Construction Quality Control Practices for Evaluation of InSitu Stiffness and Material Variability

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Construction Quality Control Practices for
Evaluation of In-Situ Stiffness and Material
Variability

• North Central Pavement Research Partnership
• University of Wisconsin Madison
• October 8, 2008
• John Siekmeier, PE

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Topics

• Testing for Compaction
• Changing from Density to Modulus
• New Field Testing Techniques
• Intelligent Compaction Equipment
• Data Management and Geostatistics
• What Weve Learned

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Testing for Compaction

• Uniformity is the Priority
• Traditional (Empirical Pavement Design, Soil
  Factor)
• Specify Relative Density (Proctor Test)
• Specify Moisture Limits (Proctor Test)
• Observation or Test Rolling
• Future (Mechanistic Pavement Design, MnPAVE)
• QC Intelligent Compaction Equipment
• QC/QA Continue to Specify Moisture
• QA Specify Modulus and Strength (LWD, DCP)

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Density Testing Issues

• Proctor had a Different Idea
• Optimum Moisture for Compaction
• Strength May Not be Achieved
• Rutting Due to Moisture and Construction Traffic

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Proctor Had a Different Idea 1933

• 12 inch firm blows
• not
• 12 inch free fall (drop)

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Proctor 1948

• This inadvertent substitution evidently led some
  organizations to assume that instead of striking
  a minimum length blow of 12 inches, the tamper
  should be dropped a distance of 12 inches in free
  fall.

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Proctor 1948

• Originally published objective of compaction in
  earth fills was a saturated penetration
  resistance of 300 lb per sq in.
• Soil would then have twice the penetration
• resistance required to permit loaded truck
  travel when fully saturated.

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• DENSITY
• 6.5 Increase
• STRENGTH
• 8.3 x Increase

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Changing from Density to Strength

• We Still Need Moisture Control
• Density
• Mass / Volume
• Proctor Test is NOT the Maximum
• Strength
• This is a Performance Related Parameter
• We Just Need Two of the Three
• Moisture and Strength

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Why Use Performance Based Tests?

• Achieve agreement between construction quality
  assurance, pavement design and performance.
• Quantify alternative materials and construction
  practices.
• Show economic benefit of improved materials.
• Reward good construction.
• This requires new specifications and new tools.
• Tools must be quantitative, portable, and
  accurate in the field.

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New Field Testing Equipment
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Light Weight Deflectometer (LWD)

• Impulse Device
• Load measured
• Velocity measured
• Deflection calculated
• Elastic modulus estimated
• Immediate results
• Trial Spec developed

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Buffers
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Load Cell
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Geophone
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Wireless Transmitter
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Intelligent Compaction Definition

• Intelligent compaction (IC) equipment measures
  and records the quality of compaction during the
  compaction process. The compactors force
  changes in real time to increase compaction where
  needed, while preventing over compaction. The
  equipment uses a global positioning system to
  create a map that shows the quality of compaction
  across the entire surface of each lift.

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Bomag Soil and Asphalt IC Systems
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Benefits to Mn/DOT

• Increased Compaction Uniformity
• Complete Documentation of Every Lift
• Automation and Better Record Keeping
• Improved Inspector Safety
• No More Sand Cone Testing

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QA During Bomag Dam Construction
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General QC/QA Procedure

• Quality Control by the Contractor includes
• Quality Control Plan
• Moisture testing
• Roller compaction value
• Corrective actions to be taken
• Quality Assurance by Owner includes
• Review and approval of the Contractors QC plan
• Analyses of the final recording pass of the IC
  roller
• QA testing using the light weight deflectometer
  (LWD) dynamic cone penetrometer (DCP) and
  moisture tests
• Review and approval of the Contractors QC report
• Archive of electronic QC and QA data

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IC Roller Specifications

• Provide real-time correction during compaction
• Provide current map for visual review on demand
• Provide paper maps for permanent documentation
• Provide an electronic data file in specified
  ASCII format
• Date, time, and location of the proof layer
• Roller compaction value (RCV) (modulus,
  stiffness, or another index)
• Resonance meter value (RMV) and roller pass
  number (RPN)
• Roller direction, speed, horsepower, and total
  mass
• Drum mass, width, diameter, frequency, amplitude,
  acceleration, force
• Position data and time stamp for each record
  accurate to the frequency of the drum

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Import Alignment from CAD
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Import Aerial Photography
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Import IC Roller Data
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Apply Quantitative Statistics to IC Data
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GIS Data Management System
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Characterizing Uniformity
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Worse (Short Range, High Sill)
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Semi-Variance
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Better (Short Range, Low Sill)
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Best (Long Range, Low Sill)
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30
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50
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Separation Distance (ft)
Relative Rating ONLY
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Research and Implementation Roadmap

• Mechanistic Empirical Design Framework 2000
• LWD Enhancement and Verification 2003
• Modulus of Select Granular 2004
• Moisture Effects on DCP and LWD 2006
• Modulus of Base Course w/ RAP (LRRB 812) 2006
• Validation of DCP/LWD Granular (LRRB 829) 2006
• Unsaturated Soil Pavement Design 2007
• Implementation of LWD and IC (FHWA) 2007
• MnPAVE for Local Roads (LRRB 828) 2007
• Compaction Specs for DCP/LWD (LRRB 860) 2008
• Best Value Granular for Road Foundations 2008

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Intelligent Compaction Projects

• 2004
• District 3, MnROAD
• 2005
• District 1, US 53, Duluth
• District 7, US 14, Janesville
• District 8, US 12, Atwater
• 2006
• District 2, TH 64, Bemidji
• District 3, MnROAD
• Metro District, I-494 Valley Creek Road, Saint
  Paul
• 2007
• District 3, US 10, Staples
• District 4, US 10, Detroit Lakes
• District 7, TH 60, Worthington
• Metro District, TH 36, Saint Paul
• 2008
• Kandiyohi County, CSAH 4
• Olmsted County, CSAH 2
• District 3, MnROAD

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Kandiyohi County, CSAH 4

• FHWA/TPF Research Project
• Accelerated Implementation of IC Technology for
  Embankment Subgrade Soils, Aggregate Base
  Asphalt
• June 15 17, 2008
• Site Details
• 3.2 miles
• 3 to 10 Compacted Subgrade
• 6 Class 5 Aggregate
• 4 HMA

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Subbase Layer Mapping Operation(Photo Courtesy
of Sakai)
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HMA Base Course Layer Compaction(Wearing Course
was also mapped)
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Aithon Software Output Passes
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Aithon Software Output CCV
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Aithon Software Output Temperature
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Premature Failure Base Course
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Olmsted County, CSAH 2

• LWD and Intelligent Compaction
• 0.8 miles
• 12 inches Select Granular
• 6-9 inches Aggregate Base
• 8 inches Concrete Surfacing

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AccuGrade Compaction
Radio
GPS Receiver
Display
Controller
Slope Sensor
Accelerometer
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Olmsted County, CSAH 2 CCV
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AccuGrade Compaction
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Olmsted County Zorn LWD

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LWD Target Values LRRB Inv 860
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Whats Next ?
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Whats Next in Minnesota

• Intelligent Compaction Specified in More
  Contracts
• Purchase Specialized IC Validation Test Equipment
• Industry/Agency Inspector Training Workshop
• Educate Designers, Opportunity to Refine/Validate
  Design
• Eliminate Control Strips
• Specification Includes Design-Based Minimum
  Targets
• Specification Includes Design-Based Uniformity
  Targets
• Continued Participation with National Projects
• NCHRP 21-09 Intelligent Compaction Specifications
• FHWA-led Intelligent Compaction Pooled Fund

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Conclusions

• Construction equipment and field tests are now
  available that can measure the mechanistic
  properties used to design pavements and predict
  performance.
• IC rollers are well made and easy to operate.
• Operators learn how to make better decisions.
• Problem areas are identified early and corrected.
• IC rollers can measure the stiffness of the
  ground and produce surface covering
  documentation.
• Data transfer was functional, but must be
  improved.

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Acknowledgements

• Special thanks to the following organizations
• Ammann, Bomag, Caterpillar, and Sakai
• CNA Consulting Engineers
• Colorado School of Mines
• Federal Highway Administration
• Iowa State University
• Loughborough University
• Minnesota Department of Transportation
• Minnesota Local Road Research Board
• University of Illinois
• University of Minnesota
• University of Wisconsin

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Thank You.

• Questions?
• www.dot.state.mn.us/materials/researchic.html