Asphalt Shingles in HMAMissouri DOT Experience

North Central HMA Conference

Joe Schroer, PE

January 10, 2007

In The Beginning

• Approached by Pace Construction and Peerless Landfill

–MoDOT Not Using RAP in Mixtures

–Deleterious Material

–Stiffness of Asphalt in Shingles

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

Shingle Components

• Asphalt 20%-40%

–Stiffen Roadway Asphalt

• Aggregate 30%

–Good Stuff

• Fiberglass or Paper Mat 30%

–No Harm if Well Dispersed

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

Why Should We Pursue Shingles?

• High Asphalt Content

• Granules Are Hard and Durable

• Recycling CO$T

Concerns

• How Will Deleterious Material Affect the Mixture

• Can the Low Temperature Grading be Maintained at Various Blending Ratios

Asphalt After Blending with Shingle Asphalt

• Resist Rutting

• Resist Fatigue Cracking

• Resist Cold-Weather Cracking

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 64°C (147°F)

Low Temp –22°C (-8°F)

High TemperatureCritical High Temp.

50

60

70

80

90

100

110

120

130

140

150

100 80 60 40 20 0

Percent Virgin Binder

° C

0 4 8 12 16 20

Percent Shingles @ 5% Total Binder in Mix

58-22

52-28

58-28

58-28 Flux

64

70

76

Low TemperatureCritical Low Temp.

-40

-30

-20

-10

0

10

20

30

40

50

100 80 60 40 20 0

Percent Virgin Binder

° C

0 4 8 12 16 20

Percent Shingles @ 5% Total Binder in Mix

58-22

52-28

58-28

58-28 Flux

-16

-22

-28

Assume Incomplete BlendingCritical Low Temp.

-40

-30

-20

-10

0

10

20

30

40

50

100 80 60 40 20 0

Percent Virgin Binder

° C

0 4 8 12 16 20

Percent Shingles @ 5% Total Binder in Mix

58-22

52-28

58-28

58-28 Flux

-16

-22

-28

50%

75%

100%

Asphalt Modifications Require PG 64-22

• Stiffer at High Temperature – OK

• Stiffer at Low Temperature

–Use Lower Percentage of Shingles

–Use Softer Roadway Asphalt

Deleterious Evaluation

• Specification for Aggregate

–0.5% “Other Foreign Material”

• Sticks, mud balls, deer fur, etc.

• Shingle “OFM”

–Approximately 3% Total

Deleterious Material

• Nails

• Wood

• Plastic

• Cellophane

• Paper

• Fiber Board

Trial by Fire

No Difference

• Visually

• Standard Mixture Tests

• Placement

Big Difference

• Rut Resistance

• Cold Temperature Tests

• OFM in Mixture

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

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

10.8 12.0

19.5

9.5

34.4 34.7

0

10

20

30

40

-10C -20C -30C

Stif

fnes

s @

100

sec

20% RAPPG 64-22

15% RAP5% shing.PG 64-22

6.1

11.5

17.3

8.1

16.6

21.4

0

10

20

30

-10C -20C -30C

Stif

fnes

s @

100

sec

20% RAPPG 58-28

15% RAP5% shing.PG 58-28

4.54.9

3.94.3 4.2

4.7

0

3

6

-10C -20C -30C

Ten

sile

Str

engt

h [M

Pa]

20% RAPPG 64-22

15% RAP5% shing.PG 64-22

4.1

4.5 4.44.4 4.54.5

0

3

6

-10C -20C -30C

Ten

sile

Str

engt

h [M

Pa]

20% RAPPG 58-28

15% RAP5% shing.PG 58-28

PG 64-22 PG 58-28

Can Tear-Off Shingles be Used?

• Allowance in OFM Due to Small Percentage of Shingles and Trial Mixture

• Start with Softer Roadway Asphalt

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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Plastic Bottles

Milk Jugs, Aluminum

Cardboard

Cans

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