Rapid Soil Stabilization Technologies (TPD0811007)

 

Photo: Soil Improvement (with Heavy Equipment)

 

Photo: Aircraft Parking

 

Photo: Matting Systems

 

Photo: ERDC HVS Test Facility, C-130 Wheel, 30,000 Lbs on 6” of Stabilized Soil

 

Photo: Dust Control Application

 

APPROACH

 

• Applied Research (6.2) – Development of promising technologies for soil stabilization
  • Polymer/Cement blends
  • Fiber/Cement blends
    • Synthetic
    • Wood/cellulose
  • Polyurethanes/Epoxies
    • Single and two-component mixtures
  • Cold-weather curing of cements
• Demonstration Technology (6.3) – Utilize existing technology for military applications
  • Scale-up of polymer/cement and fiber/cement stabilization from laboratory to field
  • Testing of commercial mat systems for airfield applications

 

Products

 

• Airfield Matting
  • Materials
  • Construction and design methodology
• Dust Control
  • Materials
  • Application and Construction Methods
• Soil Stabilization
  • Materials – Including Freeze-thaw areas
  • Aircraft Specific Thickness Design
  • Construction Methods

 

 

Photo: Dust Control Application

 

Photo: ERDC HVS Test Facility, c-130 Wheel, 30,000 Lbs on 6” of Stabilized Soil

Rapid Stabilization Work Unit Plan

 

Table: Rapid Stabilization Work Unit Plan

 

Pertinent Work Units

 

• C-17 Shear-Resistant Stabilizer Development – FY07 End
• Dust Control Technologies – FY07 End
• Stabilization of Thawing Soils – FY05 End
• Rapid MOG Enhancement Technologies – Need Extension through FY06
• Demonstration of Advanced Stabilizer Technologies (C-130) – FY05 End
• Field Testing of Advanced Stabilizer Technology (C-17) – FY06 End
• Evaluation of Structural Requirements for Stabilized Airfields – FY06 End
• Maintenance and Repair of Stabilized Layers – FY06 End
• Demonstration of C-17 Stabilization Technology – FY06 New Start

 

Accomplishments Thru FY04

 

• Progress:
  • Tested Commercial Mat Types Over Different Soil Strengths
    • C-130 contingency weights
  • Rapid Soil Stabilizers
    • Fibers and fast-setting cements
    • Polymers and fast-setting cements
  • Improved Dust Abatement
    • Best construction techniques
    • Best application equipment
    • Evaluated commercial products
  • Developed Cold Weather Stabilizers
    • Admixtures in cement for curing under freeze-thaw conditions
  • Ft. Bragg Demo

 

Photo: Airfield Matting

 

Photo: Soil Stabilization

 

Photo: HUMVEE Sprayer

Ft. Bragg Demo – Mat testing for C-130 Loads

Test

Mat

6” Clay-Gravel Base (40-50 CBR)

Pressure Cell

Buckshot Clay 24” Subgrade (8-10 CBR)

Test

Mat

6” Base

Pressure Cell

Buckshot Clay 24” Subgrade (8-10 CBR)

Test

Mat

6” Base (3-5 CBR)

Pressure Cell

Buckshot Clay 12” Subgrade (8-10 CBR)

 

Photo: 6” Clay Gravel Base

 

Photo: Installing Pressure Cells at Top of Clay Subgrade

 

Photo: C-130 Load Cart on Durabase

Ft. Bragg Demonstration – Materials

 

• ACE Mat
  • Lightweight, easy to handle
  • Easy to install
  • Fiberglass
• Polymers and Fibers – Why?
  • Reduced Logistics
    • Polymers and fibers weigh less than half of cement
  • Improved Performance
    • Less cracking means less FOD
• Polymer/Cement Synergy
  • Polymer/fiber helps cement
  • Cement Helps polymer/fiber

 

Table: Fort Bragg Soil Strengths

 

Photo: Fibers

 

Photo: Polymer

C-130 Load Testing of Stabilized Surfaces

 

Photo: ERDC HVS Test Facility

 

Graph: Rut Depth with Number of C-130 Wheel Passes

Ft. Bragg Demo Candidates – Testing

 

• C-130 Wheel load 30,000 lb, 750 passes
• One Day Cure
• SM Soil

 

Photo: Loaded C-130 Wheel on SM Soil

<Cracked at edge of wheel path, 5” rut>

 

Photo: C-130 Testing on Emulsion Polymer/Cement

<Cracked at edge of wheel path, 3” rut>

 

Photo: C-130 Testing on Fiber/Cement

<1/2” rut @ 750 passes>

Ft. Bragg Demo – C-130 Parking Aprons

 

• Two C-130 Parking Aprons – 40,000 sq. ft. each
  • Apron 1
    • Half ACE mat
    • Half polymer/cement
  • Apron 2
    • Fiber/Cement

 

• Sicily ALZ, Ft. Bragg, NC

Photo: Apron 1 – ACE Mat/Polymer/Cement

 

Photo: Apron 2 – Fiber/Cement

FY05 Activities

 

• C-17 Load Testing – Contingency loads at 206 kips/gear
  • Commercial Mats
    • Soloco Durabase – Heavy Duty
    • Soloco Bravo – Lightweight
    • ACE mat – Lightweight
  • Stabilized Soil
    • Fiber/Cement
    • Synthetic
    • Wood/Cellulose ?
• Laboratory Testing
  • Moisture-Cure Polyurethanes
  • Different fiber types
    • Monofilament vs. fibrillated
    • Wood/cellulose
  • Improve fiber/soil/cement adhesion

 

Photo: Test Facility

 

Graph: Stress vs. Strain

MATS

 

• What have we learned so far?
  • Durabase is an excellent load-bearing mat
    • Logistically unwieldy
    • Heat resistance?
  • Bravo mat suffered mechanical failure
  • ACE Mat is an excellent lightweight mat for medium strength (CBR >8) soils
    • 1000 passes of C-17 at contingency operating weight (206 kips) with minimal damage over CBR 8-10 SM soil
    • Needs proper anchoring for wind loads

 

Photos: Various Mats

 

Soil Stabilization

 

• Laboratory Testing of Soil Stabilizers
  • Moisture-Cure Polyurethanes
  • Different fiber types
    • Monofilament vs. fibrillated
    • Wood/cellulose
  • Improve fiber/soil/cement adhesion

 

Photos: Laboratory Testing of Fiber Types

 

Graphs: Stress vs. Strain

Moisture Cure Polyurethanes – MCPUR

 

Graph: Unconfined Compressive Stress vs. MCPUR, 1% Soil Moisture

 

Graph: Unconfined Compressive Stress vs. MCPUR, 5% Soil Moisture

Moisture Cure Polyurethanes – MCPUR

 

Graph: Toughness vs. MCPUR, 1% Soil Moisture

 

Graph: Toughness vs. MCPUR, 5% Soil Moisture

MCPUR Cure Time – UCS

Graph: Unconfined Compressive Stress vs. Cure Time (Days) 

MCPUR Cure Time – TOUGHNESS

Graph: Toughness vs. Cure Time (Days)

So Why not MCPUR?

• Advantages
  • Super stress and strain properties
  • Would be great with added fibers
• Disadvantages
  • Hard to construct with
  • Viscosity like honey
  • Sticks to equipment
  • Difficult to clean
  • Very expensive
  • Poor shelf life
  • Hazardous

Photos: Application Equipment

 

Photo: Aircraft/Airfield 

Effects of Cement and Fibers on Soil

• Stress/Strain Response – ¾” Fibers

Graph: Stress/Strain Response, Load Lbs. vs. In.

Effects of Fiber Type and Concentration

Graph: Unconfined Compressive Stress vs. Stabilizer Type

 

Graph: Toughness vs. Stabilizer Type

 

Soil Stabilization

• What have we learned so far?
  • Cement is hard to beat – Economical, ubiquitous, easy to use
    • FOD nightmare when it fails
  • Fibers are excellent in blends with binders such as polymers and cements
    • Fibers reduce cracking – less FOD
    • Too long and fibers are hard to construct with
  • Emulsion polymers are easy to use
    • Great for weatherproofing, dustproofing surfaces
    • Don’t perform as well as fibers in blends with cement
    • Slow to cure without ‘help’ (cement)
  • Fibers
    • Improving adhesion of fiber to cement/soil is beneficial- ongoing research
  • Curing Polymers – Epoxies/polyurethanes
    • Single Component Moisture Cure Polyurethanes (MCPUR)
    • Great Properties
    • Hard to control, construct with
    • Two-Component Polyurethanes/Epoxies
    • Great Properties
    • Strict mixing requirements – special equipment needed
    • Can be controlled better than MCPUR

FY06-07 Activities

• FY06 – C-17 Loads
  • Field Studies
    • Soil Stabilization
    • SM Soil 6” Depth, CBR 8-10
      • Synthetic Fiber/Cement Blends
      • Wood/Cellulose/Cement Blends
    • Clay Soil
      • Candidate materials will be based on laboratory studies
    • Maintenance and repair will be accomplished during field studies
    • Mat testing over Clays
  • Laboratory Studies
    • Stabilization of Clay Soil
    • Cement, lime, fibers, ionic stabilizers
• FY07 – C-17 Demonstration