February 26, 2015 David P. Shiells, P.E. District Materials - - PowerPoint PPT Presentation

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February 26, 2015 David P. Shiells, P.E. District Materials - - PowerPoint PPT Presentation

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Uniform Paving Platform Regional Asphalt Seminar, Fredericksburg, VA February 26, 2015 David P. Shiells, P.E. District Materials Engineer Why Do we Need a Uniform Paving Surface ? Rideability Smooth base = smooth surface (usually)

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Uniform Paving Platform Regional Asphalt Seminar, Fredericksburg, VA

February 26, 2015

David P. Shiells, P.E. District Materials Engineer

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Why Do we Need a Uniform Paving Surface ?

Rideability

  • Smooth base = smooth surface (usually)
  • Uneven base = rough surface (always)
  • Smooth pavements last longer and are safer for motorists

Density of Surface Mix

  • Uneven support will result in uneven density
  • Density is important for longevity of pavements
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Life is Not Perfect…

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Construction is Not Perfect Either…

Good

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Construction is Not Perfect Either…

Good Not so good

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Variable Width of Base….

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A Little Bit of Scabbing…

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Variable Base Thickness…

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Deterioration of Milled Surfaces…

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What is the Solution ?

Mill Deeper

  • Contracts typically require 1.5” to 2” of milling
  • Make a second pass of the milling machine
  • Add a second layer of SM or IM mix

Patching

  • Type I - <20 sf, < 5” deep
  • Type II - >20 sf, <5” deep
  • Type III - >5” deep

Scratch/Leveling Course

  • Localized application of surface mix
  • Level depressions, scabbing or distorted areas
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Special Provision for Asphalt Concrete Scratch/Leveling Course Prior to Plant Mix Overlay

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SP for Scratch/Leveling Course

General

  • Localized application of surface mix
  • Level depressions, scabbing or distorted areas
  • The Engineer must authorize scratch/level prior to use

Definitions

  • Type I - <50% of area to be paved
  • Type II - > 50% of area to be paved

Materials

  • Same as surface mix specified
  • SM-4.75, SM-9.0, SM-9.5, etc.
  • Not for SMA !

Measurement/Payment

  • Type I - 2 x contract price for surface mix
  • Type II - 1.5 x contract price for surface mix
  • OR pay by the ton when specified as a bid item
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It Is Not There Yet !

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It Is Not There Yet !

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What Would You Do ?

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What Would You Do ?

  • A. Mill Deeper
  • B. Patch
  • C. Scratch/Level
  • D. Do Nothing
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What Would You Do ?

  • B. Patch
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What Would You Do ?

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What Would You Do ?

  • A. Mill Deeper
  • B. Patch
  • C. Scratch/Level
  • D. Do Nothing
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What Would You Do ?

  • A. Mill Deeper
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What Would You Do ?

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What Would You Do ?

  • A. Mill Deeper
  • B. Patch
  • C. Scratch/Level
  • D. Do Nothing
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What Would You Do ?

  • D. Do Nothing
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Conclusions

Uniform Paving Surface

  • Promotes smoother pavements
  • Helps with achieving uniform density

Condition of Milled Surfaces

  • Very difficult to predict during contract preparation
  • Can change with time, weather conditions and traffic
  • Old pavements are prone to stripping
  • Scabbing is a common problem

Tools to Achieve Uniform Paving Surfaces

  • Deeper milling
  • Patching
  • Scratch/level
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And now, the contractor’s perspective…