10' Gray SILTY SAND 11.9 NP NP 21.5 7.8 Weak

North of Runway 1 1'-3' Brown Sandy Sil t 16 NP NP 47.4 7.4 weak to strong

Under Taxiway 57 15'-18' Gray SILTY SAND 17.4 NP NP 21.5 7.8 Weak

N edge of Runway 20 5'-10' Gray SILTY CLAY with Sand 17.6 22 6 54.8 7.8 Strong

Under Taxiway 53 22'-26' Gray SANDY SILT 18.3 NP NP 42.6 8 Weak

North of Runway 17 1'-5' Brown and Gray SANDY LEAN CLAY 19.2 30 17 35.4 7.2 Weak to Strong

Under Runway 13 3'-6' Gray SANDY SILT CLAY 21.1 22 6 44.2 7.2 Weak to Strong

Under S edge of Runway 43 1'-4' Gray LEAN CLAY with sand 22.1 24 8 52.4 7.9 Strong

Under N edge of Runway 49 24'-28' Gray LEAN CLAY with sand 22.1 31 12 51.2 7.9 Strong

Under Taxiway 54 29'-33' Gray SANDY LEAN CLAY 22.1 30 11 39.7 8.1 Strong

North of Runway 9 3'-6' Brown and Gray SANDY LEAN CLAY 22.2 22 9 45.5 7.6 Weak to Strong

North of Runway 2 6'-10' Gray SANDY LEAN CLAY 22.5 24 11 46.8 6.3 Weak

Under Taxiway 52 6'-10' Gray SANDY LEAN CLAY 22.8 25 8 44.5 7.5 Strong

Under Taxiway 51 2'-6' Gray LEAN CLAY with sand 23.5 27 12 49.9 7.7 Strong

b/w Runway & taxiway 41 16'-20' Gray SANDY LEAN CLAY 23.7 24 8 43.7 7.1 Weak to Strong

Under S edge of Runway 44 8'-12' Gray SANDY LEAN CLAY 23.7 24 8 42.9 8 Strong

Under N edge of Runway 5 1'-5' Brown and Gray LEAN CLAY with Sand 25.1 26 10 53.8 7.1 Weak to Strong

Under N edge of Taxiway 50 33'-36' Gray SANDY LEAN CLAY 25.3 28 10 41.6 8 Weak

Under Runway 22 1'-5' Brown and Gray LEAN CLAY with Sand 25.4 29 13 50.8 7.7 Weak to Strong

b/w Runway & taxiway 42 26'-30' Gray LEAN CLAY with sand 25.6 30 12 46.8 7.8 Strong

North of Runway 11 16'-20' Gray LEAN CLAY with Sand 25.7 26 10 56.4 6.9 Weak

62 Buckets of OMP Soils Arrived at

ATREL from the Drilling Program

MARCH 2005

North of Runway 18 18'-23' Gray LEAN CLAY with sand 25.7 23 8 46.3 7.7 Strong

Under S edge of Runway 28 1'-5' Gray LEAN CLAY with Sand 25.8 23 8 45.3 7.4 Strong

North of Runway 10 8'-12' Gray LEAN CLAY with Sand 27.1 25 10 51.5 7.5 Strong

Under S edge of Runway 45 24'-28' Gray LEAN CLAY with sand 27.6 27 10 46.1 8.2 Strong

Under S edge of Runway 29 13'-18' Gray LEAN CLAY with Sand 27.7 23 8 49.3 8 Strong

Under Runway 33 8'-12' Gray LEAN CLAY with Sand 27.9 26 10 44.7 8.5 Strong

b/w Runway & taxiway 39 2'-6' Gray SANDY LEAN CLAY 28.2 28 9 41.6 8.7 Strong

Under Runway 26 0'-3' Black,Brown and Gray SANDY LEAN CLAY 28.7 41 23 33 8.4 Weak

b/w Runway & taxiway 40 8'-12' Gray LEAN CLAY with sand 28.9 28 10 46.3 8.4 Strong

Under N edge of Taxiway 47 1'-5' Gray LEAN CLAY with sand 29 33 13 43.2 7.5 Strong


b/w Runway & taxiway 36 1'-5' Gray LEAN CLAY with Sand 29.4 24 11 39.3 7.5 Strong

Under Runway 14 10'-15' Gray LEAN CLAY with sand 29.5 25 10 51.7 7.7 Strong

North of Runway 3 16'20' Gray LEAN CLAY with sand 29.7 32 17 50 7.6 Strong

b/w Runway & taxiway 37 15'-20' Brown and Gray SANDY LEAN CLAY 30.9 27 13 42.7 8.1 Strong

Under S edge of Runway 30 28'-32' Gray LEAN CLAY with Sand 31 27 12 46 8.2 Strong

Under N edge of Runway 6 11'-15' Gray LEAN CLAY with sand 31.1 27 13 49.3 7.4 Strong

Under Runway 23 10'-13' Brown and Gray LEAN CLAY with Sand 31.5 29 14 44.5 8.6 Strong

North of Runway 19 28'-33' Brown and Gray LEAN CLAY with Sand 31.7 29 13 40.1 7.8 Weak


b/w Runway & taxiway 38 25'-30' Gray LEAN CLAY with Sand 31.9 31 16 44.3 8 Strong

North of Runway 4 22'-27' Gray LEAN CLAY with sand 32.2 34 17 45.6 6.5 Weak

Location Bucket No. Depth Soil Description

% Clay LL PI

% Silt pH

Carbonate Reaction

62 Buckets of OMP Soils Arrived at

ATREL from the Drilling Program- cont’d

MARCH 2005

Boring No.

Bucket No. Depth Soil Description

Clay (%)

LL (%)

PI (%)

Silt (%)

GROUP 1

MT 14 20 5'-10' Gray SILTY CLAY with Sand 17.6 22 6 54.8

MT 16 17 1'-5' Brown and Gray SANDY LEAN CLAY 19.2 30 17 35.4

MT 4 43 1'-4' Gray LEAN CLAY with sand 22.1 24 8 52.4

MT 3 54 29'-33' Gray SANDY LEAN CLAY 22.1 30 11 39.7

GROUP 2


MT 3 51 2'-6' Gray LEAN CLAY with sand 23.5 27 12 49.9



Grouping of Soils at ATREL

Grouping done primarily according to % clay content!..

Boring No.

Bucket No. Depth Soil Description

Clay (%)

LL (%)

PI (%)

Silt (%)

GROUP 3

MT 5 47 1'-5' Gray LEAN CLAY with sand 29 33 13 43.2

MT 15 32 1'-5' Gray LEAN CLAY with Sand 29.2 24 9 41.4

MT 10 36 1'-5' Gray LEAN CLAY with Sand 29.4 24 11 39.3

MT 13 3 16'-20' Gray LEAN CLAY with sand 29.7 32 17 50

GROUP 4

MT 17 24 18'-21'

Brown and Gray LEAN CLAY with Sand 39.4 41 24 39.7

MT 8 16 30'-34'


MT 12 12 30'-35'


MT 6 27 6'-10'

Brown and Gray LEAN CLAY with Sand 43.7 44 18 38

Grouping of Soils at ATREL

Admixture Types / Sources

� Carmeuse (potential supplier)

�South Chicago (dolomitic lime)

�Buffington, IN (high calcium lime)

� Lime types

�Lime Kiln Dust (LKD)

�Quicklime fines

� Buffington is the primary source

(We will work with this & confirm with S. Chicago)

so far used

in lime treatment

Test Specimen Preparation

Air Drying Pulverizing

Mixing

Moisture-

Density-

CBR Results CBR

(ASTM D1883)

Proctor

Compaction

(ASTM D698,

D1557)

Untreated

Moisture-Density

0 % Lime

5 % Lime

W (%) Dry Density ( pcf ) W (%) Dry Density ( pcf )

10.2 117.89 10.7 110.44

11.9 121.72 13.2 114.30

14.3 118.84 16.3 112.97

16.1 113.27 19.3 107.57

Group 1 Results

0 % Lime

5 % Lime

W (%) CBR W (%) CBR

10.1 44 10.5 77

11.4 22 13.1 61

13.8 5 15.8 16

15.8 2 19.1 5

California Bearing Ratio (CBR)

Group 1 Results

100

105

110

115

120

125

8 10 12 14 16 18 20

Moisture %

Density (pcf)

0% Lime

5% Lime

OMC=12.1%

OMC=13.8%

Group 1 Results

0

10

20

30

40

50

60

70

80

90

10 12 14 16 18 20

Moisture %

CBR 0% Lim e

5% Lime

OMC=12.1%

OMC=13.8%

0 % Lime

5 % Lime


12.4 115.36 14 109.81

14.1 119.06 16 114.98

15.8 114.84 18.9 110.23

18.3 108.74 22.4 102.34

Moisture-Density

Group 2 Results

0 % Lime

5 % Lime

W (%) CBR W (%) CBR

11.7 26 13.2 55

13.4 15 15.9 39

15.7 4 18.6 10

17.6 1 22 4


Group 2 Results

95

100

105

110

115

120

125

10 13 16 19 22 25

Moisture Content %

Dry Density (pcf)

OMC =14.1%

OMC=16%

0

10

20

30

40

50

60

10 12 14 16 18 20 22 24

CBR

0% Lime

5% Lime

OMC = 16%

OMC = 14.1%

Group 2 Results

0 % Lime

5 % Lime


12.3 112.85 13.6 107.00

14.4 117.61 17.1 107.65

16.4 113.21 19.8 107.53

18.1 108.75 22.7 102.39

Moisture-Density

Group 3 Results

0 % Lime

5 % Lime

W (%) CBR W (%) CBR

11.9 27 13.3 55

13.9 13 16.1 35

15.8 4 19.2 13

18 1 22.2 6


Group 3 Results

Group 3 Results

100.00

104.00

108.00

112.00

116.00

120.00

10 12 14 16 18 20 22 24

Moisture Content %

Density (pcf)

0% Lime

5% LimeOMC=18.8 %

OMC=14.4 %

0

10

20

30

40

50

60

10 12 14 16 18 20 22 24

CBR 0% Lime

5% LimeOMC=18.8 %

OMC=14.4 %

0 % Lime

5 % Lime


17.2 102.97 16.9 96.91

18.7 105.26 20.0 97.38

21.2 103.77 23.4 98.00

22.9 100.39 26.5 94.30

Moisture-Density

Group 4 Results

0 % Lime

5 % Lime

W (%) CBR W (%) CBR

16.0 26 16.7 41

18.7 19 19.6 34

20.6 10 22.4 25

22.3 6 26.3 12


Group 4 Results

Group 4 Results

92.00

96.00

100.00

104.00

108.00

14 17 20 23 26 29

Moisture %

Density (pcf)

0% Lime

5% Lime

OMC= 18.8 %

OMC = 22.8 %

0

5

10

15

20

25

30

35

40

45

14 16 18 20 22 24 26 28

CBR 0% Lime

5% Lime

OMC = 18.8 %

OMC= 22.8 %

Unconfined Compressive

Strength Test Results

σ

C = (σσσσ1f)/2

= Qu/2

τ

σσσσ1 σσσσ1f σσσσ3 = 0

σσσσd = σσσσ1 – σσσσ3(=0)

failure

Cohesive Soils (c, φφφφ=0)

(ASTM D2166)

Group

No.

OMC

(%)

Water Content

(%)

Dry Density

(pcf)

UCS

(psi)

1

12.1

12.3

122.5

80

2

14.1

14

118.7

44

3

14.4

14.2

118.7

60

4

18.8

19.5

108.2

74

UCS without Lime

0

20

40

60

80

100

120

0 2.5 5 7.5 10 12.5 15

Axial Strain, %

Axial Stress, psi

Group 1

Group 2

Group 3

Group 4

UCS Without Lime

Group

No.

OMC

(%)

Sample

No.

Water

Content (%)

Dry Density

( pcf )

UCS

(psi)

Avg. UCS

(psi)

1

13.8

1 13.3 106.64 109

119 2 13.7 108.5 120

3 13.8 109.49 128

2

16

1 15.3 116.82 202

184 2 15 116.11 177

3 15 115.36 174

3

18.8

1 17.5 110.43 129

138 2 17.9 110.48 146

3 17.9 110.50 138

4

22.8

1 22.1 98.2 197

217 2 22.2 98.4 233

3 22.1 97.7 221

UCS with 5% Lime

0

20

40

60

80

100

120

140

0 0.5 1 1.5 2Axial Strain, %

Axial Stress, psi

Sample 1

Sample 2

Sample 3

Group 1 with 5% Lime

0

50

100

150

200

250

0 0.5 1 1.5 2 2.5

Axial Strain, %

Axial Stress, psi

Sample 1Sample 2Sample 3

Group 4 with 5% Lime

Group

No.

UCS with Lime

Qulime

(psi)

UCS without Lime

Qu

(psi)

Lime Reactivity

= (Qulime - Qu) (psi)

1 119 80 39

2 184 44 140

3 138 60 78

4 217 74 143

Lime Reactivity

Resilient Modulus (MR) Testing

MR = resilient modulus

= σσσσd / εεεεr

σσσσd : Deviator stress

εεεεr : recoverable strain

Conditioning: 200 load applications at σ3 = 0, σd = 41 kPa

Testing: 100 load applications σσσσd = 14, 28, 41, 55, 69, 83, 96, 110 kPa

σd

Unconfined:

σ3 = 0

2-in. in φφφφ

MR Tests – Soil Samples

Cylindrical specimens, 2 in. φ by 4 in. high

Undisturbed soil samples – Shelby tube (φ = 2.8, 4 in.)

0

4

8

12

16

20

24

28

0 2 4 6 8 10 12 14 16 18

APPLIED DEVIATOR STRESS σσσσ d (psi)

RESILIENT M

ODULUS M

R (ksi) A-4 soil at OMC

A-4 soil at OMC+3

M R = - 2.21248 σσσσ d + 29.696 R 2 = 0.9497

M R = - 0.6274 σσσσ d + 1820 R 2 = 0.6617

M R = - 0.4203 σσσσ d + 8.351 R 2 = 0.8715

M R = 0.0408 σσσσ d + 4.9412

R 2 = 0.8796

Typical MR Characterization

Bilinear or

Arithmetic

Model

Greensboro, NC Airport

Subgrade Soils

0

2

4

6

8

10

12

14

16

18

20

22

24

0 2 4 6 8 10 12 14 16 18

Deviator Stress, psi

Resilient modulus, ksi

Group 1 MR Test Results

Eri


0

2

4

6

8

10

12

14

16

18

20

0 2 4 6 8 10 12 14 16 18



Eri

0

2

4

6

8

10

12

14

16

18

20

22

24

26

0 2 4 6 8 10 12 14 16 18



Sample 1


Eri


0

2

4

6

8

10

12

14

16

18

20

22

24

0 2 4 6 8 10 12 14 16 18



Sample 2

Eri

0

2

4

6

8

10

12

14

16

18

20

22

24

0 2 4 6 8 10 12 14 16 18



Sample 1


Eri

0

3

6

9

12

15

18

21

24

0 2 4 6 8 10 12 14 16 18



Sample 2


Eri

Summary of Results (1)

Moisture Density CBR Tests:

� Optimum moisture contents of the natural soils were always lower

those of the same soils treated with 5% lime kiln dust (LKD)

� Similarly, maximum dry densities were always higher for the

natural soils without lime treatment

� The unsoaked CBR values obtained from testing the compacted

specimens tend to drop sharply after the optimum moisture contents for the soils without lime

� The treated soils with 5% lime always gave much higher unsoaked CBR values than the natural soils with no lime

� In general, the 5% lime treatment was effective for increasing

sufficiently the strength of the North Runway 9L-37R subgrade

soils tested

Summary of Results (2)

Unconfined Compressive Strength Tests:

� Large increases in unconfined compressive strengths observed for

all groups when 5% lime was added

� Lime reactivity (Qu lime treated −−−− Qu natural) is greater than 50 psi

for all the groups except for Group 1

� Minimum lime treated Qu = 119 psi was recorded for Group 1 soils

with the lowest clay contents & the least reactivity with lime

Resilient Modulus (MR) Tests:

� MR decreased with increasing applied deviator stresses;

typical stress-softening fine grained soil behavior

� All soil groups tested at the OMC gave high MR values at 6

psi deviator stress, in the range of Eri = 15-20 ksi

Conclusion

From the results of all tests performed, “Green Light” is

given to the 5% lime kiln dust treatment which seems to

be working quite well in increasing the soil strengths

and, therefore, is suggested as the stabilization choice

for the subgrade soils at the new North Runway 9L-27R

of O’Hare International Airport

Project Deliverables

� Technical Notes have been prepared and submitted to the OMP throughout the project duration to communicate specific findings and

recommendations to OMP engineers � TN5: K-150 Considerations for RW 9-27

� TN6: Subgrade Strength/Stiffness Evaluation

� TN7: “Working Platform” Requirements for Pavement Construction

� TN8: Subgrade Stability Manual (IDOT) � TM13: Moisture Limitations for Lime Stabilization

� TN14: Admixture Stabilization (Lime Treatment of Subgrades)

� Several of the Project Tasks have been pursued simultaneously and

coordinated with OMP

� A Report summarizing Laboratory Soil Test Program has been prepared.

More soil-lime testing will be conducted with different lime sources

� A Final Report will be prepared at the end of the one-year study

(September/October 2005)

� We will continue to work with OMP on future subgrade soil support and

stabilization needs for other runways/taxiways

Subgrade Soil Support and Stabilization -...

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