Got Density?

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Got Density?
Asphalt Pavement Assn. of Indiana Winter
Conference December 2010
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Why measure density?

• Surrogate for other properties
• Strength
• Durability
• Permeability
• Easy and fast

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Rutting vs. Air Voids
Ref WesTrack
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Rutting vs. Air Voids
1/2 Rutting in One Year
Ref Mn/ROAD
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Fatigue vs. Air Voids
Ref WesTrack
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Permeability
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Permeability
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Retained Penetration vs Air Voids
Ref NCAT Text Book
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Pavement Life vs. Air Voids
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Getting Density

• Lift Thickness
• Temperature
• Compaction Support
• Equipment

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NCHRP Report 531

• Relationships of HMA In-Place Air Voids, Lift
  Thickness, and Permeability (NCHRP 9- 27)
• Recommended minimum lift thicknesses
• 3 X NMAS for fine-graded mixes
• 4 X NMAS for coarse-graded mixes
• Thin lifts cool faster
• less time available for compaction

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MultiCool

• FREE Software for Computing Compaction Window
• Base Temp
• Weather Conditions
• Lift Thickness
• Mix Temp
• Latitude
• Available at www.hotmix.org

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MultiCool
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Temperature
80OF Surface Air Temperature, 5 mph wind
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Temperature
50OF Surface Air Temperature, 5 mph wind
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Temperature
30OF Surface, 40OF Air Temperature, 15 mph wind
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Compaction Support
Weak Support Leads to Poor Compaction!
Weak!!!
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Compaction Support
Strong Support Helps Compaction!
Strong!!!
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Balancing Production

• Balance of plant production, trucking, paver
  speed and rollers
• Slow and steady wins the race
• Speeding up to get rid of trucks not recommended.
• Hurts ride
• Non-uniform compaction

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Joint Density

• Controlling segregation important
• Proper joint construction important
• Sealers
• Echelon paving
• Joint density
  specification

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Longitudinal Butt Joint
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Notched Wedge Joint
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Notched Wedge Joint Attachment
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Joint Rolling - Unconfined Edge
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Longitudinal Joint
Hot Mat
Cold Mat
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Longitudinal Joint
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Longitudinal Joint
Unrolled
Rolled
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Minimizing Joint Problems

• Minimize Joints
• Pave in Tandem!
• May Require
  More Lane
  Closures
• But, It Minimizes
  Return Trips!

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Final Quiz
Q - What is the maximum number of rollers needed
on a paving project?
A - Whatever it takes to get density.
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1
4
2
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The Future is Bright!

• Better Tools to Help Us!
• Oscillatory Compaction
• Intelligent Compaction
• GPS Location
• Mat Stiffness

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Dont Forget Quality

• Diamond Achievement Commendation
• Diamond Quality Commendation
• Diamond Paving Commendation