1. Subgrade Soil Support and Stabilization
O’HARE Airport Modernization Research Project
Co-PIs: Erol Tutumluer Marshall R. Thompson
RA: H.S. Brar

2. Introduction
Subgrade performance is a key factor in the overall pavement performance
P154
P209
National Airport
Pavement Test
Facility -
Atlantic City, NJ
Persistence length is the length which the polymer looks like straight.
-e : one negative charge
This project provides testing and analysis to establish subgrade support and stabilization requirements for O’Hare airport pavements

3. 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
Persistence length is the length which the polymer looks like straight.
-e : one negative charge

4. 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
Persistence length is the length which the polymer looks like straight.
-e : one negative charge

5. 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
Persistence length is the length which the polymer looks like straight.
-e : one negative charge

6. 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) 
Persistence length is the length which the polymer looks like straight.
-e : one negative charge

7. Modulus of Subgrade Reaction, k
Plate Load Tests
Persistence length is the length which the polymer looks like straight.
-e : one negative charge
Modulus of Subgrade
Reaction, k

8. 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.
Persistence length is the length which the polymer looks like straight.
-e : one negative charge

9. Dynamic Cone Penetrometer
Light-Weight
Deflectometer
Persistence length is the length which the polymer looks like straight.
-e : one negative charge

10. 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
Persistence length is the length which the polymer looks like straight.
-e : one negative charge

11. Preliminary Geotechnical Report
Soil sampling & testing conducted by Everest Engineering on OMP Runway 9L-27R - October 2004
Atterberg limits
(LL and PL for PI)
Persistence length is the length which the polymer looks like straight.
-e : one negative charge
Boring
Logs

12. Preliminary Geotechnical Report
Soil sampling & testing conducted by Everest Engineering on OMP Runway 9L-27R - October 2004
Grain size distribution
(including hydrometer)
Persistence length is the length which the polymer looks like straight.
-e : one negative charge

13. Preliminary Geotechnical Report
Soil sampling & testing conducted by Everest Engineering on OMP Runway 9L-27R - October 2004
Moisture-density-CBR
Persistence length is the length which the polymer looks like straight.
-e : one negative charge

14. Preliminary Geotechnical Report
Soil sampling & testing conducted by Everest Engineering on OMP Runway 9L-27R - October 2004
Persistence length is the length which the polymer looks like straight.
-e : one negative charge
Unconfined Compressive Strength, Qu

15. 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

16. Soil Sampling: Dec. 04 – Feb. 05
University of Illinois input/review – The Drilling Program
Laboratory Testing Needs
Check the pH of the soil samples
Check the samples for “free carbonates” by squirting with 10% HCl solution
How are the SPT samples handled?
“N” counts will be helpful in assessing the mobility characteristics (sinkage/rolling resistance) of the stockpiled soils
What tests are conducted with the Shelby tube samples?
Undisturbed samples obtained from the natural subgrade (finished subgrade elevation) will be best utilized to run unconfined compressive strength and resilient modulus tests

17. 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 6-psi deviator stress
Persistence length is the length which the polymer looks like straight.
-e : one negative charge

18. 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 6-psi deviator stress
Persistence length is the length which the polymer looks like straight.
-e : one negative charge

19. University of Illinois Laboratory Testing Program at ATREL
Advanced Transportation Research & Engineering Laboratory (ATREL)

20. 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)

21. Proctor Compaction (ASTM D698, D1557)
Moisture-
Density-
CBR
CBR
(ASTM D1883)
Untreated
Proctor Compaction (ASTM D698, D1557)

22. Moisture-Density-CBR
Lime treated
Lime treated

23. Moisture-Density-CBR
Treated
LKD: Lime Kiln Dust

24. Unconfined Compressive Strength
sd = s1 – s3(=0)
failure
C = (s1f)/2
= Qu/2
s3 = 0 s1
s1f s
Cohesive Soils (c, f=0)
(ASTM D2166)

25. Typical Unconfined s-e Data60
Dupont Clay
MC = 23 % 50
DD = pcf
CBR = 14
Qu = unconfined
compressive
strength
= peak s1 10 20 30 40
MC = 26 %
DD = 98 pcf
CBR = 8
Axial Stress, psi
MC = 28.5 %
DD = 93.5 pcf
CBR = 4
MC = 30.5 %
DD = 92.5 pcf
CBR = 2.5 5 10 15
Axial Strain, %

26. Deviator Stress at Failure

27. Deviator Stress at Failure
Effect of Curing

28. Resilient Modulus Testing sd
Unconfined:
s3 = 0
2-in. in f
MR = resilient modulus
= sd / er
sd : Deviator stress
er : recoverable strain
Conditioning: 200 load applications at s3 = 0, sd = 41 kPa
Testing: 100 load applications
sd = 14, 28, 41, 55, 69, 83, 96, 110 kPa

29. MR Tests – Soil Samples Cylindrical specimens, 2 in. f by 4 in. high
Undisturbed soil samples – Shelby tube (f = 2.8, 4 in.)

30. Typical MR Characterization
Greensboro, NC Airport
Subgrade Soils 28 M R = s d 2 = 24
A-4 soil at OMC
RESILIENT MODULUS M R
(ksi)
A-4 soil at OMC+3 20
Bilinear or
Arithmetic
Model 16 M = s
+ 1820 R d 2 12 R = 8 4 M = s R d M = s R d R 2 = R 2 = 2 4 6 8 10 12 14 16 18
APPLIED DEVIATOR STRESS s
(psi) d

31. Resilient Modulus Testing

32. Resilient Modulus Testing

33. Resilient Modulus Testing

34. Project Deliverables
Technical Notes have been / will be prepared and submitted to the OMP throughout the project duration to communicate specific findings and recommendations to OMP engineers
Several of the Project Tasks are being pursued simultaneously, and the specific delivery of results will be contingent upon availability of OMP data and other factors that depend on coordination with OMP
A Report summarizing the laboratory program will be prepared
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
Persistence length is the length which the polymer looks like straight.
-e : one negative charge

35. Illini Apparently Have Spent A Little Longer At No. 1 This Time!..GO
ILLINI !..