BCRA Poster

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Subgrade Soil Support and Stabilization
OHARE Airport Modernization Research Project
Research Progress and Future Tasks Sept. 21,
2006
Co-PIs Erol Tutumluer
Marshall R. Thompson RA
Deb Mishra
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Introduction

• The strength and performance of an airport
  pavement related to the structural design and the
  subgrade soil characteristics

• This project provides testing and analysis to
  establish subgrade support and stabilization
  requirements for OHare airport pavements

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Research Objectives

• Consider/Establish subgrade support and
  stabilization requirements with respect to
• Need for subgrade stabilization
• Selection of lime and other suitable admixture
  stabilization considerations
• Stabilization depth
• Estimate subgrade support for various
  combinations of subgrade stabilization treatments
  and prepared subgrade conditions

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Progress Made In 2005-06

• A project research paper was presented at the
  2006 ASCE Airfield and Highway Pavement Specialty
  Conference, Atlanta, GA, April 30 May 3, 2006
• Published in the Proceedings book Airfield and
  Highway Pavements, edited by I.L. Al-Qadi
• Characterizing Subgrade Soils and Establishing
  Treatment Needs for a New Runway at the Chicagos
  OHare Airport
• by H.S. Brar, E. Tutumluer, M.R. Thompson,
  L. Gosain, and R. Anderson

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Progress Made In 2005-06

• On April 5th, 2006, the Co-PIs joined a TEL-CON
  meeting with the OMP concerning the project
  findings on subgrade stabilization and additional
  frost action effects. It was recommended that Dr.
  Dempsey (a participant in the TEL-CON) conduct a
  climatic-modelling study of the 9-27 RW.
• Both North Runway 9L-27R and South Airfield
  subgrade soil support and stabilization needs
  were discussed
• effectiveness of lime stabilization on primarily
  silty soils with low clay contents (less than
  20),
• adequate strength gain requirements,
• poor workmanship and inadequate construction
  quality control,
• construction cut off dates for lime treatment
  effectiveness,
• frost penetration effects, and
• Cement treatment as an option to include in the
  construction specifications (and use in certain
  project locations in case lime treatment becomes
  unsatisfactory for the primarily silty, low clay
  contents soils to be encountered during subgrade
  preparation)

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Progress Made In 2005-06

• Marshall Thompson traveled to the OMP office on
  April 11th and participated in a conference at
  ORD with OMP staff concerning soil stabilization
  (lime/cement, frost action effects, and use of
  fly ash as a stabilization admixture)
• Erol Tutumluer gave a progress update on July
  20th at the OMP office and found out that fly ash
  was now used for modification of the North Runway
  soils
• Marshall Thompson traveled to the OMP office on
  July 28 and participated in a conference with OMP
  staff and 9-27 Design Staff concerning
  treatment options for unstable subgrades. He
  participated in the subsequent development of
  recommendations.

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Progress Made In 2005-06

• Professor Barry Dempsey, a UIUC expert on
  climatic effects has completed a study of frost
  penetration and freeze-thaw cycle activity for
  the various 9-27 pavement configurations. The
  study considered ORD climatic data for the period
  1996 2006. The report has been published as
  CEAT TN 26.

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TECHNICAL NOTES

• Technical Notes have been prepared and submitted
  to the OMP throughout the project duration to
• Establish the Best Demonstrated Available
  Technology (BDAT) for subgrade soil evaluation
  and stabilization
• 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)
• TN13 Moisture Limitations for Lime
  Stabilization
• TN14 Admixture Stabilization (Lime Treatment of
  Subgrades)
• TN19 Progress Report on Laboratory Soil Test
  Results
• 
  (March 2006)

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DEMPSEY STUDY FINDINGS
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TOTAL PVT THICKNESS 40 INCHES
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9-27 PAVEMENT
FROST LINE 46 INCHES
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DATE FROST DEPTH (INCHES) DATE FROST DEPTH (INCHES)
2-97 46 1-02 30
1-98 28 2-03 40
1-99 43 2-04 46
2-00 37 1-05 36
1-01 47 12-05 36
AVERAGE 39 INS
9-27 PAVEMENT SECTION
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FY 07 Year 3 Project Tasks
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FY 07 Year 3 Project Tasks

• Task 1
• Cooperate with OMP in the reviewing (and
  modifying if appropriate) Section P-152
  (Excavation and Embankment) and Section P-159
  (Lime Modified Soils) or Fly Ash Modified Soil
  Specs?
• Experiences (problems/successes) from the current
  9-27 contract should be considered
• The modified versions should be included in
  future contracts

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FY 07 Year 3 Project Tasks

• Task 2
• Cooperate with OMP in the reviewing and
  modifying Section P-158 (Lime Stabilized
  Subgrade) for inclusion in the upcoming paving
  contract
• Current version cites latest edition of IDOT
  Specs. Should reference the IDOT 2002 version
• Modify Spec. (as needed) to include cement as a
  possible admixture
• Incorporate frost action and freeze-thaw
  potentials from Dempseys study (TN 26) as
  guidelines
• Will construction be permitted outside the
  current April 15 Sept 15 window?
• Other issues??

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FY 07 Year 3 Project Tasks

• Task 3
• Evaluate the 9L-27R runway/taxiway soil lime
  stabilization and (fly ash) modification for
  meeting the subgrade support (k-value)
  requirements
• The research team will support the activities of
  OMP in
• Characterizing soils _at_ finish grade
  elevation for stabilization admixture
  selection.
• Evaluating completed modification/stabiliz
  ation effort.
• Field Validation of completed pavement
  structure.

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FY 07 Year 3 Project Tasks

• Task 4
• Evaluate currently available geotechnical/subgrad
  e data for the South Airfield of the OHare
  Airport with particular emphasis on the
  stockpiled soils
• Summarize technology and experiences from North
  Runway (9-27) and apply to the South Airfield
• Advise on the soil sampling needs and if
  considered essential, develop recommendations for
  additional soil exploration/sampling activities
• Develop/conduct a laboratory testing program for
  soil treatment and subgrade support for the South
  Airfield

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Project Schedule Deliverables

• Technical Notes will be prepared and submitted to
  the OMP throughout the duration of this project
  to communicate specific findings and
  recommendations to OMP engineers as needed
• Several of the Project Tasks are already 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
• Continue to work with OMP on current and future
  subgrade soil support and stabilization needs for
  all OHare runways/taxiways. This will be in the
  form of sustained support for working with OMP on
  subgrade soil support issues

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Any Questions?
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