Asphalt Shingles in HMA Missouri DOT Experience

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Asphalt Shingles in HMAMissouri DOT Experience

• North Central HMA Conference
• Joe Schroer, PE
• January 10, 2007

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In The Beginning

• Approached by Pace Construction and Peerless
  Landfill
• MoDOT Not Using RAP in Mixtures
• Deleterious Material
• Stiffness of Asphalt in Shingles

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First LookThe Ex Factor

• Exhaustive Literature Search
• Exclusion of Tear Offs in States Allowing
  Manufacturing Waste
• Extra Clean Material Contained Little
  Deleterious Matter
• Exceptionally Stiff Asphalt Extracted from
  Shingles

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Shingle Components

• Asphalt ? 20-40
• Stiffen Roadway Asphalt
• Aggregate ? ?30
• Good Stuff
• Fiberglass or Paper Mat ? ?30
• No Harm if Well Dispersed

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MoDOT Goals

• Engineering Properties First
• Harmful Effects of Deleterious Material
• Asphalt Binder Properties
• Traffic Safety Nails, etc.
• If Everything Else Works Out, Landfilling is
  Reduced

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Why Should We Pursue Shingles?

• High Asphalt Content
• Granules Are Hard and Durable
• Recycling

COT
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Concerns

• How Will Deleterious Material Affect the Mixture
• Can the Low Temperature Grading be Maintained at
  Various Blending Ratios

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Asphalt After Blending with Shingle Asphalt

• Resist Rutting
• Resist Fatigue Cracking
• Resist Cold-Weather Cracking

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Asphalt Grades

• High Temperature for Rut Resistance
• Low Temperature for Fatigue and Cold Weather
  Performance
• Performance Graded PG
• PG 64-22 (PG Sixty-four Minus Twenty-two)
• High Temp 64C (147F)
• Low Temp 22C (-8F)

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High Temperature
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Low Temperature
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Assume Incomplete Blending
100
75
50
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Asphalt Modifications Require PG 64-22

• Stiffer at High Temperature OK
• Stiffer at Low Temperature
• Use Lower Percentage of Shingles
• Use Softer Roadway Asphalt

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Deleterious Evaluation

• Specification for Aggregate
• 0.5 Other Foreign Material
• Sticks, mud balls, deer fur, etc.
• Shingle OFM
• Approximately 3 Total

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Deleterious Material

• Nails
• Wood
• Plastic
• Cellophane
• Paper
• Fiber Board

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Trial by Fire
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No Difference

• Visually
• Standard Mixture Tests
• Placement

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Big Difference

• Rut Resistance
• Cold Temperature Tests
• OFM in Mixture

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Trial ProjectUS 61/67, St. Louis Co.

• Part of Study with Minnesota
• 4 Mixtures 19.0 mm Superpave
• PG 58-28
• 20 RAP
• 15 RAP, 5 Shingles
• PG 64-22
• 20 RAP
• 15 RAP, 5 Shingles

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Study Results

• IDT Testing by U of Mn
• Tensile Strength Little Difference
• Creep Stiffness Greatly Affected at Lower
  Temperatures
• Evaluation of Reflective Cracking in Sections to
  Be Made

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PG 64-22 PG 58-28
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Can Tear-Off Shingles be Used?

• Allowance in OFM Due to Small Percentage of
  Shingles and Trial Mixture
• Start with Softer Roadway Asphalt

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Where Are We?The Ex Factor 2

• Extrinsic Material Allowance Raised
• 3.0 Total
• 1.5 Wood
• Expect PG 64-22 met w/ PG 58-28
• Extra grades optional w/ testing
• Examining various proportions and asphalts
• Exuberant Contractors

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Cardboard
Milk Jugs, Aluminum
Cans
Plastic Bottles
Newspaper
Newspaper
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